Showing papers by "Adisorn Tuantranont published in 2012"

Inkjet-printed graphene-PEDOT:PSS modified screen printed carbon electrode for biochemical sensing

Abstract: In this work, a novel method for electrode modification based on inkjet-printing of electrochemically synthesized graphene-PEDOT:PSS (GP-PEDOT:PSS) nanocomposite is reported for the first time. GP-PEDOT:PSS dispersed solution is prepared for use as an ink by one-step electrolytic exfoliation from a graphite electrode. GP-PEDOT:PSS layers are then printed on screen printed carbon electrodes (SPCEs) by a commercial inkjet material printer (Dimatrix Inc.) and their electrochemical behaviors towards three common electroactive analytes, including hydrogen peroxide (H2O2), nicotinamide adenine dinucleotide (NAD+/NADH) and ferri/ferro cyanide (Fe(CN)63−/4−) redox couples, are characterized. It is found that the oxidation signals for H2O2, NADH and K2Fe(CN)6 of PEDOT:PSS modified and GP-PEDOT:PSS modified SPCEs are ∼2–4 and ∼3–13 times higher than those of unmodified SPCE, respectively. In addition, excellent analytical features with relatively wide dynamic ranges, high sensitivities and low detection limits have been achieved. Therefore, the inkjet-printed GP-PEDOT:PSS electrode is a promising candidate for advanced electrochemical sensing applications.

Facile preparation of graphene–metal phthalocyanine hybrid material by electrolytic exfoliation

Abstract: In this article, we present a new, facile and efficient electrochemical method for the production of a stable aqueous dispersion of a graphene–metal phthalocyanine hybrid material. The material has been prepared by electrolytic exfoliation of graphite in an electrolyte containing copper phthalocyanine-3,4′,4′′,4′′′-tetrasulfonic acid tetrasodium salt (TSCuPc). Single- and few-layer graphene sheets, decorated with metal phthalocyanine molecules, are generated during the electrolysis and stably dispersed in the electrolyte with no further chemical treatment. Scanning electron/atomic force microscopic characterization shows that the TSCuPc–graphene hybrid structure has a sharp-edged particle morphology with thicknesses ranging from 2 nm to 6 nm, corresponding to 1 to 6 graphene-stacked layers and largely varied lateral dimensions from a few tens to several hundreds of nanometers. In addition, Raman/FTIR/UV-Vis spectra and X-ray diffraction reveal characteristic peaks that suggest that the TSCuPc–graphene hybrid is formed by non-covalent π–π interactions between graphene sheets and metal phthalocyanine and indicate a high quality graphene hybrid structure that can potentially be used in practical applications.

Inkjet-printed graphene-poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) modified on screen printed carbon electrode for electrochemical sensing of salbutamol

Abstract: In this work, a simple and sensitive inkjet-printed graphene-poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (GP-PEDOT:PSS) on screen printed carbon electrode (SPCE) is developed for detection of salbutamol (SAL), a prohibited drug in sport. GP-PEDOT:PSS dispersed solution is prepared for use as an ink by one-step electrolytic exfoliation from a graphite electrode. GP-PEDOT:PSS layers are then printed on SPCEs by dimatrix inkjet material printer and their electrochemical behaviors are characterized. It is found that SAL oxidation peak responses of PEDOT:PSS modified and GP-PEDOT:PSS modified SPCE electrodes are approximately 30 and 150 times higher than that of unmodified SPCE, respectively. In addition, excellent analytical features with a wide dynamic range of 500 μM, a low detection limit (3S/N) of 1.25 μM and low matrices’ interference in pharmaceutical samples have been achieved. Therefore, inkjet-printed GP-PEDOT:PSS SPCE is a promising candidate for advanced electrochemical sensing applications.

Wireless black box using MEMS accelerometer and GPS tracking for accidental monitoring of vehicles

Abstract: In this work, wireless black box using MEMS accelerometer and GPS tracking system is developed for accidental monitoring. The system consists of cooperative components of an accelerometer, microcontroller unit, GPS device and GSM module. In the event of accident, this wireless device will send mobile phone short massage indicating the position of vehicle by GPS system to family member, emergency medical service (EMS) and nearest hospital. The threshold algorithm and speed of motorcycle are used to determine fall or accident in real-time. The system is compact and easy to install under rider seat. The system has been tested in real world applications using bicycles. The test results show that it can detect linear fall, non-linear fall and normal ride with high accuracy.

