Onlaor, Korakot
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Preferred name
Onlaor, Korakot
Alternative Name
Onlaor, K.
Main Affiliation
Email
korakot.on@kmitl.ac.th
16 results
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Item type:Publication, Preparation of pH Sensor Based on Extended-Gate Field-Effect Transistor with Spinel ZnCo2O4 Thin Films by Electrostatic Spray Deposition(2023-12-01); ; Electrostatic spray deposition was applied to prepare pH sensing with spinel ZnCO<inf>2</inf>O<inf>4</inf> thin films based on the measurement of extended-gate field-effect transistors (EGFET). The influence of annealing temperatures on the characteristics of the prepared films was analyzed. The structural and morphological properties of the annealed ZnCo<inf>2</inf>O<inf>4</inf> films were assessed by x-ray diffraction, x-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, and contact angle measurement. The effect of the ZnCo<inf>2</inf>O<inf>4</inf> annealing temperature on the characteristics of pH sensing for the prepared ZnCo<inf>2</inf>O<inf>4</inf> films in EGFET measurement were examined with pH buffer solutions in a pH range of 2–12 at room temperature. The sensing films annealed at 550°C demonstrated a high voltage and current sensitivity at 67.6 mV/pH and 1.033 (µA)<sup>½</sup>/pH, with linearity values of 0.9968 and 0.9991, respectively. Moreover, the annealed 550°C ZnCo<inf>2</inf>O<inf>4</inf> film exhibited low hysteresis at 4.99 mV and high retention stability. The results revealed that the pH sensing of the ZnCo<inf>2</inf>O<inf>4</inf> EGFET device showed a super-Nernstian sensitivity, which indicated the influence of the surface properties of the annealed film. Therefore, the ZnCo<inf>2</inf>O<inf>4</inf> film should be considered a potential option for the pH sensing layer in EGFET applications. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Preparation of Conductive Screen-Printing Ink for High-Performance Bendable and Wearable ECG Electrodes on Fabric Substrates(2022-12-15); ; Monitoring of vital signs is a necessary tool to diagnose the symptoms of illness. This work developed screen-printing inks for conductive nanomaterials to fabricate electrocardiogram (ECG)-compatible fabric electrodes. The contents of the polymer matrix, calcium carbonate additive filler, and conductive nanomaterials (silver nanoparticles and copper nanowires) on the resistivity of the composite inks were optimized. A facile process of screen printing was applied to fabricate the electrodes on fabric to create an efficient conductor with high stability in conduction. The fabricated electrodes exhibited flexible and bendable behavior over 0.7% bending strain for wearable components. The results showed that the fabricated electrode based on copper nanowires resistivity was 40.01 ± 1.94 k Ω/cm, and the proposed signal-to-noise ratio (SNR) was approximately 27.16 ± 9.37 dB. Therefore, these fabricated electrodes can be applied in wearable vital biosignal detection devices that perform with high sensitivity during movement, thereby providing health monitoring opportunities. Moreover, the fabricated electrodes can be used without excessive pressure or an electrolyte gel layer, thus overcoming the challenges of developing a portable device. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Selective electrochemical determination based on magnetic molecularly imprinted polymers for albumin detection(2022-06-01); ; Egg allergy is one of the most common allergies in humans. Allergenic egg protein as ovalbumin is the most abundant protein found in egg white. A selective electrode in electrochemical analysis for albumin from egg white was developed based on magnetic molecularly imprinted polymers (albumin-MMIPs) modified on a screen-printed electrode. Surface modification was applied using methyl methacrylate polymer to create surface specificity for albumin protein. The modified surface was characterized by a field-emission scanning electron microscope (FE-SEM). The average pore size was obtained by Brunauer-Emmett-Teller (BET) analysis, and the potentiostat obtained all electrochemical analysis. The albumin-MMIP electrode was selectivity with albumin, comparison with gluten, glycine, casein, and glucose. The modified electrodes present selectivity of 1.13 × 104 μAg-1ml and a limit of detection of 0.18 mg ml-1. The electrode can be applied to albumin protein detection in solution form in food industries. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Enhancing the sensitivity and selectivity of salbutamol detection using reduced graphene oxide combined with molecularly imprinted polymers (RGO/MIP)(2022-06-01); ; Klamchuen, AnnopIn this study, to enhance the selectivity and sensitivity of salbutamol detection performed by a carbon plate electrode, the electrode was modified using a novel molecularly imprinted polymer (MIP) combined with reduced graphene oxide (RGO). The RGO/MIP combination was prepared by the polymerization of methacrylic acid as a monomer using salbutamol as a template. The surface morphologies of the modified electrodes were studied using field-emission scanning electron microscopy (FE-SEM), and their performance was tested by an electrochemical technique that investigated both the cyclic voltammetry (CV) and amperometry (AMP) modes. The performance of the modified RGO/MIP electrode was compared with that of an MIP electrode, in which the RGO/MIP electrode was demonstrated to have 4.16 nA/ppm of sensitivity, more than the 0.91 nA/ppm of the MIP electrode. The limit of detection (LOD) of the RGO/MIP electrode, which was 0.83 ppm, was lower than that of the MIP electrode. Moreover, the RGO/MIP electrode’s dynamic range extended from 1 to 1000 ppm, and it exhibited consistency, repeatability, a fast response, and high selectivity for salbutamol detection. