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With the advent of cyber-physical system-based automation and intelligence, the development of flexible and wearable devices has dramatically enhanced. Evidently, this has led to the thrust to realize standalone and sufficiently-self-powered miniaturized devices for a variety of sensing and monitoring applications. To this end, a range of aspects needs to be carefully and synergistically optimized. These include the choice of material, micro-reservoir to suitably place the analytes, integrable electrodes, detection mechanism, microprocessor/microcontroller architecture, signal-processing, software, etc. In this context, several researchers are working toward developing novel flexible devices having a micro-reservoir, both in flow-through and stationary phases, integrated with graphanized zones created by simple benchtop lasers. Various substrates, like different kinds of cloths, papers, and polymers, have been harnessed to develop laser-ablated graphene regions along with a micro-reservoir to aptly place various analytes to be sensed/monitored. Likewise, similar substrates have been utilized for energy harvesting by fuel cell or solar routes and supercapacitor-based energy storage. Overall, realization of a prototype is envisioned by integrating various sub-systems, including sensory, energy harvesting, energy storage, and IoT sub-systems, on a single mini-platform. In this work, the diversified work toward developing such prototypes will be showcased and current and future commercialization potential will be projected. [ABSTRACT FROM AUTHOR]

Herein, a novel microfluidic-biochip enabled with surface enhanced Raman spectroscopy (SERS) as a readout has been demonstrated for uric acid (UA) detection as point-of care (POC) device. Three different biochip designs (D1, D2 and D3) containing pillars in a microchannel with different bending ratios were conceived and optimized for various mixing parameters using a multiphysics simulation tool. The microchannel, integrated with pillars, provide pressure perturbation, sharp corners, and variation in bending ratio improves phase shift and mixing index. Subsequently the microfluidic-biochips were fabricated by a combination of photo-and soft-lithography, and bonding strength between two Polydimethylsiloxane substrates were found stable up to a flow rate of 1.8 ml minâˆ'1. Further to realize SERS activity in the microfluidic-biochip, cubic shape silver nanoparticles (AgNPs), with an average size ∼68 nm, were synthesized using poly-ol method. The SERS activity was optimized by simultaneously flowing AgNPs and crystal violet (CV) dye of 10âˆ'6M, with double inlet in the reservoir and highest sensitivity was achieved in the D3 biochip. Further, D3 biochip was employed for detection of extended concentrations of CV and UA. The enhancement factor limit of detection and relative standard deviation was found to be 2 Ă— 107, 8.9 Ă— 10âˆ'11 and 2.7% respectively for CV and 3.1 Ă— 103, 3.2 Ă— 10âˆ'7 and 2.9% respectively for UA. Interference of UA with lactic acid has been tested and device was able to detect signature peaks of both biomarkers up to 50 Ă— 10âˆ'9 M concentration. Thus, the developed microfluidic-biochip device has potential to be used in a POC setting for onsite detection of biomarkers. [ABSTRACT FROM AUTHOR]

Realization of laser-induced graphene (LIG) by ablating laser on several substrates, like polyamide (PI), has gained huge attention. Generally, a CO2 laser, with a 10.6- $\mu \text{m}$ wavelength, has been reported to form LIG. However, higher build area, the requirement of a higher power, limited LIG conductivity values, infrared wavelength, and cost are several drawbacks of the CO2 laser-based process. Herein, a 3-D printer, loaded with a low-power (2.8 W) blue (450 nm) laser diode, has been demonstrated to create such LIGs with higher conductivity on PI sheets. The LIGs, with varying conductivity values, have been fabricated by diversified laser parameters achieving maximum conductivity of 2572.19 S/m, which was more than seven times higher than the one achieved by a CO2 laser. Subsequently, such LIG was transferred to a lamination sheet, named T-LIG, using a laminator. Finally, T-LIG based microfluidic device was developed with a microchannel and three integrated electrodes for electrochemical detection of folic acid, achieving a limit of detection of $10 ~\mu \text{M}$. Similarly, a microfluidic fuel cell was developed using T-LIG which provided a maximum power density of $5.06 ~\mu \text{W}$ / cm2 with a maximum open-circuit voltage of 50 mV. Overall, such T-LIG-based microfluidic devices have huge potential for diverse applications. [ABSTRACT FROM AUTHOR]

3D printing offers a novel, time-efficient, and multi-material fabrication platform for numerous applications owing to its potential to rapidly manufacture low-cost and 3D printed (3DP) structures. In this paper, polylactic acid (PLA) and conductive composite graphene/PLA filaments were used to fabricate 3DP microchannels and electrodes intended for enzymatic biofuel cells (EBFCs) using a commercial bench-top 3D printer. This 3D printing technology delivers a simplistic, cost-effective, and quick fabrication process, which eliminates the requirement of any further amendment and post-processing. With this technology, we demonstrate structurally simple, miniature 3DP microfluidic membraneless EBFCs (3DP-MM-EBFCs), served with glucose and oxygen with the utilization of redox mediators generating continuous power. The cell performance was evaluated at different flow rates, obtaining open circuit potential (OCP) 0.425 V and maximum peak power density (PD) $4.15~\mu \text{W}$ /cm2 at a current density (CD) of $13.36~\mu \text{A}$ /cm2. The advancement in 3DP electrode surface characteristic and the dimethylformamide (DMF) treatment is carried onto the electrode surface followed by the immobilization of the enzymes individually. The 3DP fabrication technology demonstrated the feasibility of simple and advanced microfabrication techniques to build a well-organized plug-and-play and rapidly analyzed device to power several portable low-power devices. [ABSTRACT FROM AUTHOR]

Recent progress in the in situ synthesise of various nanomaterials has gained tremendous interest and wide applications in various fields. For the first time to the best of our knowledge, this work reports a methodology of ultra-fast in situ synthesis of cobalt–cobalt oxide-reduced graphene oxide (Co−Co3O4−rGO (CC–rGO)) composite by laser ablation. The photothermal reduction technique was leveraged to develop the CC–rGO. For this, a low-cost 450 nm blue diode laser was irradiated onto a grade 1 filter paper in the presence of cobalt ions readily patterns the carbon matrix of paper to the composite material. Moreover, the variation of cobalt concentrations from 0.1–0.5 M led to structural and morphological changes. Standard techniques were adopted for thorough characterizations of developed sensor material for conductivity analysis, specific surface area, crystal-structural information, surface morphology, and chemical composition. The observed results were highly promoting towards the electrochemical sensing applications. Further, the developed sensor was found to be highly selective toward detecting a vital bio analyte alkaline phosphatase (ALP). The sensors performance was highly significant in the linear range of 10–800 mU l−1 with a detection limit of 10.13 mU l−1. The sensors applicability was further validated in actual human serum samples via a recovery-based approach. In the future, the developed in situ material methodology can begin a rapid composite material synthesis at a larger scale. [ABSTRACT FROM AUTHOR]

There has been expeditious growth and advancement in the development of portable, automated, integrated, and miniaturized temperature management systems. Temperature management system plays a vital role in microfluidic technology, an emerging area that couples multidisciplinary fields and manipulates small amounts of fluids (10−9–10−18 L). A microthermofluidic (MTF) system is designed by combining microfluidics and a thermal management system. The MTF approach harnesses the fluid mechanism to coordinate, manipulate, and merge the reaction sample and provide an effective and efficient desired temperature that plays significant progress in several biochemical, biomedical, and biological applications. This system can accomplish numerous purposes by either varying the reaction conditions within a microchannel or performing reactions in series, parallel, or combinations. Further, these reactions usually require a precise, consistent, and stable temperature, which can be achieved using contact or non-contact heating methods such as electrical, optical, acoustic, and mechanical heating. This work describes thermal energy sources in microfluidic devices and highlights advancements in microthermofluidic devices used for nanoparticle synthesis, biochemical, biomedical, and engineering applications. This work comprehends the general review on recent advances combining microfluidics and thermal management systems. Finally, challenges involved in the extensive use of MTF devices are discussed, and further deliberations for future research in this area are highlighted. The wide range of applications necessitates rapid thermal regulation with significant progressive hints for the biomedical, biotechnological, and chemical sub-areas, relying on the appropriate heating method. [Display omitted] [ABSTRACT FROM AUTHOR]

As the fossil fuels are depleting with time, the research work in the biofuels domain is rapidly growing. The blends of biofuel can be used as automobile fuel and the existing methods to detect the blending ratio have heavy one-time test cost, need controlled environment and require experienced operators. It is well observed that fuel mixture affects lubricating properties of the fuel and thereby the engine performance. As lubricating properties are related to physical properties, developing a sensor, based on this, can provide a reliable and effective solution to detect and monitor fuel blending. This work describes the computational and the comparative experimental analysis of a microfluidic-device which performs blending studies by analyzing the interface position of the fluid occupancy in a micro-channel and its variations. The device was fabricated in acrylic using a well-established micro-fabrication technique, and is re-usable, re-calibrated and can be integrated with the existing microcontrollers of automobiles. The viscosity of the various bio-diesel blends can be used to indicate the fraction of bio-diesel in the fuel sample based on the best fit curve of the percentage of channel fraction occupied by the samples. The interface shift is because of the greater occupancy rate of a higher viscous sample in the channel. The best fit curve was determined based on an extensive testing of various oils including the hair oils, machine oils etc. of different densities to confirm the interface shifting phenomenon. [ABSTRACT FROM AUTHOR]

