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The foremost objective of this work is to prepare a novel electrochemical sensor-based screen-printed carbon electrode made of zinc oxide nanoparticles/molecularly imprinted polymer (SPCE-ZnONPs/MIP) and investigate its characteristics to detect sodium dodecyl sulfate (SDS). The MIP that is polyglutamic acid (PGA) film was synthesized

A rapid, simple, and sensitive voltammetric sensor has been fabricated to determine Rhodamine B (RhB), a textile coloring agent. Silver nanoparticles (AgNPs) were synthesized by the chemical reduction method of silver nitrate and sodium citrate. Graphene nanoplatelets (GPLs) and AgNPs were drop-casted on the surface of a working electrode of a screen-printed carbon electrode (SPCE), forming the SPCE-GPLs/AgNPs samples. Scanning electron microscopy-energy dispersive X-ray and cyclic voltammetry confirmed the altered surface of the SPCE. The square wave voltammetry was used for the electrochemical determination of RhB. The SPCE-GPLs/AgNPs demonstrated electrochemical responses to detect RhB with a linear range of 2-100 μM, and the limit of detection was 1.94 μM. The SPCE-GPLs/AgNPs demonstrated a selective detection of RhB in the presence of common interfering compounds present in the food samples, including sucrose and monosodium glutamate. Furthermore, the sensor presented good reproducibility as well as repeatability in the detection of RhB. When the sensor was used to determine RhB in an actual food sample, similar results were shown as suggested by UV-vis spectroscopy analysis. Hence, the fabricated sensor can be applied for the detection of RhB in food samples.

An analytical and experimental study of nanofilm aluminum (Al) for ultra-high dynamic range surface plasmon resonance (SPR) biosensor is presented in this article. A thin film of 16 nm Al is proposed for metallic sensing layer for SPR sensor. For the protective layer, a 10 nm of gold (Au) layer was configured on top of Al as a protection layer. This ultra-high dynamic range of SPR biosensor reached the bulk refractive index sample limit up to 1.45 RIU. For the analytical study, with the assumption of anisotropic refractive indices experiment, the dynamic range showed a refractive index value of around 1.58 RIU. The refractive index value limit achieved by the proposed sensing design is potentially implemented in various applications, such as in chemical detection and environmental monitoring study with high refractive index solution sample. The experimental results are presented as a proof-of-concept of the proposed idea.

Silica has entrenched surface chemistry which allows for the surface functionalization with various functional groups, including those of biomolecules. In this study, the aim is to modify fluorescent natural silica nanoparticles (FSNP) with E.coli antibody. The precursor for fluorescent natural silica-based nanoparticles (FSNP) was obtained from a silica precipitate of geothermal power plant in Central Java, Indonesia. This offers a more cost-effective and environmentally friendly route towards the preparation of such nanomaterials. FSNP was synthesized using the sol-gel method to produce impurity-free fluorescent nanoparticles, then activated the groups to conjugate with E. coli antibodies. The surface functionality of the amines is obtained by reacting FSNP with an aminosilane crosslinker (APTES). To produce aldehyde functionality, it is further treated with glutaraldehyde. These aldehyde groups react with the amine groups of biomolecules such as antibodies to form amine bonds. Based on the BraunerEmmett-Teller (BET) analysis, the average surface area is 134.32 m2/g FTIR results showed the formation of NH2 groups after modification of FSNP with APTES at a wavelength of 1635 cm−1. The intensity of FSNP modified FSNP and APTES measured using fluorescence spectroscopy at the FSNP intensity was 688,430 a.u while the intensity of the APTES modified FSNP was 450,474 a.u. The approach of conjugating E.coli antibodies to fluorescence natural silica-based nanoparticles via the APTES crosslinker opens up the possibility of future use of the system as a biosensing platform, particularly the detection of E. coli.

The material modification of thick film sensor electrodes is being developed to enhance the performance of sensing capabilities such as stability, sensitivity, and limit detection. The utilization of graphene, ionic liquid, and Nafion has become a key factor to obtain a good material as modifiers in electrochemical sensors. This disposable modified electrode exhibits excellent current enhancement, fast electron transfer kinetics, and chemical stability properties. In this research, a screen-printed electrochemical sensor was fabricated by modifying the carbon working electrode with a combination of Nafion, ionic liquid, and graphene to determine ascorbic acid. The prototype ascorbic acid (AA) sensors show peak oxidation at a potential 0.3 V vs reference Ag|AgCl. Analytical characteristics of the prototype sensors were investigated with a linear calibration curves of AA concentrations over the range from 0.25 to 2 mM (R2 ~ 0.9912). The sensor has sensitivity around 15.95 nA M−1 cm−2 and the limit of detection was 164 μM. The cyclic voltammogram result indicate that the modified working electrode can increase the redox peak current higher than the bare working electrode. Thus, the modified electrode of thick film sensors could provide a promising platform for the sensor of ascorbic acid detection.