Sensor pillow and bed sheet system: Unconstrained monitoring of respiration rate and posture movements during sleep

Abstract: In this paper, we have developed a low-cost sleep monitoring system for patient based on polysomnography which will be useful for patient communication with healthcare personals and/or relatives. In particular, we have presented the sensor pillow and bed sheet system that employs wireless networks based on low-cost ZigBee technology and a sensor array of force sensitive resistors (FSR) based on polymer thick film (PTF) device, for classifying and specifically verifying the respiration rate during sleep. This paper also proposes a simple motion model that explains the change of head and body pressure distribution. In addition, we can detect some physiological parameters during the sleep stages and wakefulness as well as record respiration rate as related to different physiological factors. The integration of this sensor system and wireless technology with computer software could make this healthcare monitoring system a commercial product valuable for point-of-care applications.

Enhancement of DNA hybridization under acoustic streaming with three-piezoelectric-transducer system

Abstract: Recently, we have demonstrated that DNA hybridization using acoustic streaming induced by two piezoelectric transducers provides higher DNA hybridization efficiency than the conventional method. In this work, we refine acoustic streaming system for DNA hybridization by inserting an additional piezoelectric transducer and redesigning the locations of the transducers. The Comsol® Multiphysics was used to design and simulate the velocity field generated by the piezoelectric agitation. The simulated velocity vector followed a spiral vortex flow field with an average direction outward from the center of the transducers. These vortices caused the lower signal intensity in the middle of the microarray for the two-piezoelectric disk design. On the contrary, the problem almost disappeared in the three-piezoelectric-disk system. The optimum condition for controlling the piezoelectric was obtained from the dye experiments with different activation settings for the transducers. The best setting was to activate the side disks and middle disk alternatively with 1 second activating time and 3 second non-activating time for both sets of transducers. DNA hybridization using microarrays for the malaria parasite Plasmodium falciparum from the optimized process yielded a three-fold enhancement of the signal compared to the conventional method. Moreover, a greater number of spots passed quality control in the optimized device, which could greatly improve biological interpretation of DNA hybridization data.

Nanomaterials for Sensing Applications: Introduction and Perspective

Abstract: Recent progress in synthesis and fundamental understanding of properties of nanomaterials has led to significant advancement of nanomaterial-based gas/chemical/biological sensors. This book includes a wide range of nanomaterials including nanoparticles, quantum dots, carbon nanotubes, graphene, molecularly imprinted nanostructures, nanometal structures, DNA-based structures, smart nanomaterials, nanoprobes, magnetic-based nanomaterials, phthalocyanines, and porphyrins organic molecules for various gas/chemical/biological sensing applications. Perspectives of new sensing techniques such as nanoscaled electrochemical detection, functional nanomaterial-amplified optical assay, colorimetric, fluorescence, and electrochemiluminescense are explored.

Portable optical-based electronic nose using dual-sensors array applied for volatile discrimination

Abstract: At present, electronic nose (e-nose) has become a popular tool to classify odor samples in various industries. However, most high-performance e-nose systems are in the form of desktop, thus limiting their uses in many areas of applications where analysis must be performed on site. In this work, we have developed a portable optical-based e-nose that features several advantages over traditional e-nose systems, namely changeable dual sensor arrays, plug-in low-cost LED sources and switchable air/liquid sample handling. The measurement of this e-nose is based on detection of the absorption change of Zinc-5,10,15,20-tetra-phenyl-21H,23H-porphyrin (ZnTPP) and Zinc-2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine (ZnTTBPc) thin films, as prepared by spin coating on glass substrates. By observing absorption changes of the abovementioned two types of the optically-active thin films within a narrow spectral region as produced by eight LED light sources, an array of 16 chemical sensors was created for this e-nose. We have tested this e-nose with three types of alcohols such as ethanol, methanol and isopropanol. Finally, principal component analysis (PCA) was used to analyze the data from both thin film gas sensors. The results of PCA confirm that the optical-based e-nose based on dual-sensors array successfully discriminates three types of VOCs.