Microfluidic microbial fuel cells (μ-MFCs) have received considerable attention due to their ability to generate green and qualitative self-sustainable energy. Several electrodes and device fabrication methodologies, and various electrochemically active bacteria (EABs), along with their effect on MFC performance with various operating parameters, have been well reported. However, shorter life, lower throughput, and high operating and maintenance overheads are major impediments to their development towards commercialization. In this context, simple and cost-effective bioelectrodes using printed circuit board (PCB) and a polymer based microchannel have been fabricated using modern photolithography and soft-lithography techniques respectively. Furthermore, the etched PCB electrodes were patterned with multi-walled carbon nanotubes (MWCNT). Subsequently, these bioelectrodes were assembled over a Y-shaped microchannel and tested under a co-laminar microfluidic flow environment powered by Shewanella putrefaciens. Various volumetric bacterial experiments and flow rate studies have also been conducted to find the most appropriate optimum bacterial volume and power efficiency. Subsequently, extensive potentiometric electrochemical studies, such as Open Circuit Potential (OCP) and polarization analysis, were accomplished using electrochemical workstation. This well-developed handheld μ-MFCs yields a maximum open circuit potential 395 mV with maximum power density of 239.2 μW/cm2 (3.271 mA/cm2) at optimized parameters. • Printed circuit board (PCB) bioelectrodes and PDMS microchannel were integrated. • Improved MWCNT electrodes architecture was developed on PCB bioelectrodes. • A microfluidic microbial fuel cell (μ-MFC) was realized for energy harvesting. • Optimal Volumetric bacterial and flow rate studies have been performed. • The developed μ-MFCs generates maximum power density of 239.2 μW/cm2. [ABSTRACT FROM AUTHOR]

Conventionally, highly conductive reduced graphene oxide (rGO) is synthesized by chemical reduction of graphene oxide (GO) solution using strong toxic reducing agents. However, GO itself is synthesized using strong acids and oxidants, with repetitive cleaning and laborious steps. To overcome such challenges, this work demonstrates a novel solution to the age-old rGO synthesis route by proposing a GO free, single-step, and ultrafast rGO fabrication on paper via blue light laser irradiation, named LIrGO, for direct use in papertronic applications. Such LIrGO was thoroughly characterized, and the results were completely consistent with the conventional approach. Without any post-processing, like thermal heating or cleaning, a high carbon to oxygen ratio (7.1), narrow microfibres with mesoporous granular linked morphological structure, good electrical conductivity, and minimal sheet resistance of about 23 Ω sq−1 were obtained within few minutes based on design dimensions. With such LIrGO, various circuits and complex designs can be printed directly on paper, leading to realize environmentally friendly papertronic devices. Herein, a paper-based capacitive touch sensor was validated for excellent touch response. Further, the resulting LIrGO on paper can be hand-scraped to create composite materials for other applications. The scrapped LIrGO was leveraged to investigate the absorption capacities of PVA/rGO/Sponge and rGO/Sponge coatings over a few cycles for selective separation of oil from an oil-water emulsion. The proposed method is a beginning for a new era of rGO fabrication at a single-step avoiding all the toxic chemical routes. [Display omitted] • For the first time, production of reduced graphene oxide (rGO) without graphene oxide or graphite has been demonstrated. • Blue Diode Laser was irradiated to produce rGO on paper substrates with the desired designed patterns. • The one-step efficient approach avoids toxic chemicals and tedious processes. • The proven applications include environmentally friendly papertronic devices, capacitive touch sensor and an effective oil-water separation. [ABSTRACT FROM AUTHOR]

Sustainable power generation for portable electronic devices is of high interest due to increasing energy demands. Miniaturized biofuel cells are well-reported for this purpose where ubiquitous fluids, like glucose or lactate, can be leveraged. However, such biofuel cells need enzymes to complete the catalysis, leading to many prevalent issues like the longevity of enzymes, complicated immobilization, additional mediators etc. Therefore, non-enzymatic glucose biofuel cells (NEGBFCs) are gaining interest due to their cost-effectiveness, high repeatability and excellent stability. However, based on our best knowledge such glucose biofuel cells are not reported in microfluidic environment, and therefore their potential is not exploited. Realization of the functionality of such NEGBFCs in a microscale is crucial to replace them with their enzymatic counterparts. In this work, for the first time, a microfluidic non-enzymatic glucose biofuel cell (μNEGBFC) is developed on a paper-based platform using metallic catalysts. The catalysts for electrocatalytic energy generation is fabricated using electrodeposition method and their detailed physicochemical characterizations are done. The μNEGBFC is capable of producing a power density of 12.5 μW/cm2 with a stable potential of 410 mV. This green power output can be used to operate low-power micro-devices and lab-on-chip sensors in a more continual and viable manner. [Display omitted] • A simple, cost-effective electrodeposition technique was used for electrode fabrication. • Gold deposited anode and copper deposited cathode were used as electrodes. • A paper-based Microfluidic Non-Enzymatic Biofuel Cell (μNGBFC) was constructed. • The developed μNGBFC generated a power density of 12.5 μW/cm2. • The μNGBFC was capable of retaining 56% of the initial power after 72 h. [ABSTRACT FROM AUTHOR]

Research to build origami Aluminum (Al)-air fuel cell with high energy throughput is immensely motivated from its diverse application domains. To this end, continued research into the development of economical and mass-produced bioelectrodes has been one of the major challenges. Herein, for the first time printed origami and array-type Al-Air fuel cell, with customizable porous cathode, has been demonstrated without additional catalyst. Without the need for further modification and post-processing treatment, the customized porous cathode was printed using a rapidly prototyped tabletop PCB inkjet printer. The readily available food wrapping Al foil was used to make an anode. The developed Al-air fuel cell is not only miniaturized in size, simple to produce and economical, but also capable of generating excellent electrochemical performance. With an optimized porous cathode structure and electrolytes, the open circuit potential (OCP) of two series connected Al-air fuel cell was measured to be 2.62 ± 70 V, and maximum power density of 1.024 ± 53 mW/cm2 at 1 V was witnessed. In addition, for higher polarization performance, it can be integrated in array-type configuration (series/parallel) on the similar pieces of paper. Such a novel array-type Al-air fuel cell, with simple porous cathode, has great potential for powering various flexible and personalized devices. [ABSTRACT FROM AUTHOR]

Herein, Microfluidic Paper-based Analytical Devices (μPAD) strips, also called microstrips, have been fabricated using a fused-deposition modeling (FDM) based 3D printer. A polycaprolactone (PCL) filament on a chromatography paper was harnessed to create hydrophobic boundaries of a microchannel. A pair of screen-printed electrodes, with known separation, were integrated on the microchannel to measure the time taken for fluid automatically. A mini electronic sub-system, amenable to connect with an android smartphone, consists of an easily programmable microcontroller, Bluetooth module and voltage booster circuit. The pluggable-and-playable disposable microstrip was utilized to measure the viscosity of various biological samples with an accuracy of >92% with respect to a benchtop viscometer. In particular, the protein denaturation of Bovine Serum Albumin (BSA) and Lysozyme, and viscosity variation of human saliva have been observed. With a competency to measure the viscosity between 0.5 cP to 10 cP, platform cost of 92%. [ABSTRACT FROM AUTHOR]

3D-printed portable devices have immense and proven potential to transform the field of electrochemiluminescence (ECL) for diverse biochemical applications. 3D printing (3DP) offers unparalleled ability to build tiny devices in a single step with high accuracy and compatibility, and integrability as per the requirement. In this study, for the first time, a six-well 3D-printed closed bipolar electrochemiluminescence (3DP-CBPE-ECL) device has been successfully fabricated and validated by performing single-step detection of various biochemicals such as glucose and choline. Luminol/H2O2-based enzymatic reactions were performed with optimized parameters for selective sensing of glucose and choline. The single-step detection of glucose and choline was accomplished for the linear ranges of 0.1 to 10 mM and 0.1 to 5 mM, with a limit of detections (LODs) of 24 µM and 10 µM, respectively. A smartphone was leveraged to execute multiple activities such as powering the ECL device, capturing ECL images, and calculating the ECL intensity of the obtained ECL signal. The feasibility of a six-well 3DP-CBPE-ECL device was tested by sensing glucose and choline simultaneously in a single device at three different concentrations. Furthermore, the concentration of glucose and choline was calculated in real blood serum using the conventional additive (spiking) method, demonstrating the high practicability of the fabricated ECL device and yielding promising findings. Finally, based on the obtained results and other advantages such as low-cost, fast prototyping and requirement of a minimum sample volume, the fabricated six-well 3DP-CBPE-ECL device has shown potential to be used in the field of biochemical applications. [ABSTRACT FROM AUTHOR]