This paper presents a simple and low-cost ultraviolet (UV) Light Emitting Diode (LED)-based light source with uniform and controllable light intensity for portable exposure photolithography process. The system can receive user-defined parameter values for exposure dose and duration time, controlled by the microcontroller through a LED driver circuit. The measurement results show that LED has a peak wavelength of 394 nm and very narrow full-width at half maximum (FWHM) of 12.59 nm. By rotating LED array, the UV light source can produce uniform irradiance at the average 82 mW/cm2 at near-zero contact, 51 mW/cm2 at 1 cm, and 8 mW/cm2 at 5 cm. We also found that exposure time and distance of the light source to the pattern greatly affect the results of the pattern transfer on the substrate. The smallest resolution that can be exposed in this study on the Printed Circuit Board (PCB) substrate with dimension 2 × 2cm2 is 100 microns. Using the developed UV-LED light source, it shows great potential as a low-cost light source and feasible applications for microfabrication.

Forms of lead (Pb) have been insidiously invading human life for thousands of years without obvious signs of their considerable danger to human health. Blood lead level (BLL) is the routine measure used for diagnosing the degree of lead intoxication, although it is unclear whether there is any safe range of BLL. To develop a practical detection tool for living organisms, we engineered a genetically encoded fluorescence resonance energy transfer (FRET)-based Pb2+ biosensor, ‘Met-lead 1.44 M1’, with excellent performance. Met-lead 1.44 M1 has an apparent dissociation constant (Kd) of 25.97 nM, a detection limit (LOD) of 10 nM (2.0 ppb/0.2 μg/dL), and an enhancement dynamic ratio of nearly ~ 5-fold upon Pb2+ binding. The 10 nM sensitivity of Met-lead 1.44 M1 is five times below the World Health Organization-permitted level of lead in tap water (10 ppb; WHO, 2017), and fifteen times lower than the maximum BLL for children (3 μg/dL). We deployed Met-lead 1.44 M1 to measure Pb2+ concentrations in different living models, including two general human cell lines and one specific line, induced pluripotent stem cell (iPSC)-derived cardiomyocytes, as well as in widely used model species in plant (Arabidopsis thaliana) and animal (Drosophila melanogaster) research. Our results suggest that this new biosensor is suitable for lead toxicological research in vitro and in vivo, and will pave the way toward potential applications for both low BLL measures and rapid detection of environmental lead in its divalent form.

Integration between Wireless Sensor Network (WSN) and the Internet of Things (IoT) is widely used in many application to build a support system to overcome any problem. Indonesia as an agriculture country which needs that technology to solve agriculture problem such as land monitoring, water treatment, etc. Precision farming based on WSN and IoT is described in detail especially in multi-node sensor configuration and the master station. In this research, the WSN system consists of the multi-node sensor which contains several sensors for each node, a controller and wireless module. A master station is built with raspberry pi 3 (RPi3) as the main computer. All data from node sensor will be displayed to a graphical user interface (GUI) and saving data into internal databases. Communication between the master station and each node sensor through a wireless network based on X-bee board. The software operated in closed loop control to activate water treatment based threshold value from the sensor. The sensor data also displayed in server station based on the website and can be accessed in everywhere through an internet connection. A farmer can monitor updated sensor data using android application where installed in an android mobile phone.

A novel structure for this microspeaker is composed of permanent magnet Neodymium Iron Boron (NdFeB) with the magnetization of 1.42 T, diameter 1.6 mm, a thickness 0.8 mm is bonded on the PDMS membrane and N-copper planar coil is fixed on the bottom wafer. The total size of the PDMS membrane is 3 × 3 mm2 and thickness 130 μm. The proposed microspeaker is designed for CIC (completely in canal) type hearing aid. The calculation results successfully confirmed that the proposed MEMS microspeaker have a better of electroacoustic performance and efficiency. The sound pressure level (SPL) is 99 dB and the maximum displacement is 5.8 μm at the resonance frequency of 630 Hz with the microspeaker efficiency is 0.06%. In addition, the aim of this structure is to get the low resonance frequency and high acoustic efficiency is validated.

