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Snake bite is a serious medical emergency often leading to untimely fatalities. Serotherapy is the only treatment method adapted for this, whose efficacy depends on identification of the Snake species and venom type. As a specific antivenom has to be implicated for saving the victim, in most of the cases, such identification is challenging, thus, leading to mortality due to delay in treatment or side effects of injecting polymeric non-specific antivenom. Therefore, a point-of-care, venom specific detection device could be an impactful diagnostic tool. Herein, a prototype of miniaturized electrochemical sensing platform is presented for detection of Crotaline, venom from various common pit viper snakes. A three electrode based micro-platform with carbon fibre microelectrode, modified with mesoporous carbon, embedded and laminated in commercial OHP sheet, has been developed. The dimensions of the miniaturized platform was 25 mm × 35 mm, size of electrode was 0.5 mm × 25 mm with an electrochemical testing zone of diameter 10 mm, electrode spacing as 3 mm. The microscopic characterization revealed immobilization of porous carbon on fine fibrous structure. The device gave highly stable and sensitive electro-catalytic oxidation of Crotaline at E'= at 0.81 V, and provided a linear range of 50-300 μM, limit of detection as 18.98 μM and limit of quantification as 63 μM. The device exhibited negligible interference from physiological blood serum biochemicals, high stability and reproducibility. Further, real blood serum samples, analysis via standard addition approach, was performed which showcased appreciable recovery values confirming the practical applicability of the device.

Engineering a cost-effective, flexible electronic device in a one-step fabrication process is quite challenging to perform. Herein, we have introduced a simple, low-cost, solid-state process for producing and printing of complex circuits using Laser-Induced Graphene (LIG). In the present work, LIG has been effectively and selectively formed from direct CO2 laser ablation on a polyimide sheet. Varying CO2 laser power and speed, the electrical conductivity of the LIG has shown a linear increment in the conductivity measurement. The laser-induced samples were structurally characterized using Scanning Electron Microscopy (SEM), EDX, X-ray Photoelectron Spectroscopy (XPS), Raman spectroscopy. The results show a one-step method to create Graphene-derived structures on the polyimide sheet surface. This method of generating LIG on a flexible substrate (polyimide sheet) offers an easy way to fabricate Laser-Induced Flexible electronics (LIFE) circuits. Using this, the feasibility and the realization of a capacitive touch sensor and liquid level sensor has been successfully demonstrated. Further, as a prototype system, the LIG was examined for the H2O2 electrochemical sensing application. It gives an appreciable response for the detection of H2O2 in comparison to other carbon-based electrodes with limit-of-detection (LOD) as $0.3~\mu \text{M}$ in a linear range from $1~\mu \text{M}$ to 10 $\mu \text{M}$ .

Evidently, any alternation in the concentration of the essential DNA elements, adenine (A), guanine (G), cytosine (C), and thymine (T), leads to several deformities in the physiological process causing various disorders. So, to realize a simple and precise technique for simultaneous determination of the DNA elements continue to remain a challenge. Microfluidic devices offer numerous advantage, such as low volume consumption, rapid response, highly sensitive and accurate real time analysis, for point of care testing (POCT). Herein, a microfluidic electrochemical device has been developed with three electrodes fabricated using a carbon-thread microelectrode (CTME) for DNA elemental detection. CTME, functionalized with graphitize mesoporous carbon (GMC), worked as a working electrode, bare CTME functioned as an auxiliary electrode while CTME coated with Ag/AgCl ink performed as a reference electrode. The developed device was used for evaluating individual DNA elemental base pairs simultaneously using various electrochemical techniques. The anodic peak current obtained for the DNA bases were 0.56 ± 0.04 V (G), 0.92 ± 0.02 V (A), 1.09 ± 0.05 V (T) and 1.24 ± 0.04 V (C) in a potential window of 0.2 V to 1.5 V. The device was corroborated for simultaneous sensing, and detection limits were found to be [Formula: see text] (G), [Formula: see text] (A), [Formula: see text] (T) and [Formula: see text] (C) in the linear range of [Formula: see text] - [Formula: see text]. Finally, the device was successfully used for instantaneous determination of DNA bases in the human blood serum sample. Overall, this work demonstrates the use of a simple microfluidic device with CTMEs for electrochemical determination of DNA bases amenable for POCT.