In fluid rheological studies, viscosity measurement is one of the most significant phenomena leveraged in a variety of studies. Viscometers are broadly employed in a wide range of sensing and monitoring applications, such as biochemical diagnostics and numerous adulteration detections. Therefore, it is pertinent to develop a miniaturized, automated, and cost-effective device that can measure the fluid viscosity from small samples. In this work, for fluid viscosity measurements, a new low-cost automated electro-microfluidic viscometer (EMV) has been fabricated on a hydrophilic laser-induced graphene (LIG) platform with integrated electronics to monitor viscosity from a small sample of fluid of $1.5~\mu \text{L}$. The principle of operation of the fabricated device is based on the modified Hagen–Poiseuille equation, which imitates the Ostwald viscometer. Under laminar flow, the proposed standalone and portable device automatically evaluates the travel time of fluid with high accuracy. This travel time was used to obtain viscosity accurately of various fluids, such as water, milk, and acetic acid, with a minimum error of up to ±1.08%. Overall, the device provides a pathway for a convenient, robust, and plug-and-play platform for different applications, including various adulteration monitoring and biosensing. [ABSTRACT FROM AUTHOR]

Electrochemiluminescence (ECL) plays a vital role in the development of point-of-care testing (POCT) devices. Conventional electrochemical and bipolar electrochemical-based ECL systems are time-consuming, expensive, and required more fabrication steps. To eliminate such challenges, in this work, for the first time, novel laser-induced graphene (LIG)-based single electrode (SE) system has been developed, and its application in enzymeless ECL detection of multiple analytes has been validated. SEs were fabricated over polyimide (PI) substrate by directing CO2 laser leading to the creation of graphene over PI in a single step by optimizing the speed and power of the laser. Android smartphone was effectively used to provide dual functioning such as capturing the ECL image and driving the LIG-SE-ECL sensor. With optimized parameters, determination of hydrogen peroxide (H2O2), D-glucose (G), xanthine (X), and dopamine (D) was carried in the linear range from 0.1 to $70~\mu \text{M}$ , 0.1 to $70~\mu \text{M}$ , 0.1 to $100~\mu \text{M}$ , and 0.1 to $100~\mu \text{M}$ , with a limit of detection (LOD) 1.71, 3.76, 1.25, and $3.40~\mu \text{M}$ , respectively. An interference study was performed and it was observed that LIG-SE-ECL device showed effective selectivity for different analytes with their respective voltages. The developed miniaturised, low-cost ECL platform can be suitably used in many diverse applications such as POCT, environmental monitoring, and multiple biomedical applications. [ABSTRACT FROM AUTHOR]

In recent years, rising need of microfluidics-based point-of-care devices has led to cost-effective solutions at or near the location of patients. With this motivation, herein, laser-induced graphene (LIG)-based electrochemiluminescence (ECL) system loaded with U-shaped bipolar electrode (U-BPE) has been developed and its application for enzymeless sensing of various biomarkers has been validated. Low-cost and easily available flexible polyimide (PI) sheet has been effectively used for the fabrication of LIG U-BPE ECL device. With optimized speed and power, the ablation of CO2 laser on PI has been carried out to create graphenized driving electrodes and U-BPE in a single step. A cost-effective and portable 3-D printed platform has been developed for image sensing of ECL signals. The bulky power supply was effectively replaced by a dual-functional android smartphone to provide power to the LIG U-BPE ECL sensor and to capture the ECL signals. With this mini-platform, determination of various analytes, such as H2O2, D-glucose, lactate, and choline, has been accomplished in a linear range of 0.1–50, 0.1–70, 1–100, and 1– 100 μM with limit of detection (LOD) of 4.36, 2.51, 5.32, and 4.01 μ M, respectively. An interference study has been performed and it was found that after adding interfering compounds in analytes, ECL signal intensity was reduced to less than 5%. Hence, it was proven that LIG U-BPE ECL device was very selective to different analytes concerning to their voltages. [ABSTRACT FROM AUTHOR]

The present work establishes a simple, customized, and economical laser-induced graphene (LIG) material produced using a CO 2 laser. The one-step LIG bioelectrodes have been further validated for Enzymatic Biofuel Cell (EBFC) application by integrating them into a microfluidic device, fabricated by the conventional soft-lithography on Polydimethylsiloxane (PDMS). This electrode and device manufacturing technology delivers a simple and quick fabrication method, which eliminates the necessity of any further amendment and post-processing. LIG electrodes were created at optimized CO 2 laser (5.1 W power and 0.625 cm s−1 speed) irradiation which has been further modified by Multi-walled carbon nanotubes (CNT), called C-LIG electrodes, which offers improved performance and enzyme stability. In this novel study, CNT functionalized LIG electrodes have been incorporated into a microfluidic device for biofuel cell applications. LIG and C-LIG bioelectrodes have been integrated into a microfluidic device under the laminar fluid flow regime and the electrochemical and polarization study of the platform have been carried out. This C-LIG bioelectrodes integrated microfluidic device, without any metal catalyst, generated 2.2 μW/cm2 power density with an optimized 200 μl/min flow rate which is 1.37 times higher than the LIG bioelectrodes. Such novel and simple EBFC platform is amenable to further improvement for generating even more power output by optimizing the LIG formation, alternate nano-functionalisation and mediator based electrochemical analysis. • A separator-free biofuel cell generating power by the biocatalysis of enzymes. • Highly flexible Laser induced graphene electrodes were fabricated by CO 2 laser. • Bioelectrodes were integrated with PDMS based microchannel. • Improved enzyme immobilization by surface functionalisation of bioelectrodes. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance (AMR) is a global health threat, progressively emerging as a significant public health issue. Therefore, an antibiotic susceptibility study is a powerful method for combating antimicrobial resistance. Antibiotic susceptibility study collectively helps in evaluating both genotypic and phenotypic resistance. However, current traditional antibiotic susceptibility study methods are time-consuming, laborious, and expensive. Hence, there is a pressing need to develop simple, rapid, miniature, and affordable devices to prevent antimicrobial resistance. Herein, a miniaturized, user-friendly device for the electrochemical antibiotic susceptibility study of Escherichia coli (E. coli) has been developed. In contrast to the traditional methods, the designed device has the rapid sensing ability to screen different antibiotics simultaneously, reducing the overall time of diagnosis. Screen-printed electrodes with integrated miniaturized reservoirs with a thermostat were developed. The designed device proffers simultaneous incubator-free culturing and detects antibiotic susceptibility within 6 h, seven times faster than the conventional method. Four antibiotics, namely amoxicillin–clavulanic acid, ciprofloxacin, ofloxacin, and cefpodoxime, were tested against E. coli. Tap water and synthetic urine samples were also tested for antibiotic susceptibility. The results show that the device could be used for antibiotic resistance susceptibility testing against E. coli with four antibiotics within six hours. The developed rapid, low-cost, user-friendly device will aid in antibiotic screening applications, enable the patient to receive the appropriate treatment, and help to lower the risk of anti-microbial resistance. [ABSTRACT FROM AUTHOR]

Microfluidic devices with integrated electrodes, called electromicrofluidic (EMF) device, have been reported for multiple applications. In this work, a unique approach to realizing a multilayered EMF device, with microchannel and integrated electrodes on the same polyamide (PI) substrate, has been presented. A computer-controlled CO2 laser ablation method, with varying speeds and power values, was employed to form laser-induced graphene (LIG) on a PI substrate as per the desired design. Initially, to create a microchannel layer, the formed LIG was peeled off which left behind an etched pattern. Subsequently, to realize an electrode layer, the PI substrate with microchannel was further ablated to create patterned LIG. An optimal flow rate of 100~μ L/min via a controlled syringe pump was established in EMF device. As a prototype, the developed platform, with microchannel and electrodes, was explored for variable electrochemical applications. First, the electrochemical sensing of uric acid displayed a limit of detection (LOD) as 0.61~μ M in a linear range from 10~ μ M to 3 mM with significant recovery values. Furthermore, the polarization performance for fuel cell application was evaluated on the developed EMF platform using the chronoamperometry (CA) method with a stable open-circuit potential (OCP), harnessing the maximum power density obtained was 3.027 nW/cm2. Finally, an array of interdigitated microelectrodes (IDEs) was realized to examine impedance-based nitrite detection. Overall, the presented multilayered EMF devices with microchannel and electrodes on the single sheet authenticate the applicability of the designed platform for a variety of sensing and energy harvesting applications. [ABSTRACT FROM AUTHOR]