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Electrical Properties of Eggshell-Derived CaO Composited with Polyvinylpyrrolidone for Bistable Device(2022-01-01); ; - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Preparation of iron oxide (Fe2O3) nanoparticles thin film for humidity sensing device(2021-09-15); ; - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Preparation of Nanofibers of Poly (methyl methacrylate) Composited with Few-Layer-Graphene for Anticorrosion Layer(2022-12-01); ; An anticorrosion layer is a significant component that prevents the corrosion process in materials. In this work, a nanofiber of poly (methyl methacrylate) composited with few-layer-graphene was prepared as an anticorrosion layer. An electrospinning process was applied to prepare composite nanofiber on a metal substrate at various concentrations of few-layer graphene. The physical properties of the composite nanofiber were investigated with field-emission scanning electron microscope, Raman spectroscopy, and contact angle measurement. The corrosion behavior was tested in an aqueous solution of 3.5% by weight of sodium chloride. It was found that a few-layer graphene concentration of 2 wt% in polymethacrylate showed the optimum anticorrosion on aluminum sheet, as observed on a Tafel graph. Compared with the uncoated metal, the coated aluminum sheet was protected against corrosion with a protection efficiency of 99.33%. The prepared materials prevented the infiltration of water and solution ions into the metal plate. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Developing a Vital Signal Detection Electrode for Fabric Substrate Using a High-Performance Conductive Carbon-Based Ink(2025-01-01); ; Merging electrophysiology signal monitoring technology with wearable devices offers interesting future health care options. This study presented carbon-based screen-printing inks produced by mixing a graphite composite with a polymer emulsion to bind with flexible fabric substrates and tested with 10,000 bending cycles. The prepared carbon-based ink performed well for electrical conduction and vital signal response. Adding calcium carbonate resulted in a microstructure of graphite that decreased the electrical sheet resistance and resistance to 11.61 Ω/ and 0.127 Ω. The signal-to-noise ratio of the electrocardiogram (ECG) was 31.02 dB with built-in front-end powering noise filtration. Noninvasive blood pressure (NIBP) was achieved by bio-impedance measurement and showed outstanding systolic and diastolic pressure values with a correlation coefficient of 0.799, and exhibited a similar interval time to define the same precise heart rate. The ECG data from the prepared electrode were applied to the machine learning models. The Random Forest (RF) model exhibited the optimized prediction value, with an F1 score of 99.9%. Equipment made from carbon screen-printing inks showed potential for health care monitoring with no excessive pressure, dry processing, and repeatability as a flexible wearable bio-electronic device. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Preparation of surface-modified electrode of copper(ii) oxide mixed with the molecularly imprinted polymer for enhancement of melamine detection with photoelectrochemical technique(2023-05-15); ; Klamchuen, AnnopMelamine contamination in food and beverages affects short- and long-term health. In this work, enhanced sensitivity and selectivity in photoelectrochemical determination for melamine detection was achieved using copper(ii) oxide (CuO) combined with a molecularly imprinted polymer (MIP). A CuO nanomaterial was used to achieve MIP surface modification via co-precipitation synthesis. An MIP film was deposited by polymerizing the methacrylic acid monomer and a melamine template. The properties of the CuO nanomaterials, such as the surface morphology, chemical oxidation state, and crystalline structure, were characterized using field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction patterns (XRD), respectively. The diffuse reflection spectroscopy technique was applied to evaluate the optical properties of the CuO nanoparticles. The results indicated that the synthesized CuO nanomaterials had a monoclinic structure with an optical bandgap of 1.49 eV, which corresponds to absorbance in the visible light region. CPE electrodes with surface-modified CuO/MIP were measured using the photoelectrochemical techniques of cyclic voltammetry, differential pulse voltammetry (DPV), and amperometry. The modified CuO/MIP electrode for melamine detection in 7.4 pH PBS buffer solution exhibited a high sensitivity of 0.332 nA nM<sup>−1</sup>, with a linear range of 5.0-75.0 nM and a limit of detection of 2.45 nM. Moreover, real samples of various kinds of milk were applied to evaluate the sensing response of the prepared CuO/MIP electrode. The modified CuO/MIP electrodes could be reused seven times with good reproducibility and high selectivity for melamine detection. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Influence of Phase Structure of TiO2 Nanoparticles on Resistive Switching Devices(2024-01-03); ; In this work, the electrical memory properties of a bi-stable device based on the structure of aluminum/poly (9-vinyl carbazole) (PVK): TiO<inf>2</inf> NPs/indium-tin-oxide (ITO) were reported. The effects of the modified phase structural of titanium dioxide nanoparticles (TiO<inf>2</inf> NPs) on the electrical memory characteristics were determined. The TiO<inf>2</inf> NPs were annealed at different annealing temperatures. The physical properties of the annealed TiO<inf>2</inf> NPs were characterized by transmission electron microscope and X-ray diffraction, which revealed the composition and structure of the anatase and rutile phases. Current-voltage measurements showed that the bi-stable characteristics were affected by the phase structure of the TiO<inf>2</inf> NPs. The ON/OFF current ratio of the fabricated device was noted to be approximately 2.06×10<sup>5</sup> in the case of TiO<inf>2</inf> NPs annealed at 500°C. A theoretical model was used to explain the charge injection mechanisms of the device. Moreover, the temperature dependence and retention-time measurements of the device were demonstrated.