Herein, a simple, miniaturized and low-cost electrochemical sensing platform integrated with three-electrode system has been presented. A two-layer microfluidic device has been fabricated entirely on a PMMA sheet using a CO2 laser. Pencil graphite electrode (PGE), chemically modified electrode with a nanocomposite of MWCNT@polysterene-chitosan (PGE/MWCNT@PS-CS) as a working electrode (WE), PGE coated with Ag/AgCl ink as a reference electrode (RE) and a plain PGE as a counter electrode (CE) were inserted into the microreactor with reagent consumption of 2 mL. As a proof of concept, the analytical performance of the developed microfluidic electrochemical sensor was investigated for non-enzymatic glucose sensing. Highly selective, non-interfering sensing of glucose in presence of various bioanalytes, was obtained. The nanocomposite lead to an exceptional limit of detection as 0.309 nM. With fine-tuning and electrode surface modification, the designed miniaturized platform could be used for diverse electrochemical biosensing application.

Microfluidic paper-based analytical devices ( $\mu $ PADs) are a clean-room free, cost-effective, and self-pumping flow-based rapid prototyping technique, which is compatible with a varying range of fluids. Until now, $\mu $ PADs have been primarily fabricated using crayons, and plotting-machine and solid-ink printers. These devices can be easily employed for various detection schemes, such as electrical, electrochemical, and optical. The presence of a capillary effect in the chromatograph paper has made $\mu $ PADs independent of a passive device, such as pumps and valves. In this paper, an alternative and a novel method is proposed to achieve the $\mu $ PADs effortlessly using a 3-D printer (3DP), which has many advantages over the existing methods. For creating hydrophobic barriers for microchannel walls, polycaprolactone (PCL) filament was used with fused-deposition modeling (FDM) 3DP. PCL filaments were deposited on the chromatography paper followed by heating for determining the overall dimension and depth of the microchannel at which PCL melts and penetrates into this paper. The $\mu $ PADs are characterized and optimized for two parameters. First, fabrication parameters, such as heating temperature and time duration, were used for the creation of the hydrophobic barrier using a hot air oven. Second, the microchannel parameters, such as microchannel width, boundary thickness, chromatography paper grade, and microchannel source shape (rectangular, triangular, and circular) were used for the fluid-flow by measuring the time taken by fluid to travel a fixed length of the microchannel. After rigorous analysis, it was found that for the creation of the hydrophobic barrier, $\mu $ PADs heated between temperature 120°C to 150°C require 30 min. Under optimized conditions for the fluid flow, the chromatography paper grade 1441 with a triangular source microchannel was found to be best. This paper provides an alternate, simple, and optimized method toward the development of the application-specific $\mu $ PADs, such as the micro-viscometer, which, in turn, can be widely used to monitor various types of fluids including human bodily fluids.

The present work demonstrates a miniaturized 3D printed Electrochemiluminescence (ECL) sensing platform with Laser-Induced Graphene (LIG) based Open Bipolar Electrodes (OBEs). To fabricate OBEs, polyimide (PI) substrate has been used as it provides properties like low-cost fabrication, high selectivity, great stability, easy reproducibility, cost-effectiveness and rapid prototyping. Moreover, graphene can be created on PI in a single step during the ablation of the CO2 laser. Android smartphone was efficiently used to sense ECL signals as well as to drive the required voltage to the OBEs. With the optimized parameters, the imaging system was successfully used to detect Hydrogen Peroxide (H2 O2) with a linear range of 1 $\mu \text{M}$ to $100~\mu \text{M}$ and detection of limit (LOD) $5.8729~\mu \text{M}$ (R2 = 0.9449, n = 3). In addition, the detection of glucose has been carried out with a linear range of $1~\mu \text{M}$ to $100~\mu \text{M}$ and detection of limit (LOD) $0.138~\mu \text{M}$ (R2 = 0.9875, n = 3). Further, real samples were tested to manifest the workability of the platform for random samples. Overall, the developed low-cost, rapidly realized and the miniaturized system can be used in many biomedical applications, environmental monitoring and point-of-care testings.