Development of economical and mass-manufacturable bioelectrodes with desirable physical properties is one of the crucial challenges to realize automated and robust enzymatic biofuel cell (EBFC). This article focuses to develop customized CO2 laser-induced flexible graphene (LIFG) bioelectrodes on the polyamide substrate. The cost-efficiency and customization of LIFG bioelectrodes have been further demonstrated for EBFC application by integrating them into a microfluidic device, fabricated by the conventional soft lithography on polydimethylsiloxane (PDMS). First, the LIFG bioelectrodes were created at optimized CO2 laser (power and speed) irradiation, and characterization was performed to ensure the existence of graphene material. Subsequently, the surface morphological study of the noninduced polyamide sheet, LIFG, and LIFG with the relevant enzyme (GOx and laccase)-modified bioelectrodes has been characterized. Finally, various voltammetric electrochemical analyses of the modified LIFG bioelectrodes have been accomplished. After such an electrochemical study, the bioelectrodes were integrated into the microfluidic device and a power density of 13 μW /cm2 (52μA/cm2) was harnessed at an optimized fluid rate of 200μL/min. By using this fabrication method, the proposed LIFG bioelectrodes have shown excellent potential for electrochemical redox and polarization performance in a microfluidic environment, with a huge scope to enrich the power output by introducing the additional cofactor-based electrochemistry and device stacking. [ABSTRACT FROM AUTHOR]

Miniaturization of enzymatic biofuel cell has become a crucial factor especially towards device fabrication and integrated bioelectrode system. When successful in a cost-effective manner, it can be used as a source of qualitative electric power for portable and implantable devices. The present work demonstrates the design and fabrication of cost-effective, portable, miniaturized microfluidic enzymatic biofuel cell (M-EBFC) using rapid prototyping 3D printing (3DP) technique. The low cost, radially available, non-toxic Pencil Graphite Electrodes (PGE's) were used as the electrode material. Various grades of PGE's were rigorously studied, by screening separately and cohesively for both anodic and cathodic sides, and the optimized ones (B and 5H for anodic and cathodic sides respectively) have been utilized. These PGE's successively encapsulated into Y-shaped microchannel, fabricated using a commercial 3D Printer. This platform, integrating 3D printing technology and PGE's, delivers simplistic, cost-effective and quick fabrication method, which eradicates the necessity of any further amendment and post-processing. Furthermore, the enhancement of the surface area and electrochemical sensing, PGE's were coated with carboxylated multiwalled carbon nanotube followed by the covalent immobilization enzymes. The electrochemical and polarization performance was compared between both HB and the optimized PGEs. The optimized PGE based 3D printed microfluidic membraneless enzymatic biofuel cell (3DP-MM-EBFC) showed open circuit potential (OCP) of 0.433 V and with a maximum power density of 18 μW cm−2 at a current density of 60 μA cm−2. This rapidly prototyped 3D printed fabrication technology demonstrates the viability of simple and advanced microfabrication techniques to build well-organized plug-and-play devices to power several portable low-power microelectronic devices and sensors. • Microfluidic Membraneless Enzymatic Biofuel Cell is presented. • 3D printed rapid prototyping integrated with optimized grade pencil bioelectrodes is harnessed to fabricate the device. • Device performance is assessed at various flow rates and sustainability was measured. • Such device is amenable to demonstrate the feasibility to operate low-power devices. [ABSTRACT FROM AUTHOR]

Viscometers are broadly employed in a wide range of sensing and monitoring applications, such as biochemical optimization, biomedical diagnostics, pharmaceuticals, and various adulteration detections. When realizing them in a microfluidic environment, the viscometers can potentially be used in an automated and robust point-of-care setting. Even after so much evolution, one of the constant challenges faced in the development of microfluidic devices is to choose the best fabrication scheme, particularly, in terms of a simplified process, cost, and time. Here, we present a 3-D-printed electro-microfluidic viscometer (EMV) which mimics the conventional Ostwald viscometer. The EMV measures the reference fluid viscosity, under laminar flow, by automatically evaluating the travel time of the sample fluid vis-à-vis to that of a reference fluid. The EMV, consisting of a microchannel and four equidistance electrodes, was fabricated using a simple desktop fused deposition modelling 3-D printer in a single step. The complete platform, comprising of the microfluidic device, pumping subsystem, data acquisition subsystem, and signal processing subsystems, has been integrated and automated to determine the viscosity. [ABSTRACT FROM AUTHOR]

Futuristic microfluidics will require alternative ways to extend its potential in vast areas by integrating various facets such as automation of different subsystems, multiplexing, incorporation of cyber-physical capabilities, and rapid prototyping. On the rapid prototyping aspect, for the last decade, additive manufacturing (AM) or 3D printing (3DP) has advanced to become an alternative fabrication process for microfluidic devices, enabling industry-level abilities towards mass production. In this context, for the first time, this work demonstrates the fabrication of monolithic multilayer microfluidic devices (MMMD) from planar orientation (1 layer) to nonplanar (4 layers) monolithic microchannels. The developed MMM device was impeccable for synthesizing highly potentialized silver nanoparticles (AgNPs) in <1 s. Moreover, the transport of chemical species with laminar flow simulations was performed on the process along with the thorough characterizations of produced AgNPs, finding the mean AgNPs particle size of around 35 nm without any post-processing requirements. The well-known catalytic activity of AgNPs was leveraged to enhance weak chemiluminescence (CL) sensing signals by >1300 %, increasing CL sensitivity. Further, machine learning (ML) predictive models encouraged to obtain the experimental parameters without human intervention iterations for target-specific applications. The proposed methodology finds the potential to save resources, time, and enables automation with rapid prototyping, providing possibilities for mass fabrications. [Display omitted] • Alternative to conventional planar microfluidic device fabrications. • Monolithic leakproof multilayer microchannel fabrication process. • An insight into Microfluidic-enabled nanomaterial synthesis. • Silver nanoparticle synthesis in < 1s with zero post processing. • Enhancements in chemiluminescence signals and machine learning predictions. [ABSTRACT FROM AUTHOR]

In this work, we study the effects of treating nanostructured SnO2–SiO2 films derived by a sol-gel method with nitrogen and oxygen plasma. The structural and chemical properties of the films are closely investigated. To quantify surface site activity in the films following treatment, we employed a photocatalytic UV degradation test with brilliant green. Using X-ray photoelectron spectroscopy, it was found that treatment with oxygen plasma led to a high deviation in the stoichiometry of the SnO2 surface and even the appearance of a tin monoxide phase. These samples also exhibited a maximum photocatalytic activity. In contrast, treatment with nitrogen plasma did not lead to any noticeable changes in the material. However, increasing the power of the plasma source from 250 W to 500 W led to the appearance of an SnO fraction on the surface and a reduction in the photocatalytic activity. In general, all the types of plasma treatment tested led to amorphization in the SnO2–SiO2 samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fully portable smartphone-based CL device is presented. • A LIG heater integrated into a 3D printed chip for localized incubation conditions. • 3D printed single-use µPADs as detection substrates. • It is clinically validated for ALP-level detections in human serum samples. • In the near future, the developed CL device will uphold multiple applications. Point-of-Care (PoC) devices have become the fundamental requirement for rapid diagnostics and quantitative analysis at locations convenient to patients. This work reports a fully portable, pocket-friendly, self-powering, and temperature-controlled 3D printed chemiluminescence (CL) device. Moreover, the CL device leveraged the omnipresent smartphone as a detector unit to capture the CL signals. The device also contains a removable magnetic locking smartphone holder, making it universal. Further, the CL device integrates a microfluidic µPAD based detection methodology to monitor the abnormal levels of crucial bio-analyte alkaline phosphatase (ALP). The alkaline phosphatase (ALP) hydrolysis reaction with l -Ascorbic acid 2 phosphate releases a by-product, ascorbic acid (AA). The produced AA is a radical scavenger that quenches the CL signal, thereby facilitating the detection of ALP. Excellent performance of the developed CL device was observed in detecting the ALP with good linearity ranging from 1 mU/L to 10 mU/L and a detection limit of 0.59 mU/L. Subsequently, the device was tested for real-time ALP detection in human blood serum samples. Interestingly, the obtained results were less than 7 % error, compared to clinical samples. The developed fully portable 3D printed CL device with integrated electronics can be a future benchmark for mass production of susceptible devices in detecting various analytes. [ABSTRACT FROM AUTHOR]

Electronic components for energy storage need to be mechanically conformable to ensure maximum wearer comfort, flexibility, and good thermal stability in different environments. Hence, the development of supercapacitors (SCs) as an alternative to micro‐batteries for use in microelectronics applications is currently receiving much scientific attention. This work presents an adaptable, cost‐effective, and efficient method to fabricate flexible laser‐induced graphene (LIG) supercapacitor electrodes using a CO2 laser. LIG formation and morphology have been studied and confirmed through energy dispersive X‐ray (EDX) spectroscopy and scanning electron microscopy (SEM) techniques. The interdigital laser‐induced graphene electrodes are fabricated and optimized for SCs on a flexible substrate. These SCs have the advantages of charge‐discharge cycles, capacitive performance, high power density as well as long cyclic life. For LIG electrodes, the suitable electrolyte is optimized to control the electrochemical properties of supercapacitors, such as charge transfer, flexibility, and stability. Hence, a supercapacitor composed of 3D porous laser‐induced graphene with PVA‐KOH gel electrolyte is fabricated, with 83.33 mF/cm2 areal capacitance at a constant current density of 0.5 mA/cm2. The energy density 4.62 μWh/cm2 and power density 0.2 mW/cm2 are observed at a 0.5 mA/cm2 constant current density. The capacitance of the proposed SC increases with an increase in certain temperatures and shows excellent performance. This flexible SC could be a high potential for use in energy storage and wearable device applications. [ABSTRACT FROM AUTHOR]