Advanced nanodiamond emitter with pyramidal tip-on-pole structure for emission self-regulation

Abstract: In this paper, we report an innovative nanodiamond field emitter structure consisting of an individual pyramidal tip sitting on top of a ballast resistor “pole.” The tip-on-pole nanodiamond structures are fabricated by a new mold transfer process that is comprised of reactive-ion-etching of 3.5 μm-thick thermal oxide on Si substrate, anisotropic etching of Si, tip sharpening by thermal oxidation and chemical vapor deposition of nanodiamond. The fabricated tip-on-pole nitrogen-incorporated nanodiamond emitter exhibits a low turn-on electric field of 3.5 V/um and a very high emission current density of ∼1.7 A/cm2 at an electric field of ∼7.5 V/um. Analysis of the emission current based on Fowler–Nordheim theory indicates a current regulated regime due to the pole-structured ballast resistor with the resistance value of ∼140 kΩ. Thus, the diamond pole ballast resistor has proven to provide self-limiting of emission current that improves the total current density as well as the emission current stability of the pyramidal nanodiamond emitters. Therefore, the proposed tip-on-pole nanodiamond emitters show great promise for high current and power applications.

Real-time identification of electromyographic signals from hand movement

Abstract: In this work, we have demonstrated a novel on-line technology for real-time acquisition and identification of electromyographic (EMG) signals from hand movement. EMG signal were measured using standard surface electrodes from forearm muscles at three major points including Wrist extensor, Flexor Carpi Radialis and Wrist Flexor groups, respectively. The EMG acquisition system consists of an instrumentation amplifier, filter circuit, isolator, an amplifier with gain adjustment and a commercial embedded system called FiO board. The commercial FiO embedded system is interfaced with the computer and EMG is represented, analyzed and stored in real-time on computer by Simulink program. EMG signals are identified by RMS and SD feature extraction methods and k-mean clustering algorithm. The result revealed that both RMS and SD can be used with k-mean clustering algorithm to obtain the distinct Euclidean distance characteristic of EMG signal for each movement. The minimum Euclidean distance with RMS and SD for each hand movement uniquely occurs at a distinct Euclidean distances between real EMG data and extracted features.

Synthesis of Carbon Nanotube and Carbon Nanofiber in Nanopore of Anodic Aluminum Oxide Template by Chemical Vapor Deposition at Atmospheric Pressure

Abstract: Carbon nanotube (CNT) is one of the most attractive materials for the potential applications of nanotechnology due to its excellent mechanical, thermal, electrical and optical properties. We demonstrated the fabrication of carbon nanotube and carbon nanofiber (CNF) inside the pore and at the surface of anodic aluminum oxide (AAO) membrane by chemical vapor deposition method at atmospheric pressure. Ethanol was used as a hydrocarbon source and Co–Mo as catalyst. CNT was synthesized at different temperature. High graphitic multiwall carbon nanotube (MWCNT) was found at 750°C, while CNF was found at 800°C and above temperature analyzing by Raman spectroscopy.

Metamaterial-inspired microfluidic-based sensor for chemical discrimination

Abstract: This work proposes a metamaterial-inspired microfluidic-based chemical sensor. The sensor comprises a microwave split-ring resonator (SRR), an important building block of metamaterials, integrated with a disposable flow-channel made of a transparency film. The electromagnetic response of the sensor is observed in the presence of various analytes including glycerol, ethanol, and phosphate buffered saline. It is found that the resonance frequency in the transmission amplitude and the zero crossing in the reflection phase of the sensor are good features for discrimination of these analytes and for determining their concentrations. The developed metamaterial-inspired microfluidic-based chemical sensor has a potential for advanced chemical sensing applications.