A color is a characteristic object that produces a different sensation in the eye as a result of the way the object reflects or emits light. In an RGB color system, each color is the result of a combination of 3 basic colors, namely red, green, and blue. Each base color has a density range value from 0 to 255. RGB values can be said to be a combination of red, green and blue values of a color. In the human eye has limitations in identifying a color, where the human eye cannot recognize the color changes that occur in the range of small RGB values, and cannot know the RGB value of a color. In the biomedical world, knowing the changes in color in a small range of RGB values is important. Small color changes are an indicator that can occur in an identification of a disease and other medical needs. Making an application system that can identify a color can help a problem that requires an RGB value in its completion, especially in the medical field. At this time human life cannot be separated from smartphones. Seeing the close proximity of human life to smartphones, the author made a program by utilizing an Android-based smartphone to identify colors. This program utilizes smartphone cameras. The camera will capture images of objects that will be identified. The program identifies the image and determines the RGB value of the pixel at the center point of the image. Then the combination of RGB values will be matched with the existing database and colors that match the combination. In this paper, the author explains how the design and method of the program work, how to explain the program listing and how to analyze the results of program testing.

The low quantum yield of luminescence from lanthanide-doped up-conversion nanoparticles (UCNPs) has been enhanced by using an optimized ‘gold sandwich’ with a transparent top layer and a reflecting bottom layer at 980 nm excitation. Erbium (Er)-doped UCNPs, with a NaYF4:Yb,Er core, were synthesized by a thermal decomposition process and coated with silica to assist in metal-enhanced fluorescence (MEF). A bottom layer of thick coalesced gold island film, acting as a mirror, increases the optical path length of the 980 nm radiation through the UCNP layer dispersed on it. This layer enhances the UCNPs' 540 nm green emission by a factor of 5–8 compared to that in the absence of the gold reflector. A thin nanoparticle-like gold layer on top of the UCNPs, with a surface plasmon absorption around ∼550 nm, completes the sandwich, which augments the luminescence enhancement by another factor of ∼2.5, thus taking the net enhancement factor to ∼13–19 when compared to the luminescence in the absence of the gold-sandwich. The surface plasmon absorption in the top gold layer enhances the local electric field at the UCNPs to promote their radiative decay. Compared to previous reports, mostly for the solution state, the current case study is a solid state measurement.

Human osteosarcoma cells MG-63 were cultured on anodically etched titania nanotubes (TiO2 NT), with diameters ranging from 40-100 nm, to study the correlations between cell proliferation and adhesion on the 2.5 dimensional (2.5D) extracellular matrix (ECM). Unlike other reports, mostly based on mouse stem cells, and 2D cell culture, our studies indicate that the 2.5D NT promote higher proliferation and activity, but less 2D adhesion. Proliferation of the MG-63 cells was significantly higher in the NTs, the best being the 70 nm diameter sample, compared to planar titania (control). This is consistent with previous studies. However, cellular adhesion was stronger on TiO2 NT with increasing diameter, and highest on the control as obtained from shear stress measurement, paxilin imaging, and western blot measurements probing focal adhesion kinase, p130 CAS, and extracellular-regulated kinase, in addition to cell morphology imaging by fluorescence microscopy. We provide direct videography of cell migration, and cell speed data indicating faster filopodial activity on the TiO2 NT surfaces having lower adhesion. This evidence was not available previously. The NT matrices promote cells with smaller surface area, because of less 2D stretching. In contrast, on comparatively planar 2D-like surfaces uniaxial stretching of the cell body with strong anchoring of the filopodia, resulted in larger cell surface area, and demonstrated stronger adhesion. The difference in the results, with those previously published, may be generally attributed to, among others, the use of mouse stem cells (human osteosarcoma used here), and unannealed as-grown TiO2 NTs used previously (annealed ECMs used here).

