Papers by Thitima Maturos
The IoT wearable stretch sensor using 3D-Graphene foam
2015 IEEE SENSORS, 2015
In this work, we have developed flexible and wearable Stretch Sensor based on the Internet of thi... more In this work, we have developed flexible and wearable Stretch Sensor based on the Internet of thing technology. These sensors were realized using a 3D-Graphene foam amalgam with Polydimethylsiloxane (PDMS). To demonstrate the 3D-graphene foam sensors, we constructed an armband muscle measurement using such sensors and developed software based on IoT for real-time muscle expansion and stretch tracking. Wi-Fi was used to transfer data from the sensor to a cloud via web-socket based on Node.js. The data are display expansion of muscle on a website. This muscle stretch tracking is very useful in many contexts such as workout performance measuring, rehabilitation and tele-robotics application. The wearable stretch sensor is consisting of two pieces of 5 centimeters 3D-graphene foam strip and packed with clasped by conductive epoxy. For accuracy, at the end of sensor edge are coated with silver paste for better conductivity. Main CPU uses Intel Edison, which made the sensor connect to the Internet easier. In order to deploy this sensor with another application the ADXL335 was chosen as a 3-axis accelerometer for tracking of gestures or fitness tracking application. An accelerometer was attached to the down side of the Intel Edison main CPU board and including battery and analog to digital converter circuit.
Graphene digital microfluidics microchip
2017 14th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology (ECTI-CON), 2017
In this research, graphene digital microfluidics microchip was designed and fabricated by screen ... more In this research, graphene digital microfluidics microchip was designed and fabricated by screen printing. The microchip was designed with electrowetting on dielectric as digital microfluidic microchip combine with electrochemical detector on single plate substrate. For the design, the chip consist of T-junction EWOD digital microfluidics microchip for merging buffer reagent and analyze droplets and an electrochemical detector at the end of T-junction EWOD. Both parts were fabricated by screen printed technique. The EWOD microchip consists of silver paste for electrodes layers and PDMS for dielectric and TeflonÂź AF hydrophobic layers. Three electrodes of electrochemical detector consists of a graphene-carbon paste working electrode and a graphene-carbon paste counter electrode, and silver/silver chloride paste reference electrode for rapid analysis with minimal reagent consumption. In experiment, the electrochemical detector combine with EWOD microchip was tested for electrochemical analysis with concentration of the reagent that were varied with 10, 50, 100, 250, and 500 ÎŒM with cyclic voltammograms. The results showed that the system was successfully tested for rapid analysis with minimal reagent consumption of ferri/ferrocyanide (Fe(CN)63â/4â) and hydrogen peroxide (H2O2) with time was less than 20 seconds.
This study presents problems and results in fabricating microfluidic devices for biological sampl... more This study presents problems and results in fabricating microfluidic devices for biological sample manipulation at Kasetsart University, Chalermphrakiat Sakon Nakhon Province Campus. Electrodes obtained from sputtering technique are used to produce dielectrophoretic force on the devices. The electrodes were fabricated with three different current conditions. The polydimethylsiloxane (PDMS) labon-a-chip (LOC) design from a literature was considered specifically as a microfluidic device prototype. The PDMS LOCs were fabricated manually at Chalermphrakiat Sakon Nakhon Province Campus but all components were prepared and fabricated at Nanoelectronics and MEMS Laboratory, National Electronics and Computer Technology Center. The PDMS LOC was aimed to use with biological samples and different frequencies of AC electric fields. From the LOC fabrication results, the higher current in electroplating process, the coarser electrode surfaces, the finished LOC with these electrodes showed problem...
Thammasat International Journal of Science and Technology, 2011
A re-design of the sensor for measuring thermal conductivity of nanofluids is developed. The Tran... more A re-design of the sensor for measuring thermal conductivity of nanofluids is developed. The Transient Planar Source (TPS) method is used to measure the thermal conductivity of a nanofluid. This TPS sensing element consists of a heat source and a temperature sensor, where the temperature coefficient of resistance is derived from a calibration of the sensor, in a measurement of the resistance across the leads of the sensor. The TPS system (Hot Disk) consists of a 10-mm-diameter sensor head fixed into a nanofluid measurement chamber, This sensor is used to measure the thermal conductivity of Cu-H2O nanofluids with the effect of pH surfactant included. These nanofluids were prepared by a two-step method, which results in an average 100-nm particle size distribution. To improve the dispersion behavior, a surfactant at pH 9.2 is also used. The method shows good utility for measuring a thermal conductivity at a wide range of temperatures. Keywords: Nanofluids, TPS, Thermal conductivity, S...