Electronic devices with multifunctional capabilities is forever an attractive area with diverse scope including towards developing solutions to sustainable energy technology. Microbial biofuel cells (MiBFCs) are one such sustainable energy technology based electronic device which can not only harvest energy, but can perform biosensing leading to bioremediation. However, low energy yield, costly fabrication procedures and bulky devices are some of the limitations of such MiBFCs. In this work, for the first time a simple vacuum filtration fabrication technique is used for making thin and conductive electrodes with homogeneous CNT solution for MiBFC application. The fully paper-based MiBFC is integrated into a compact micro device with 3D printed components which adds novelty to the work. The MiBFC is capable of maintaining a stable open circuit voltage of 410 mV for more than 1 h and can deliver a maximum power density of 192 μW/cm2 which is reasonably high for such paper-based MiBFCs operating with micro-volume of substrate. This device will help in developing more freestanding power sources for instant diagnostics and data transfer. • A simple vacuum technique was used to prepare carbon electrodes on paper. • The fabricated cost-effective electrodes were used for microbial fuel cell (MFC). • Oxygen reduction reaction on the cathode was enhanced with MnO 2 nanoparticles. • A 3D printed device was fabricated to enclose the MFC. • The MFC delivered a power density of 192 μW/cm2 for more than an hour. [ABSTRACT FROM AUTHOR]

By providing a facile and scalable alternative to otherwise complex and resource-intensive synthesis of graphene, laser-induced graphene (LIG) is spearheading the translation of graphene-based propositions to deployable technologies for societal benefit. LIG is a versatile and economical synthesis approach which is being used on a variety of substrates and in a multitude of applicationsâ€"including miniaturized sensing systems. One aspect that has not been addressed thoroughly in LIG-based miniaturized sensing systems is its successful integration with microfluidics and its possible use in point-of-care settings. To further diversify the applications of LIG with integrated microfluidics, this work reports on the development of an integrated flexible microfluidics-LIG based electrochemical biosensor. The work describes the methodology to develop a polydimethylsiloxane-LIG scribed polyamide microfluidic device in a leakage-free flexible application. In view of the excellent electrical and electrochemical properties of LIG, such device has been employed for electrochemical biosensing. The biosensing capabilities of the microfluidic device were validated via sensing of cardiac troponin Iâ€"a gold standard cardiac biomarker for early identification of acute myocardial infarction (AMI). The developed biosensor demonstrated a detection and quantification limit of 45.33 pg mlâˆ'1 and 151.10 pg mlâˆ'1 respectively, which are in clinically significant ranges for diagnosis of AMI. The µ -fluidic biosensor was also analyzed for stability and interference with other cardiac biomarkers. The developed integrated µ -fluidic electrochemical biosensor was evaluated for possible point-of-source applications in conjunction with a custom 3D printed peristaltic pump and smartphone-enabled miniaturized potentiostat. [ABSTRACT FROM AUTHOR]

Macro to nanoscale energy scavengers is emerging as a promising solution to tackle the problems of energy shortage caused due to increasing world population and limited availability of energy resources. The capability of the miniaturized scavengers to harvest ambient energy like vibrations, mechanical motions, and body motions makes them an efficient alternative to clean energy solutions. This paper reviews the works done in the field of piezoelectric and triboelectric energy scavengers, the authors briefly described different types of scavengers, recent state-of-the-art designs, operating modes, performance comparisons, and future scope considering critical evaluation which can help the researchers to decide their work approach in the field of energy scavenging. The authors also speculate on how future advances in 3D printing technology and textile base energy scavenging could aid in the creation of wearable electronics. Energy scavengers will surely replace many energy sources in the coming future and will be proven to be a trailblazing method in the field of environment-friendly energy generation. [ABSTRACT FROM AUTHOR]

There is an imperative need of developing new strategies and models for meeting the swelling demand of electricity in developing nations like India. One of the promising models for this would be Decentralized Distributed Generation (DDG). DDG locates the power generating source closer to the consumer utilizing locally available Renewable Energy (RE) resources, thereby decreasing the Transmission and Distribution (T&D) losses. Despite the numerous advantages with DDG, there have been some minor issues preventing its large scale deployment and utilization in India. This paper discusses the various technology options which can be used for DDG in India and the problems which the Indian power sector has been facing for a long time. This paper aims to provide a complete analysis of the best possible RE based technology options for DDG in India along with their cost of generation, benefits, barriers, applications, and the possible pathways for its deployment. [ABSTRACT FROM AUTHOR]

• Demonstrated Internet of Things enabled Home Energy Management System. • Introduced programmable load categorization for peak load management. • Assessed Home Energy Management System based on energy usage pattern survey. • Surveyed to evaluate consumer readiness for Demand Response. • Resulted in cost savings up to 49% with fixed and 53% with Time of Day tariff. Residential power consumption has surged with the widespread adoption of smart appliances, prompts utilities to implement Demand Response(DR) programs. Home Energy Management Systems (HEMS) plays a vital role in these initiatives within the smart grid infrastructure. The rapid advancement of wireless communication technologies, especially the Internet of Things (IoT), will enable successful architectural designs for HEMS. This study proposes an incentive-based DR implementation using IoT-enabled HEMS for the Indian residential sector that represents 25% of the total power demand. The proposed HEMS automates the management of categorized loads during peak hours through load shifting and scheduling. The proposed algorithm is deployed in real-time residential setup using IoT modules. Emphasizing sustainability and consumer affordability, the work integrates a Photo-Voltaic (PV) based Battery Storage System (BSS) to support critical loads during peak hours. Consumer load preferences obtained through a survey are incorporated into the deployment of the proposed HEMS. Experimental studies demonstrated significant energy savings of 49% with the loads under consideration and substantial cost savings like approximately 49% with Load Management (LM) alone, 53% with the inclusion of Time of Day (ToD) tariff, and an impressive 78% with the proposed incentives for participating in DR. Additionally, this study highlights the synergistic savings realized through the combined implementation of the proposed LM strategy and ToD tariff in India. [ABSTRACT FROM AUTHOR]

The concoction of microfluidics and IoT to realize Point-of-Care (PoC) diagnostic devices have become of great interest in the present world. Urea is the biomarker for diseases such as pre-eclampsia, hepatic encephalopathy, chronic renal failure, hepatocellular carcinoma, different types of cancers, various kinds of viral infections, etc. Ammonia is associated with parkinsonism, muscle wasting, sarcopenia, osteoporosis, etc. Hence their detection is beneficial in the healthcare sector. Herein, an IoT-enabled microfluidic-based colorimetric device has been developed to detect and quantify both ammonia and urea in blood serum. The entire device casing was 3D printed, and the microfluidic chip was fabricated using poly (dimethylsiloxane) and glass. Incorporation of Node MCU as the microcontroller provided the device with enhanced capabilities for data recording and transmission, even in remote areas. The device was capable of detecting ammonia and urea in a wide range. The ammonia was detected in the range of 0.5–10 mg L-1 with a limit of detection (LoD) of 0.1879 mg L-1, while the urea was detected in the 100–500 mg L-1 range with a LoD of 21.4091 mg L-1. The developed device was 3D printed, portable, miniaturized, IOT enabled, and cost-efficient, with a power consumption of a mere 5 V, thus opening new avenues in sustainable point-of-care diagnostics. Moreover, the device was added with offline and online data visualization capabilities, thus increasing its user-friendliness. [Display omitted] • IoT-enabled colorimetric device for detection of ammonia and urea in blood serum. • Urea and ammonia detection require 10 µL and 200 µL serum samples, respectively. • LoDs of 0.1879 mg L-1 and 21.4091 mg L-1 are suitable for physiological range. • The device is amenable to monitoring environmental ammonia and urea. [ABSTRACT FROM AUTHOR]

• An optomicrofluidic colorimetry device has been developed. • The device was enabled with IoT and Bluetooth modules, and a microcontroller. • Two of the soil macronutrients i.e. nitrogen and phosphorus were determined. • The analytes were detected selectively with excellent limit of detection. • A mobile app was developed for short range data monitoring and transmission. With the amalgamation of microfluidics and cyber-physical systems, a paradigm shift can be witnessed in the way the devices are conceptualized and developed for many applications, including soil and water monitoring for agricultural application and overall environmental monitoring. Such technological enhancements are leveraged to facilitate on-site detection and quantification by developing miniaturized devices offering multiplexed detection and data transmission across the globe using internet of things (IoT). Herein, a colorimetry-based miniaturized device was developed by incorporating optoelectronic components and employing a poly(dimethylsiloxane) (PDMS) microfluidic device for precise determination of two of the soil macronutrients i.e. nitrogen and phosphorus. Miniaturization and online data monitoring using the IoT and Bluetooth-based modules, along with Arduino microcontroller, lead to generate data, and its monitoring and storage even in the remote locations. Nitrite and phosphorus were detected in a linear range of 1 µM–30 µM and 10 µM–100 µM with limit of detection (LOD) of 0.33 µM (0.021 ppm) and 0.75 µM (0.095 ppm) respectively which is above the prescribed limits. Furthermore, an android app was developed for continuous monitoring using Bluetooth module for short range data transmission. Overall this work demonstrates the microfluidic colorimetric sensing and IoT enabled data monitoring of soil macro nutrients through a cost-effective platform which opens up avenues for the development of miniaturized point-of-care devices. [ABSTRACT FROM AUTHOR]