QCM-Based DNA biosensor for Salmonella typhimurium detection

Abstract: This work demonstrated a QCM biosensor for the detection of Salmonella typhimurium using the specific DNA probe A thiol DNA probe was immobilized onto quartz surface coated with gold through self-assembly via Au-S bonding formation 6-mercapto-1-hexanol (MCH) was used as blocking reagent against non-specific DNA binding Target DNA with 94 bp (single strand) was hybridized with its probe resulted in a decrease in the resonance frequency of the QCM biosensor It was demonstrated that the QCM biosensor could recognize the target DNA sequence within 40–70 min The frequency shift signal was distinguishable along with the increase of target concentration from 01 to 10 µM

Electrochemical sensor for ascorbic acid based on graphene/CuPc/PANI nanocomposites

Abstract: In this work, the electrochemical sensor based on graphene/ copper phthalocyanine(CuPc)/ polyaniline(PANI) nanocomposite modified screen printed electrode(SPE) for detection of ascorbicacid (AA) was successfully fabricated Copper phthalocyanine was immobilized on graphene by using PANI as a matrix The nanocomposites were characterized by electrochemical techniques such as cyclic voltametry The sensor exhibited a linear range from 100 µM to 36 mM (a correlation coefficient of 09967) The sensitivity of the sensor was found to be 2292 mA M−1 cm−2 and the limit of detection was 83 µM (S/N = 3) Moreover, this sensor exhibited good electrocatalytic properties and lower the potential for the oxidation of ascorbic acid which makes it a suitable sensor for detection of ascorbic acid The performance of this sensor could provide a promising platform for the sensor or biosensor designs for AA detection

Cholesterol biosensor based on direct electron transfer of cholesterol oxidase on multi-wall carbon nanotubes

Abstract: Cholesterol biosensor based on direct electron of cholesterol oxidase(ChOx) covalently funtionalized on multi-wall carbon nanotubes(MWNTs) modified screen printed electrode(SPE) was studied. The MWNTs/ChOx/SPE has been characterized using electrochemical method including cyclic voltammetry and amperometry. Carbon Nanotubes can improve the direct electron transfer of ChOx and the electrode surface. This biosensor has good electrochemical behaviour and stability. In addition, the interferences compound in real sample such as ascorbic acid (AA), uric acid (UA), 4-acetamidophenol (AP), etc. did not cause any interference of this biosensor due to the use of a low potential from direct electron transfer of ChOx which is −0.4 V.

Health-care electronic nose to detect beer odor in breath after drinking

Abstract: Breath analysis is an interesting technique to detect several volatile organic compounds presented within the human body that can indicate the health status of individuals. For this purpose, electronic nose is a convenient device, which is based on a sensor array similar to the olfactory sense as presented in human nose. At present, electronic nose has been widely applied to classify various kinds of odors including those related to healthcare such as breath monitoring. Beer is one of the most popular alcoholic beverages which effects on health and beer odor can be detected in breathing. Beer contains various volatile organic compounds (VOCs) such as ethanol, ethyl acetate and acetaldehyde. In this work, an optical electronic nose that comprises 2 thin films acting as multiple gas sensors (Zinc-5,10,15,20-tetra-phenyl-21H-porphyrin or ZnTPP and Zinc-2,9,16,23-tetra-tert-butyl-29H, 31H-phthalocyanine or ZnTTBPc) were applied to monitor the reduction of alcohol in human breath after drinking of beer. The measurement of VOCs was investigated based on change in the optical absorption of both thin films upon interactions with the breath sample. Principal component analysis (PCA) was used as classification technique to analyze VOCs in form of fingerprint. It was found that the optical electronic nose is capable of tracking alcohol decay in exhaled breath with the passing time.

On-chip irreversible electroporation for bacterial cell membrane rupture

Abstract: In this work, the DNA preparation process for genetic analysis was developed. To rupture the cell membrane of Salmonella on a microfluidic chip, high electric field pulses were applied through gold electrode. The applied voltage was less than 10V DC voltage. Electric field pulses were short-duration in microsecond. Fluorescent spectrophotometer was employed for live/dead bacterial cells detection. The live bacterial cells were tagged by SYTO 9 green fluorescent stain. The red-fluorescent nucleic acid stain, propidium iodide was used to tag the dead cells. The highest percentage of 95% dead cells was at 7V applied voltage and 90 μs pulse duration. This result was confirmed by plate count with completely dead cell.