A microfluidic paper-based analytical device (μ-PAD) and handheld colorimeter android application for quantifying the precise concentration of adulterants in milk are developed. A simple method to pattern polydimethylsiloxane for creating a hydrophobic barrier on filter paper using custom-designed rubber stamp containing the design of μ-PAD was used. The experiments were performed for the detection of urea, starch, salt and detergent ranging from 1 to 100 mg in 10 ml of milk. The user just needs to pipette drops of adulterated milk on a test spot and the results are obtained instantly. The authors believe that the developed platform can be used as a basis for low-cost, portable system for various fluid adulterants’ tests. The experimental database was used for the development of a colorimetric android application to calibrate the colour range for adulterants’ concentration detection. The limit of detection of colorimetric android application for adulterants urea is 5 mg, starch is 17 mg, salt is 29 mg and for detergent is 20 mg in 10 ml of milk. This kind of system is attractive for use in developing countries, in the field, or as an inexpensive alternative as compared with other methods for water and food safety.

Various research activities related to profiling chemicals employ detection or measurement of the response from a specimen in terms of electric fields or currents. Hence, a portable poly-potential device forms one of the necessary measuring equipment essential to these domains. This work aims to propose a Poly-Potential Portable Potentiostat (P4), that can perform electrochemical analysis of solutions through easily integrable data-acquisition hardware and flexible software post-processing. The P4 device is based on a commercial development board, which provides an analog front-end (AFE) for working with 2-lead and 3-lead amperometric cells. An economical and portable design approach is prioritised while keeping the basic functions of the research-grade commercial instruments. A novel technique of dynamically changing the bias and reference potential is used to achieve a finer resolution, enabling qualitative estimation. P4 works by performing detailed mathematical post-processing on-board and therefore relies on hardware integrity as much as on software flexibility. Calibration of P4 was done using a standardised solution to function independently of any external hardware or software tools. P4 makes electrochemical analysis truly portable in remote or resource-constrained applications.

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 E1/2 = + 235 mV vs.Ag/AgCl in pH 7 PBS with a surface excess value Ʈe-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.