The cadmium (Cd (II)) detection sensor consists of working electrode, counter electrode and reference electrode made with thick film technology on sensitive material-based carbon electrodes (G/N/IL/SPCE) and coated with Bismuth film. Carbon (C) paste, Ag | AgCl is used as working electrode, counter electrode and reference electrode material on alumina substrate by screen printing. The working electrode was doped with Graphene (G), Nafion (N) and Ionic liquid (IL). Furthermore, Bismuth-Film (BiF) is coated with electrodeposition on the surface of the working electrode. Electrode characterization with SEM is conducted to see the morphology of sensitive materials. It showed that the particles were distributed evenly on the surface of the electrode with spherical particles. Analysis using EDS shows the element’s atomic composition is C 91.57%, N 3.48%, O 3.23%, Bi 0.01%. The performance of the cadmium sensor was tested with a potentiostat in a standard Cd solution with a concentration of 0.005 mgL-1 – 1 mgL-1 indicating an average output voltage range of 10.36 volts - 10.37 volts. This can be explained that the sensor can detect Cd (II) content properly according to performance.

Indonesia as an agricultural country has agricultural lands are quite spacious and most of the people working in this sector. However, agricultural production has not yet fulfilled domestic demand. One effort to increase agricultural production is to apply precision farming method where conducted monitoring and analysis of soil conditions prior to land management activities by using sensor technology. This paper described the development of sensor systems for measuring ion phosphate concentration as the main nutrient. The sensor employs an electrochemical amperometric measurement technique, based conductive polymer as an ion-sensitive membrane through electro-polymerization technique and electrode fabrication using thick film technology. Three configuration electrodes has been used for the sensor and working and auxiliary electrode was made by carbon while the reference electrode fabricated use silver|silver chloride. The ion phosphate sensor was characterized using a standard phosphate solution 10−6 - 10−2 M and produced current about 4 to 41 μA with 98 % linearity, and 150 seconds average of response time. In addition, signal conditioning and data acquisition as electronic circuit system which has support the sensor have been designed and fabricated.

Lanthanide up-converting luminescent nanoparticles (UCNPs) are exciting and promising materials for optical bioimaging, biosensor and theranostic due to their unique and advantageous optical and chemical properties. The UCNPs absorb low energy near-infrared (NIR) light and emit high-energy shorter wavelength photons (visible light). Their unique features allow them to overcome various problems associated with conventional imaging probes such as photostability, lack of toxicity, and to provide versatility for creating nanoplatforms with both imaging and therapeutic modalities. This paper reports synthesis and characterization of core-shell structured of NaYF4:Yb,Tm/SiO2 microspheres. The synthesis of lanthanide upconversion nanoparticles NaYF4:Yb,Tm was prepared by thermal decomposition process which involves dissolving organic precursors in high-boiling-point solvents oleic acid (OA) and octadecene (ODE). After that, the NaYF4:Yb,Tm phosphors was coated by silica via reverse microemulsion process to obtain core-shell structured NaYF4:Yb,Tm/SiO2. Scanning electron microscopy, transmission electron microscopy, specific area electron diffraction, and photoluminescence were applied to characterize these samples. The obtained core-shell structured NaYF4:Yb,Tm/SiO2 phosphors exhibit a perfect cubic morphology with narrow size distribution and smooth surface. Upon IR excitation at 980 nm, the NaYF4:Yb,Tm/SiO2 samples exhibit whitish blue upconversion (UC) luminescence, respectively. These phosphors show potential applications in the displaying on biological fields and biosensing.

Circuit Design for Sensor Detection Signal Conditioner Nitrate Content. Nitrate is one of macro nutrients very important for agriculture. The availability of nitrate in soil is limited because it is very easy to leaching by rain, therefore nitrate could be contaminated ground water by over-process of fertilizer. This process could also produce inefficiency in agriculture if it happened continuesly without pre-analysis of farm field. The answer those problems, it is need to develop the ion sensor system to measure concentrations of nitrat in soil. The system is consist of nitrate ion sensor device, signal conditioning and data acquisition circuit. The design and fabrications of signal conditioning circuit which integrated into ion nitrate sensor system and will apply for agriculture. This sensor has been used amperometric with three electrodes configuration: working, reference and auxiliarry; the ion senstive membrane has use conductive polymer. The screen printing technique has been choosen to fabricate electrodes and deposition technique for ion sensitive membrane is electropolymerization. The characterization of sensor has been conducted using nitrate standard solution with range of concentration between 1 µM–1 mM. The characterization has shown that sensor has a good response with cureent output between 2.8–4.71 µA, liniearity factor is 99.65% and time response 250 second.