• Fabricated the efficient M−I−M configured pure BFO-based thin film photovoltaic devices using wet chemistry and cost-effective processing. • Measured highest efficiency (ȵ = 0.89%), reported so far, in single layered BFO devices. • Detailed investigation on defect states and Urbach energy tail in BFO. • Investigated the role of oxygen annealing on structural, optical and electrical properties. • Propose a hypothetical model to understand the carrier transportation in a better way. • Demonstrated the forward and reverse bias conditions of the prepared M−M−M devices. We report enhanced photovoltaic efficiency in optimized monolayer BiFeO 3 (BFO) thin-film based solar cells prepared by inexpensive spin-coating technique. The short circuit current density and open-circuit voltage of the single-layer BFO cell were measured to be 1.91 mA/cm2 and 0.92 V, respectively, which is much higher than the reported values so far in monolayer BFO based photovoltaic systems. The influence of oxygen annealing on photovoltaic response is investigated, and a further improvement in photo-current density is reported. The phase purity and average crystallite size are examined by X-ray diffraction studies, which confirmed the single-phase formation of rhombohedrally distorted perovskite BFO structured layer deposition. The average crystallite size, as determined by the Williamson-Hall method, is found to be in the range of 14 – 17 nm. The micrographs reveal a uniform and crack-free deposition of both the thin-films. The cross-sectional images reveal the smooth film deposition of thicknesses in the range of 360 – 370 nm. The average bandgap values of the air and oxygen annealed films are found to be 2.57±0.02 eV and 2.64 ± 0.02 eV, respectively. The oxygen annealing of these films show a significant reduction in Urbach energy tail values from 0.37 ± 0.02 eV to 0.28 ± 0.03 eV, which suggests a lower density of defect states in the oxygenated films. The X-ray photoelectron analysis showed a noticeable reduction in Fe2+ ions, hence supporting the Urbach energy studies. We also demonstrate a metal–semiconductor-metal model to explain the enhancement in short-circuit current density, suggesting that the main driving force for the photo-generated charge carriers is the Schottky field at the interfaces rather than the inherent polarization field in the as-deposited (unpolled) BFO films. [ABSTRACT FROM AUTHOR]

• Microfluidic laser-induced graphene (LIG) based taste sensor is presented. • Interdigitated electrodes and microchannel were integrated on the same platform. • LIG-IDE device manifests lower detection limit than the human sensing threshold. • Selectivity of the device toward different analytes have been achieved. • The device provides a low-cost, point-of-care solution for diverse applications. [Display omitted] On-site taste monitoring is important for human health, and widespread adoption requires low-cost, easy-to-fabricate technology and very precise portable equipment. The portability and high sensitivity of the device are regulated by the electrode configuration and, in turn, the fabrication techniques employed. In this context, herein, sensitive and specific electrical detection of five human gustative sensory tastes leveraging unique properties of graphene to realize optimized electrodes is presented. Herein, first, a Microfluidic device with integrated microchannel and Interdigitated electrodes (IDEs), based on a capacitive sensing mechanism, was prepared by the laser-induced graphene (LIG) technique. Electrochemical Impedance Spectroscopy (EIS) characterized the performance of the LIG-IDE microfluidic device. Under microfluidic conditions, the impedance change was linearly varying for the concentration of different chemicals in the range of 1–1000 ppm, and a minimum detection limit of 1 ppm was obtained. A comparison of the differences in capacitive response by LIG-IDE sensor for the five chemicals related to various tastes was also performed at different concentrations with respective real samples. This microfluidic taste sensor has the potential to provide low-cost, simple-to-integrate multi-functional point-of-care sensors for human sensory tastes, clinical, and environmental applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mini 3D Printed multichannel Electrochemiluminescence (ECL) platform is presented. • The platform has closed bipolar (C-BPE) and driving electrodes (DEs). • Laser induced graphene (LIG) on polyamide sheet was used to create the electrodes. • A smartphone was utilized to capture ECL signal and power the ECL device. • Real samples of Vitamins B12 and C were detected at once with excellent recovery. Herein, a two and three-channel laser-induced graphene (LIG) based closed bipolar Electrochemiluminescence (LIG-C-BPE-ECL) system was developed for sensing various analytes. Polyimide sheet was extensively used to fabricate two and three-channel LIG-C-BPE-ECL device as it has the ability to produce graphitized zones in a single step. CO 2 infrared laser, with optimized parameters, was effectively used to fabricate closed bipolar (C-BPE) and driving electrodes (DEs). A miniaturized portable 3D printed system was developed to hold the device and place the smartphone to create a standalone ECL sensing platform. The smartphone not only captured the ECL signal but also powered the ECL device through DC to DC buck-boost converter. Two and three-channel LIG-C-BPE-ECL device was fabricated for the sensing of both individual and two analytes at the same time. The performance of the two-channel LIG-C-BPE-ECL device was validated by doing individual sensing of Hydrogen peroxide (H 2 O 2), Vitamin B 12 and Vitamin C for the linear range of 0.5–100 μM, 0.5–1000 nM and 1–1000 μM with a limit of detection (LOD) 0.303 μM, 0.109 nM and 0.96 μM respectively. Subsequently, three-channel LIG-C-BPE-ECL device was fabricated and simultaneous detection of Vitamin B 12 and Vitamin C was accomplished. Finally, real sample analysis has been performed by doing concurrent sensing of vitamin B 12 and vitamin C using three-channel LIG-C-BPE-ECL device with a good recovery rate. Such a miniaturized portable LIG-C-BPE-ECL system has great potential to be used in various applications including point of care testing. [ABSTRACT FROM AUTHOR]

Summary: Herein, ferroelectric Ti‐doped BiFeO3 (BFTO) heterojunction photovoltaic (PV) cells are realized for underwater PV applications. In the heterostructure, NiO functions as a transparent wide‐bandgap (3.2 eV) hole transport layer (HTL), whereas BFTO is the visible energy harvester and the highly conductive WS2 behaves as the electron transport layer (ETL). The multijunction PV device with a cell area of 1cm2 revealed a current density (JSC) and an open‐circuit voltage (VOC) of 1.90 mA/cm2 and 1.20 V, respectively, under ambient conditions (before submerging into water). Subsequently, the polydimethylsiloxane (PDMS)‐encapsulated Ag/NiO/BFTO/WS2/ITO PV device was investigated for underwater solar energy harvesting in a shallow tank. For a comparative analysis, the mono‐junction NiO/BFTO and BFTO/WS2 PVs were also evaluated. The results indicated a steady decrease in the efficacy and power density of the cell with depth, and the heterojunction PV has outperformed the single‐junction PVs. As there are spectral variations with increase in depth, the heterostructure seem to have the potential to absorb the overall spectrum as NiO being transparent transmits high energy UV radiations into the device, while BFTO and WS2 layers absorb the visible and NIR spectrum. Therefore, the device though submerged can capture the solar energy efficiently with minimal losses in terms of spectrum and function efficiently. These results establish that the ferroelectric nano‐heterostructured PV devices can be utilized as a power generating source for various low‐power marine‐based sensing applications. [ABSTRACT FROM AUTHOR]