In recent times,extensive research isbeing carried out for the development of simple, low-cost point-of-care microfluidic platforms for electroanalytical applications. Microfluidic devices (μFDs) are very attractive in the field of clinical, food and environmental analysis owing to their advantages over conventional method likeless reagent consumption and rapid analysis[1-3].Polymerand paper stands out to be most potential substrate for fabricating such devices that require being in contact with bodily fluid such as blood, serum and urine depending upon their biocompatibility, flexibility and ease-of-use [4-5]. The integration of such disposable μFDs with electrochemical analysis gives new capabilities and functionalities that enables detection of several compounds with high accuracy. Polymersubstrates are known for its transparency, flexibility, non-absorbent and toughness properties. Screen-printing has become popular for disposable electrochemical sensor to prepare carbon conductive pathway [6].For printing, the carbon structures are well dispersed in liquid, and variousink parameters, like density, viscosity and surface tension, need to be carefully evaluated.Even though screen printed electrode (SPE) offers high performance and reliability but the high electrical resistance, produced due to the polymer binders, leads to non-uniform electrode surface and affect the performance of the device[7]. Owing to this limitation, use of carbon/graphene paper as a simple alternative to develop disposable electrochemical sensor. However, mechanical transfer of carbon/ graphene layer to the flexible substrate is an essential step towards a simple transfer technique. Herein, a novelrealization of disposable electrochemical sensor is presented by using recyclable polymer material as an alternative to produce low-cost electrochemical sensor with buckypaper (BP) as an electrode material. The polyethyleneterephthalate(PET) obtained from drinking bottle were used as sensing platform.BP is a flexible self-supporting material of entangled assembles of multi-walled carbon nanotube with outstanding electrochemical, mechanical and piezoresistive properties leading to broad range of application in lithium-ion batteries, fuel cells and Solar cells. The CO2 laser was used for producing sensing substrate and desired three electrode pattern of BP, and was attached on the PET substrate using double side tape. The lamination process was used to define the geometric area and for insulating the electrode. The determination of Xanthine(Xn) and Uric Acid (UA) were chosen as a proof of concept with unmodified BPsurface.Xn and UA are produced during purine metabolism wherein Xn is an intermediate product whileUA is a final product present in tissues and bodily fluids like urine and blood. Xn produces final purine metabolite, leads to abnormality in UA level which is responsible for various diseases symptoms. The electrochemical behaviour of Xn and UA were studied using cyclicvoltammetry (CV), differential pulse voltammetry(DPV) and chronoamperometery (CA) The anodic peak for Xn and UA were observed at 0.4 V and 0.12 V.The calibration curve for Xn and UA were obtained in the linear range 30µM- 500µM and 50 µM- 1000µM respectively by CV. The limit of detection (LOD) obtained for Xn and UA was 23µM and 38µM respectively. Finally, the proposed method was applied for simultaneous determination of Xn and UA in human serum sample with good selectivity and high sensitivity. The disposable micro-electrochemical sensor provides a new approach for the fabrication of new sensing platform and has broad range of application for simultaneous detection of various analyte forpoint-of-care analysis. References [1]‘Beebe, David J., Glennys A. Mensing, and Glenn M. Walker. "Physics and applications of microfluidics in biology." Annual review of biomedical engineering 4.1 (2002): 261-286. [2]Nilghaz, Azadeh, et al. "Flexible microfluidic cloth-based analytical devices using a low-cost wax patterning technique." Lab on a Chip 12.1 (2012): 209-218.. [3]Salve, Mary, et al. "Greenly synthesized silver nanoparticles for supercapacitor and electrochemical sensing applications in a 3D printed microfluidic platform." Microchemical Journal 157 (2020): 104973. [4]Songjaroen, Temsiri, et al. "Blood separation on microfluidic paper-based analytical devices." Lab on a Chip 12.18 (2012): 3392-3398. [5]Hou, Guanglei, et al. "Ultratrace detection of glucose with enzyme-functionalized single nanochannels." Journal of Materials Chemistry A 2.45 (2014): 19131-19135. [6]Mettakoonpitak, Jaruwan, et al. "Electrochemistry on paper‐based analytical devices: a review." Electroanalysis 28.7 (2016): 1420-1436. [7]Adkins, Jaclyn A., and Charles S. Henry."Electrochemical detection in paper-based analytical devices using microwire electrodes." Analytica chimicaacta 891 (2015): 247-254. Figure 1

Herein, Silver nanoparticles (AgNPs) decorated pencil graphite electrodes (PGEs), with assimilation of Chitosan (CS), as a versatile electrode material for supercapacitor and electrochemical sensing application have been reported. The AgNPs were prepared by employing a green synthesis method using marigold flower s extract. Marigold flower contains lutein, which can be used as a reductant. The morphology and crystal structure of the prepared nanomaterial was characterized by Field emission scanning electron microscopy (FESEM), Elemental Dispersive X-Ray Spectroscopy (EDX), Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), UV-VIS Spectrophotometer and X-ray photoelectron spectroscopy (XPS). The prepared hybrid material, PGE/AgNPs/CS was utilized in an electrochemical 3D printed microfluidic device for supercapacitor and electrochemical sensing of H2O2. As a supercapacitor, the device provided a remarkable storage capacity of 367.16 mF cm−2at a current density of 1 mA cm−2 with high cyclic stability over 1500 charge-discharge cycle. Subsequently, H2O2 sensing with the same electrode in a three-electrode microfluidic system gave a LOD of 0.52 µM within a linear range of 1-10 µM. In addition, the effect of common interfering species, including ascorbic acid (AA), uric acid (UA) dopamine (DA) and xanthine (XN) were thoroughly investigated. Thus, the prepared hybrid electrode material showed excellent electrochemical activity for the supercapacitor and electrochemical sensing of H2O2, which can be further assessed for other relevant applications.