Cells Separation by Traveling Wave Dielectrophoretic Microfluidic Devices
IFMBE Proceedings
In this work, we present a microfluidic device with a 16 parallel electrode array and microchambe... more In this work, we present a microfluidic device with a 16 parallel electrode array and microchamber for cell separation by using travelling wave dielectophoretic force. The dielectrophoretic PDMS chamber was fabricated using standard microfabrication techniques. The Cr/Au parallel electrode array of 100 ”m wide and 300 nm thick was patterned on a glass slide by sputtering through microshadow mask. In order to test twDEP devices, two different size of polystyrene microspheres suspension in deionized water were used as the tested cells. Each type of polystyrene was tested in both the separated and mixed solution. Cells response to the electric field in various mechanisms depending on the applied voltage and frequency of AC signals. For 4.5 ”m polystyrene, cells were forced to locate in the center between electrode array and move along the channel and the traveling wave dielectrophoresis occur, when the applied voltage was 10 V and the frequency of the applied signals is in the range of 50 kHz-700 kHz. For 10 ”m polystyrene the twDEP occurs when the applied voltage was 7 V and frequency was in the range 30 kHz-1MHz. For the mixed solution containing equal amount of 4.5 and 10 ”m microspheres, the big microspheres were moved under twDEP force when the applied voltage was 7 V and the frequency was in the range 25 kHz-1MHz while the small microspheres were attached to the electrodes. Therefore, the twDEP device can separate the microspheres with different sizes and it can be further applied for cells separation and manipulation.
BioChip Journal, 2011
The ability for low reagent consumption and minimum waste production in a miniaturised system has... more The ability for low reagent consumption and minimum waste production in a miniaturised system has generated great interest in the green chemistry field. Herein, a microfluidic system for calcium assays using the arsenazo III method has been developed. The reaction between arsenazo III and calcium to form a blue-purple coloured complex is measured by an embedded miniature fibre optic spectrometer through absorbance increments at 650 nm. A linear range was obtained from 0.2 to 3 mg dL-1 with a detection limit of 0.138 mg dL-1 (S/N=3). The method exhibited good reproducibility based on low and high calcium tests with control serums, the within-run coefficient of variation (CVs) (4.10% and 3.91%), and the run-to-run CV (4.6%) were obtained. The carry-over effect of the method was also 1.98%, which is acceptable for the current system. When compared to a conventional spectrophotometric method, this portable, microfluidic method correlated highly when evaluating serum samples (r 2 =0.985; n=15). This similarity suggests that our proposed system could be used for determining the amount of calcium in serum samples.
Biosensors and Bioelectronics, 2010
This work reports a new cholesterol detection scheme using functionalized carbon nanotube (CNT) e... more This work reports a new cholesterol detection scheme using functionalized carbon nanotube (CNT) electrode in a polydimethylsiloxane/glass based flow injection microfluidic chip. CNTs working, silver reference and platinum counter electrode layers were fabricated on the chip by sputtering and low temperature chemical vapor deposition methods. Cholesterol oxidase prepared in polyvinyl alcohol solution was immobilized on CNTs by in-channel flow technique. Cholesterol analysis based on flow injection chronoamperometric measurement was performed in 150-m-wide and 150-m-deep microchannels. Fast and sensitive real-time detection was achieved with high throughput of more than 60 samples per hour and small sample volume of 15 l. The cholesterol sensor had a linear detection range between 50 and 400 mg/dl. In addition, low cross-sensitivities toward glucose, ascorbic acid, acetaminophen and uric acid were confirmed. The proposed system is promising for clinical diagnostics of cholesterol with high speed real-time detection capability, very low sample consumption, high sensitivity, low interference and good stability.
Design, Fabrication, Experimental Study, and Test Electrochemical Detector with EWOD for Chemical Analysis
IFMBE Proceedings, 2014
In this research, an electrochemical detector with electrowetting on dielectric (EWOD) digital mi... more In this research, an electrochemical detector with electrowetting on dielectric (EWOD) digital microfluidic biochip is designed, fabricated, and experimental studied for chemical analysis. For the design, the microchip consists of T-junction EWOD microchip for merging buffer reagent and analyte droplets and three internal electrochemical detectors at the end of T-junction. Three electrodes consist of Au working, Au reference, and Au auxiliary for rapid chemical analysis with minimal reagent consumption. In experiment, the electrochemical with EWOD microchip is fabricated by thin film deposition and tested to study possibility of moving (merging and transporting) droplet on the microchip by digital operation.
Preferentially oriented Fe-doped CaCu3Ti4O12 films with high dielectric constant and low dielectric loss deposited on LaAlO3 and NdGaO3 substrates
Applied Surface Science
Low Cost and Disposable Electrowetting-on-Dielectric Lab on a Chip with an Integrated Electrochemical Detector Fabricated by Screen Printing Process
IEEE Sensors Journal
Electrowetting-on-dielectric chip with integrated screen-printed electrochemical sensor for rapid chemical analysis
Materials Science and Engineering: B
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Papers by Thitima Maturos