Microfluidic paper based microbial fuel cells (μP-MFCs) have gained considerable popularity due to their compact, quick and low-cost fluid manipulation paradigm. Compared to conventional technologies, paper as a substrate with advanced nanomaterial electrode material has many distinct advantages from point-of-care monitoring to energy harvesting. As a result, these have been used and are more popular in a variety of fields, such as health diagnostics, environmental and food quality management. By this encouragement, herein a portable microbial fuel cell as an origami array has been demonstrated using custom carbon electrodes with a modified the transition metal oxide MnO 2 nanomaterial. This customized electrode design was first printed using a tabletop PCB inkjet printer where the anode was further modified with synthesized MnO 2 nanoparticles. The entire cell was formed by folding the paper along predefined edges where the fuel, Shewanella putrefaciens , was streamed continuously via inherent capillary cation. Various studies, such as morphological, surface catalyst coating, amount loading and volumetric culture optimization experiments, have also been accomplished to find the most appropriate optimum parameter to enhance power conversion efficiency. The developed origami arrayed microbial fuel generated an open-circuit potential (OCP) for two parallel connected MFCs of 0.534 V and a maximum power density of 15.9 μW/cm2 with a maximum current density of 130 μA/cm2. In the end, the harvested power was used by powering the digital watch circuit through the ultra-low DC-DC booster board. Such an MFC origami array, with simple electrode manufacturing and modification process, has a great potential and bright future in Internet of Things (IoT) applications by making multiple stacks where the data can be monitored. [Display omitted] • Origami array-type MFC with printed electrode was fabricated by a PCB inkjet printer. • Several surface modification and loading (MnO 2 and bacteria) optimizations were done. • The developed device generates a maximum power density of 17.5 μW/cm2. • The device was used to power a digital watch using DC-DC booster. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ferroelectricity was established in 5% Ti-doped BiFeO 3 with 2 eV bandgap. • WS 2 and CuCrO 2 form n-type electron and p-type hole transport layers respectively. • The efficiency was improved by 100 orders or more as compared to plain BFO. • Integration of ETL and HTL facilitate efficient charge separation and transfer process. • A series connection of two transparent PV unit cells has been demonstrated. The transparent nature of photovoltaic (PV) cell can replace the windows and facades in conventionally integrated buildings to harvest energy from natural sunlight and spontaneously generate electric power for various mankind applications. To demonstrate this idea, Ti-doped BiFeO 3 (BFTO) lead-free ferroelectric material was explored as an active material in Pt/CuCrO 2 /BFTO/WS 2 /ITO PV cell where WS 2 formed the n-type electron transport material (ETL), an unconventional p-type CuCrO 2 was responsible for the hole-transportation (HTL) and bottom ITO and Pt top electrodes, were employed to extract the electrical properties of the device. A single heterojunction PV unit yielded a large short-circuit current density (J SC) and an open-circuit voltage (V OC) of 2.60 mA/cm2 and 0.95 V, respectively, which resulted in an improved efficiency of 100 orders or more as compared to the plain BFO based PVs. Different structural and absorption studies performed on 5% and 10% Ti-doped BFO revealed lower bandgap for 5% (2 eV) and thus higher absorption in visible region. The elevated ferroelectricity in 5% BFTO along with the indispensable driving force offered by ETL and HTL promoted enhanced band bending and thus efficient carrier separation and extraction in the heterostructure. A well-defined band diagram was proposed to explain the PV operating mechanism. For the integration of the transparent PV, a series connection of two 1 × 1 cm PV unit cells has been demonstrated to offer a significant amount of photogenerated voltage. This establishes the prospects of ferroelectric heterojunctions to realize PV power generation sources for emerging electronic applications. [ABSTRACT FROM AUTHOR]

The efficacy of droplet-based microfluidic assays depends on droplet size, pattern, generation rate, etc. The size of the droplet is affected by numerous variables as flow rate ratio, viscosity ratio, microchannel geometry, surfactants, nature of fluids and other dimensionless numbers. This work reports rigorous analysis and optimization of the behavior of droplets with change in flow rate ratio and viscosity ratio in a flow-focusing device. Droplets were produced for different flow rate ratios maintaining a constant aqueous phase and varying the continuous phase, to have capillary numbers ranging from 0.01 to 0.1. It was observed that the droplet size decreased with the increase in flow rate ratio, and vice versa. It was noted that as the viscosity ratio was increased, the dispersed phase elongated before the complete breakup and long droplets were formed in the microchannel. Smaller droplets were formed for lower viscosity ratios with a combination of higher flow rate ratios. An empirical relation has been developed to predict the droplet length in terms of capillary number and flow rate ratio for different viscosity ratios. In addition, microparticle encapsulation in individual droplets was attempted to realize the effect of flow rate of the continuous phase for various flow rate ratios on encapsulation efficiency. [ABSTRACT FROM AUTHOR]

Nanoparticles have become omnipresent as they have distinctively diverse properties from their bulk counterparts. They find a considerable research interest in numerous biological, biomedical, biopharmaceutical, and biochemical applications. The productivity and structure of nanoparticles are deeply reliant on the method used for their synthesis. The classical hydrothermal method needs massive and expensive temperature controller instruments, a huge amount of reagents, and specific autoclaves for their synthesis. With this motivation, herein, an automated, integrated, and miniaturized thermal monitoring system has been designed and developed for producing nanoparticle-on-chip (NoC) in a microfluidic platform. Herein, Zinc oxide (ZnO) nanoparticles were synthesized. The device comprises a microcontroller, self-designed switching circuit, cartridge heater, and thermocouple. The device, with dimensions $78 \times 75 \times 40$ mm3, has benefits such as portability, easy-to-use, amenability to geotagged data logging, and inexpensive. The device showcased the temperature sensitivity of ± 0.5 °C. A polymethyl methacrylate (PMMA)-based microfluidic device, with a suitable microreactor, was fabricated using the CO2 laser ablation technique. ZnO nanoparticles were successfully synthesized at 95 °C within 60 min and were subjected to several characterization techniques to manifest their crystographic, elemental, morphologic, and spectroscopic properties. As a proof-of-principle, the produced ZnO nanoparticles were validated for electrocatalytic sensing of hydrazine and uric acid, and as a catalyst in an enzymatic glucose biofuel cell (EBFC) to test its efficiency. The proposed microfluidic thermal system can be utilized for carrying out numerous temperature-based reactions and analyses. [ABSTRACT FROM AUTHOR]

Leveraging laser-induced graphene (LIG) in various flexible polymer electronics applications is becoming tremendously popular. LIG is porous multilayer graphene generated by a single-step process using infrared CO2 laser onto the carbon-based polymers. In this article, a direct LIG printed microstrip patch antenna operating at the 5.8-GHz unlicensed band is presented. Based on simulations, the proposed design exhibited the desired unidirectional radiation characteristics with a measured gain of 1.82 dBi at the resonant frequency. The LIG-based rectangular patch was printed using the CO2 laser by selective reduction of polyimide (PI) sheet. The chemical properties of LIG were examined using various structural and morphological characterization techniques, which confirmed the formation of multilayer graphene. The sensitivity of the patch antenna was analyzed for measuring strain and its effect on LIG. By harnessing LIG on flexible material such as PI sheet, the antenna exhibited a threshold increase in sensitivity. The proposed sensor shows a sensitivity of 14.08 and 11.34 for compressive and tensile strain, respectively. Inspired by the significant sensitivity, the fabricated device has been examined for human motion monitoring by attaching it to the human hand for practical usage in real-time applications. The proposed antenna-based sensor reduces the number of components by eliminating external wiring and onboard battery. Moreover, it serves as both the sensing and wireless data transmitting element. Overall, this work demonstrates designing a compact, easy-to-fabricate, sensitive, and flexible antenna-based Internet of Things (IoT) sensor for motion detection, structural health monitoring, and industrial strain sensing applications. [ABSTRACT FROM AUTHOR]

The effective incorporation of novel and highly conductive hybrid functional nanomaterials onto flexible and porous substrates is extremely desirable to develop flexible supercapacitors. Herein, a novel 2D/0D-MoS2/SnS2 on a flexible cellulose paper substrate has been demonstrated for its utilization in flexible supercapacitors. The surface morphology and particle size of the MoS2 and SnS2 QDs, elemental composition, absorption spectra, and crystallinity have been analyzed thoroughly. Further, to explore the supercapacitor applications, the electrochemical response has been studied. The obtained results demonstrate that both the pristine MoS2 and MoS2/SnS2 QDs composites on cellulose paper exhibited excellent electrochemical performance. The specific capacitance for the pristine MoS2 and MoS2/SnS2 QDs displayed 422.2 F g−1 and 277.1 F g−1 at 0.5 A g−1 current density using a conventional two-electrode system. The drop-casting of SnS2 QDs provides better electrochemical active sites, which contributed to the enhanced specific capacitance of the composite structure. Moreover, it is shown that cellulose paper as an electrode material, using MoS2 and MoS2/SnS2 QDs, is applied as a supercapacitor for potential utilization in wearable electronics applications. [ABSTRACT FROM AUTHOR]

Controlled, stable and uniform temperature environment with quick response are crucial needs for many lab-on-chip (LOC) applications requiring thermal management. Laser Induced Graphene (LIG) heater is one such mechanism capable of maintaining a wide range of steady state temperature. LIG heaters are thin, flexible, and inexpensive and can be fabricated easily in different geometric configurations. In this perspective, herein, the electro-thermal performance of the LIG heater has been examined for different laser power values and scanning speeds. The experimented laser ablated patterns exhibited varying electrical conductivity corresponding to different combinations of power and speed of the laser. The conductivity of the pattern can be tailored by tuning the parameters which exhibit, a wide range of temperatures making them suitable for diverse lab-on-chip applications. A maximum temperature of 589 °C was observed for a combination of 15% laser power and 5.5% scanning speed. A LOC platform was realized by integrating the developed LIG heaters with a droplet-based microfluidic device. The performance of this LOC platform was analyzed for effective use of LIG heaters to synthesize Gold nanoparticles (GNP). Finally, the functionality of the synthesized GNPs was validated by utilizing them as catalyst in enzymatic glucose biofuel cell and in electrochemical applications. [ABSTRACT FROM AUTHOR]