Industrial community odor monitoring utilizing wireless electronic nose for human health protection

Abstract: Community odor in industrial areas should be regularly monitored and controlled for human health protection. Wireless odor sensor is a new science-base approach highly promising for this application. In this work, wireless electronic nose has been developed for odor sensing by deploying commercial gas sensor arrays, microcontrollers and ZigBee wireless network. The system is applied for environment classification at various divisions in Bangpu industry near Swang Kaniwas rehabilitation center including tanning factory, dry leather area, bone factory, waste area and waste water treatment plant. Air data measured by multi-sensor arrays are delivered via ZigBee network to a database station where PCA as linear explorative technique analysis is used to obtain odor dispersion and air-quality classification. The ambient quality in Bangpu industrial park area has been successfully classified by the developed system. Thus, the wireless odor sensor approach has successfully demonstrated for industrial ambient quality monitoring, which is highly beneficial for human health protection.

Single plate electrowetting on dielectric biochip

Abstract: Electrowetting is well known method for microfluidic technology that plays a critical role in lab-on-a-chip systems by delivering chemical or biological samples. Once electrical potential is applied, the contact angels change and driving the droplet. In this report, a single-plate electrowetting on dielectric (EWOD) was fabricated and tested, containing both the control and ground square-shaped electrodes on one plate with dimension of 2 mm width and 2 mm long, fabricateded by thin film deposition methods and micromolding process. For droplet transportation, we designed electrical circuits using a microcontroller to control relays that switching voltage applied to control electrodes on and off. Interfacing RS232 with microcontroller makes the droplet transporting can be modified from personal computer by sending commands from a PC to a microcontroller.

Experimental study of digital microfluidic biochip

Abstract: Digital microfluidic biochip was fabricated with a single-plate EWOD device. The EWOD microfluidic system consists of 1.4 mm wide, 10 mm long. An enzyme and DNA was driven by moving droplet through each electrode (dimension of 2 mm width and 2 mm long) that control by digital operation. The digital microfluidic biochip has been successfully designed fabricated and tested. The fundamental fluidic operation (transporting and merging) were studied by controlling the wetting property of the droplet surface through electric potential, which can be used for lab-on-a-chip or micro total analysis system (μTAS). The tested results confirm that ionized droplet can be transported with fully controlled manner by applying voltage less than 60 V. Moreover, the droplet can be merged by applied voltage to generate digital signal for two control electrodes at the same condition.

Characterization of graphene electrode on nickel thin film for electrochemical sensing

Abstract: In this work, chemical vapor deposited (CVD) graphene on sputtered nickel thin film using acetylene as a carbon source is characterized for electrochemical sensing applications. Nickel catalyst was deposited by magnetron sputtering on SiO 2 /Si substrate. Graphene was grown under the flow of 3/24 sccm acetylene/hydrogen at a pressure of 0.4 Torr and a temperature of 700 °C for 1 minute. Characterizations by scanning/transmission electron and atomic force microscopy show that synthesized graphene film has multiple layers with very smooth surface and high degree of crystallinity. Raman spectra further confirm graphene structure with relatively high and sharp 2D peak compared to graphite. The electrochemical sensing performance of graphene electrode is evaluated for detections of potassium iodide by cyclic voltammetry. The graphene/nickel electrode exhibits highly pronounced redox peaks at 0.4 V, 0.55 V and 0.8 V while nickel electrode show no apparent redox peak. Thus, the presence of CVD graphene film greatly enhances electrochemical performance of Ni electrode.

Phthalocyanine/graphene hybrid-materials for gas sensing in bio-medical applications

Abstract: In this work the fabrication of graphene/metal phthalocyanine (MePc) hybrid-materials was investigated. MePcs are biomimetic compounds modelled after the biologically important class of porphyrins (e.g. heme-group). They are widely used in sensing applications, since they exhibit easily detectable physicochemical changes when exposed to analytes frequently found in biology such as alcohols, aldehydes and other hydrocarbons, which makes them potential candidates for bio-medical devices such as breath-analyzers. Hence, it was attempted to enhance sensing performance by introducing graphene, which offers intriguing new possibilities for MePc-based sensing materials. Hybrid-material has been produced by mixing and sonicating graphene and MePc in solution. This method lead to immobilization of MePc on graphene sheets by π-π stacking. The material has been investigated by UV/Vis spectroscopy, optical-and electron scanning microscopy (SEM). Finally, gas sensing experiments have been performed to investigate the influence of the addition of graphene on the optical and electrical sensing behaviour of MePc films. It could be shown that the effect on optical sensing capabilities is rather slight. However, upon introduction of highly conductive graphene, MePc-based materials are more readily applicable as conductometric/potentiometric gas sensors.