Summary: Paper microfluidic devices are innovative platforms for building miniaturized devices for energy harvesting, energy storage, and sensing applications. Such devices are reported to be used as membraneless microfluidic fuel cells to power portable electronic in a pump‐less manner by leveraging the embedded capillaries and co‐laminar flow. This paper demonstrates fabrication and characterization of the high‐performance metal‐free aluminum‐air microfluidic paper fuel cell (AAMPFC). Herein, aluminum foil acts as an anode, buckypaper with built‐in multiwalled carbon nanotubes (MWCNTs) acts as a cathode and sodium hydroxide (NaOH) works as an electrolyte. The novel AAMPFC is analyzed with various electrolyte concentrations, and maximum output voltage, current density, and power density are recorded. This easy‐to‐fabricate AAMPFC platform, costing less than US$ 0.5, is further optimized to achieve peak energies by stacking four AAMPFCs (in series and parallel) with various concentrations of electrolyte (NaOH). With parallel configuration, maximum open‐circuit potential (OCP), peak current (mA/cm2), and power density (mW/cm2) of 1.32 V, 50.67 mA/cm2 and 22.80 mW/cm2, respectively, are observed with optimized electrolyte, while with series stacked configuration, a stable OCP of 4.10 V is measured. In a series configuration, AAMPFC generated sufficient power to powering a scientific calculator with LCD display for 3 days and 11 LEDs for 10 hours continuously. This research work provides a significant method to enhance the output power with inexpensive parameters (buckypaper, single paper microchannel) to power portable electronic devices. Further, the performance can be enhanced by investigating AAMPFC with various grades of aluminum foil in combination with different grades of porous cellulose papers. [ABSTRACT FROM AUTHOR]

Herein, a glassy carbon electrode (GCE) modified with a hybrid of crude black pepper-graphitized mesoporous carbon (GCE/GMC@pep) for an electrochemical detection of hydrazine is presented. The GCE/GMC@pep shows a surface-confined redox peak at an electrode potential E 1/2 = + 235 mV vs.Ag/AgCl in pH 7 PBS with a surface excess value Ʈ e-pep = 13.19 × 10−9 mol−1 cm2. The physico-chemical characterization unveils the interaction of GMC with piperine. Further, GCE/GMC@pep manifests a highly selective electro-catalytic activity towards Hydrazine in neutral pH at +257 mV in a linear detection range of 70 μM-7 mM with lower limit of detection of 40 μM(with cyclic voltammetry) and 30 μM-5 mM with lower limit of detection of 0.5 μM (with chronoamperometry). More so, the fabricated electrode system provides an insignificant interference from co-existing biochemical / chemicals. Real samples, tobacco, cigarette smoke, lake water and human blood serum, are further analyzed via standard addition approach. Overall, this study describes a prototype module for tuning the redox active behavior of selective phytochemical for electrochemical sensing applications. • Electrochemical activity of the piperine, from crude black pepper as a hydrazine sensor. • Piperine is entrapped over a graphitized mesoporous carbon matrix. • Hydrazine sensing mechanism was very selective with a detection limit of 40 μM. • Interference from other co-existing biochemicals was negligible. • The electrode was successfully tested for real sample of Hydrazine. [ABSTRACT FROM AUTHOR]

There has been a surge in the use of transdermal drug delivery systems (TDDS) for the past few years. The market of TDDS is expected to reach USD 7.1 billion by 2023, from USD 5.7 billion in 2018, at a CAGR of 4.5%. Microneedles (MNs) are a novel class of TDDS with advantages of reduced pain, low infection risk, ease of application, controlled release of therapeutic agents, and enhanced bioavailability. Biodegradable MNs fabricated from natural polymers have become the center of attention among formulation scientists because of their recognized biodegradability, biocompatibility, ease of fabrication, and sustainable character. In this review, we summarize the various polysaccharides and polypeptide based biomaterials that are used to fabricate biodegradable MNs. Particular emphasis is given to cellulose and its derivatives, starch, and complex carbohydrate polymers such as alginates, chitosan, chondroitin sulfate, xanthan gum, pullulan, and hyaluronic acid. Additionally, novel protein-based polymers such as zein, collagen, gelatin, fish scale and silk fibroin (polyamino acid) biopolymers application in transdermal drug delivery have also been discussed. The current review will provide a unique perspective to the readers on the developments of biodegradable MNs composed of carbohydrates and protein polymers with their clinical applications and patent status. [ABSTRACT FROM AUTHOR]

Several commonly known physiological analytes, such as ascorbic acid (AA), dopamine (D), uric acid (UA), and xanthine (X), are known to have significant impact on human metabolism. Therefore, it is quite imperative to develop a miniaturized, multiplexed, noninterfering, and inexpensive sensing platform to monitor these compounds. Reminiscing this, herein, a miniaturized electrochemical sensing platform over a poly methyl methacrylate substrate has been depicted for specific and selective sensing of AA, D, UA, and X. First, to create three electrode zones for electrochemical sensing, three microchannels were engraved on a PMMA sheet by CO2 laser ablation process. Subsequently, these microchannels were filled with suitable electrode materials leading to a miniaturized electrochemical sensing platform. In the present article, the Toray carbon gas diffusion layer was the working electrode (WE), while screen-printed conductive carbon paste and silver chloride (Ag/AgCl) ink served as the counter electrode and the reference electrode, respectively. The electrocatalytic oxidation of these analytes exhibits an excellent electro-catalytic oxidation behavior. The effect of variable concentrations and interference from the coexisting analytes was also examined. The linear concentration ranges for these compounds (AA, D, UA, and X) under the optimized parameters were 100–1000, 40–1000, 20–1000, and 10– 100 μM, respectively, while the detection limits were 89.65, 38.94, 18.71, and 9.01 μM}correspondingly. The platform was also tested with real human serum samples. Such a multiplexed and miniaturized electrochemical sensing platform can be used in point-of-care devices for simultaneous sensing of multiple analytes. [ABSTRACT FROM AUTHOR]

The present work demonstrates a miniaturized, easily fabricated, environment-friendly, and cost-effective Microfluidic Paper-based Microbial Fuel Cell (MPMFC) as a potential Energy Harvesting Device. The device consists of a microchannel with a reductant (Shewanella putrefaciens exoelectrogen bacterium with L.B Broth) and oxidant (aerated tap water) flowing over Carbon electrode (anode) and Silver electrode (cathode) using co-laminar flow with the self-capillary phenomenon. The electrochemical analysis like Polarization, Open Circuit Voltage (OCV) was evaluated using a potentiostat, and conductivity and sheet resistance were evaluated using a four-point probe instrument. Various bacterial studies, like growth curve study (Optical Density), volumetric concentrations, and incubation time, were carried out to find out the best suitable optimal bacterial conditions. Lastly, detailed element composition study and morphology of the surface of the electrode with biofouling was carried out using Energy Dispersive Spectroscopy (EDS) and Scanning Electron Microscopy (SEM) techniques, respectively. The portable MPMFC yields a maximum power density of 15.4 μW/cm2 (1340 nA/cm2) at 390 mV over 90 μL of culture. Also, An Internet of Things (IoT)/cloud-based hardware has been developed and integrated with MPMFC platform to observe the real-time device performance leading to its long-lasting potential to operate miniaturized microelectronics sensors and portable devices. • A miniaturized Membraneless Paper-based Microbial Fuel Cell has been discussed. • The device has been powered by Shewanella Putrefaciens exoelectrogen bacterium. • Various studies were performed to find out the best suitable bacterial conditions. • Rigorous electrochemical analyses were evaluated to explore the device outputs. • Maximum power density of 15.40 μW/cm2 (1.34 μA/cm2) at 390 mV was obtained. [ABSTRACT FROM AUTHOR]

The sensitive and accurate detection of glucose and lactate is essential for early diagnosis and effective management of diabetes complications. Herein, a 3D Printed ECL imaging system integrated with a Smartphone has been demonstrated to advance the traditional ECL to make a portable, affordable, and turnkey point-of-care solution to detect various human metabolites. A universal cross-platform application was introduced for analyzing ECL emitted signals to automate the whole detection process for real-time monitoring and rapid diagnostics. The developed ECL system was successfully applied and validated for detecting glucose and lactate using a single-electrode ECL biosensing platform. For glucose and lactate detection, the device showed a linear range from 0.1 mM to 1 mM and 0.1 mM–4 mM with a detection limit (LoD) of 0.04 mM and 0.1 mM, and a quantification limit (LoQ) of 0.142 mM and 0.342 mM, respectively. The developed method was evaluated for device stability, accuracy, interference, and real sample analysis. Furthermore, to assist in selecting the accurate and economic ECL sensing platform, SE-ECL devices fabricated via different fabrication approaches such as Laser-Induced Graphene, Screen Printing, and 3D Printing are studied for the conductivity of electrode and its significance on ECL signal. It was observed that emitted ECL signal is independent of the electrical conductivity for the same concentration of analytes. The findings suggested that the developed miniaturized point-of-care ECL platform would be a comprehensive and integrated solution for detecting other human metabolites and have the potential to be used in clinical applications. • 3D Printed smartphone integrated portable ECL platform has been realized. • Single Electrode ECL devices were fabricated using three methods. • Detection of human metabolites was performed alongwith various sensory parameters. • A Graphical User Interface was introduced for real-time and rapid diagnostics. • Machine Learning algorithm was harnessed to seamlessly predict various biomarkers. [ABSTRACT FROM AUTHOR]