Integration of CNT-Based Chemical Sensors and Biosensors in Microfluidic Systems

Abstract: We describe and discuss the different components necessary for the construction of a microfluidic system including micropump, microvalve, micromixer and detection system. For the microfluidic detector, we focus on carbon nanotube (CNTs) based electrochemical sensors. The properties, structure and nomenclature of CNTs are briefly reviewed. CNT modification and the use of CNTs in conjunction with electrochemical microfluidic detection are then extensively discussed.

P2.1.3 Inkjet-printed graphene-PEDOT:PSS modified on screen printed carbon electrode for sensing applications

Abstract: In this work, a novel method for electrode modification based on inkjet-printing of electrochemically synthesized graphene-PEDOT:PSS (GP-PEDOT:PSS) nanocomposite is reported for the first time. GP-PEDOT:PSS dispersed solution is prepared for use as an ink by one-step electrolytic exfoliation from a graphite electrode. GP-PEDOT:PSS layers are then printed on screen printed carbon electrodes (SPCEs) by a commercial inkjet material printer and their electrochemical behaviors are characterized towards three most common electroactive analytes including hydrogen peroxide (H2O2), nicotinamide adenine dinucleotide (NAD/NADH) and ferri/ferro cyanide (Fe(CN)6 redox couples. It is found that the oxidation signals for H2O2, NADH and K2Fe(CN)6 of PEDOT:PSS modified and GPPEDOT:PSS modified SPCEs are ~2-4 and ~3-13 times higher than those of unmodified SPCE, respectively. In addition, excellent analytical features with relatively wide dynamic ranges, high sensitivities and low detection limits have been achieved. Therefore, the inkjet-printed GPPEDOT:PSS electrode is a promising candidate for advanced electrochemical sensing applications.

On-chip cell separation and manipulation using traveling wave dielectrophoretic force controlled by four-phase signal generator

Abstract: In this work, we present a device for cell manipulation and separation using travelling wave dielectophoretic (twDEP) force. The device consists of microchamber and 16 parallel electrode array controlled by four-phase signal. The dielectrophoretic PDMS chamber and Cr/Au parallel electrode array were fabricated by standard microfabrication techniques. The driving signals for the twDEP system are produced by a specially designed four-phase signal generator. The signal generator can be operated in a fixed or ±90° phase shift mode with varying frequency, applied voltage and shift interval. In addition, the signal conditions can be store to and retrieved from a built-in database. The twDEP system was tested with polystyrene microspheres suspension in de-ionized water and red blood cells in D-mannitol solution. Cells responded to the electric field in various mechanisms depending on the applied signals conditions. The results showed that the twDEP force occurred when the applied signals were 10 V (50 kHz–700 kHz) and 7V (30 kHz–1MHz) for 4.5 μm and 10 μm microspheres respectively. The mixed solution containing equal amount of 4.5 and 10 μm microspheres were used for separation test. Under the signal conditions for 10 μm microspheres, the microspheres were moved under twDEP force while the smaller microspheres were attached to the electrodes. Therefore, the twDEP device can successfully manipulate and separate the microspheres of different sizes, and it can be further applied for cells selection.

Design and experimental study of electrochemical detector with EWOD for chemical analysis

Abstract: In this work, we describe design and experimental studies of a electrochemical detector by using electrowetting on dielectric (EWOD) digital microfluidics microchip for chemical analysis. For the design, the electrochemical EWOD digital microfluidics system consists of T-junction EWOD microchip for merging buffer reagent and analyte droplets and three internal electrochemical detector 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 single-plate EWOD microchip has been successfully fabricated and tested to study possibility of moving (merging and transporting) droplet on the microchip. For controlling droplet, we designed electrical circuits using a microcontroller to control relays that switching applied voltage to control electrodes on and off. Interfacing RS232 with microcontroller makes the droplet merging. Merging a droplet can be modified from personal computer by sending commands from a PC to a microcontroller. The tested results show that successfully move (merging) of deionized droplets along patterned single plate EWOD device by controlling of microcontroller.