Ruthenium oxide,which fabricated by radio frequency sputtering is used as the sensitive membrane,which shows that the pH sensitivity is very high and has a linear response in different buffer solutions.The pH electrod...Ruthenium oxide,which fabricated by radio frequency sputtering is used as the sensitive membrane,which shows that the pH sensitivity is very high and has a linear response in different buffer solutions.The pH electrode,which applies the structure of separative structure EGFET (Extended Gate Field Effect Transistor) insteads of the conventional gate ISFET (Ion Sensitive Field Effect Transistor) for reducing the cost of the fabrication and measurement.Unfortunately,the performance of the pH sensor was falsified by the drift and hysteresis.In addition,the total response is composed of the intrinsic response and drift,and the hysteresis effect combines the slow response with drift.Consequently,we would also investigate the drift in the buffer solutions and hysteresis effect in the different paths.In this way,the more accurate sensing properties are obtained by the RuO_x pH electrode.展开更多
We use the extended gate field effect transistor (EGFET)as the structure of the chlorine ion sensor,and the chlorine ion ionophores (ETH9033 and TDDMAC1)are incorporated into solvent polymeric membrane (PVC/DOS),then ...We use the extended gate field effect transistor (EGFET)as the structure of the chlorine ion sensor,and the chlorine ion ionophores (ETH9033 and TDDMAC1)are incorporated into solvent polymeric membrane (PVC/DOS),then the chlorine ion selective membrane is formed on the sensing window,and the fabrication of the EGFET chlorine ion sensing device is completed.The surface potential on the sensing membrane of the EGFET chlorine ion sensing device will be changed in the different chlorine ion concentration solutions,then changes further gate voltage and drain current to detect chlorine ion concentration.We will study non-ideal effects such as temperature,hysteresis and drift effects for the EGFET chlorine ion sensing device in this paper,these researches will help us to improve the sensing characteristics of the EGFET chlorine ion sensing device.展开更多
The nano-titanium dioxide (nano-TiO_2) sensing membrane,fabricated by sol-gel technology,was used as the pH-sensing layer of the extended gate field effect transistor (EGFET) device.The objective of this research is t...The nano-titanium dioxide (nano-TiO_2) sensing membrane,fabricated by sol-gel technology,was used as the pH-sensing layer of the extended gate field effect transistor (EGFET) device.The objective of this research is the preparation of titanium dioxide materials by sol-gel method using Ti(OBu)_4 as the precursor.In this study,we fabricated a nano-titanium dioxide sensing layer on the ITO glass by dip coating.In order to examine the sensitivity of the nano-TiO_2 films applied to the EGFET devices,we adopted the ITO glass as substrate,and measured theⅠ_(DS)-Ⅴ_G curves of the nano-titanium dioxide separative structure EGFET device in the pH buffer solutions that have different pH values by the Keithley 236 Instrument.By the experimental results,we can obtain the pH sensitivities of the EGFET with nano-TiO_2 sensing membrane prepared by sol-gel method,which is 59.86mV/pH from pH 1 to pH 9.展开更多
We use the carbon nanotube (CNT) as the material of the pH sensing layer of the separative structure for the extended gate H^+-ion sensitive field effect transistor (EGFET) device.The CNT paste was prepared with CNT p...We use the carbon nanotube (CNT) as the material of the pH sensing layer of the separative structure for the extended gate H^+-ion sensitive field effect transistor (EGFET) device.The CNT paste was prepared with CNT powder,Ag powder,silicagel,the di-n-butyl phthalate and the toluene solvents by appropriate ratio,then immobilized on the silicon substrate to form the carbon nanotube sensing layer.We measured theⅠ_(DS)-Ⅴ_G curves of the carbon nanotube separative structure EGFET device in the different pH buffer solutions by the Keithley 236Ⅰ-Ⅴmeasurement system.According to the experimental results,we can obtain the pH sensitivities of the carbon nanotube separative structure EGFET device,which is 62.54mV/pH from pH1 to pH13.展开更多
In this study,the multi-sensing system based on the tin oxide pH electrode for the ion-determination was presented. With the advantages of the real-time supervisory control apparatus,the measured values could be displ...In this study,the multi-sensing system based on the tin oxide pH electrode for the ion-determination was presented. With the advantages of the real-time supervisory control apparatus,the measured values could be displayed on the liquid crystal display (LCD) immediately.In this study,the basic sensor was the tin oxide pH electrode,which was fabricated by radio frequency (r.f.) sputtering system on the indium tin oxide (ITO)/glass substrate.Moreover,the major blocks of the system consist of the tin oxide electrode-based ion selective electrodes (ISEs),an analog front-ended readout circuit,a microcontroller with built-in analog to digital (A/D) converter.In addition,by the embedded system design,the measurement results can be transmitted to a portable system or computer through the Universal Serial Bus (USB) and Universal Asynchronous Receiver Transmitter (UART) interface immediately.According to the experimental results,the multi-sensing system has high performance and reliability for pH,K^+,and Na^+ detection.展开更多
We study the extended gate ion sensitive structure,and deposit the titanium oxide (TiO_2) thin film on p-type (100) silicon substrate.The device of the hydrogen ion sensing structure is TiO_2/Si-substrate,and a commer...We study the extended gate ion sensitive structure,and deposit the titanium oxide (TiO_2) thin film on p-type (100) silicon substrate.The device of the hydrogen ion sensing structure is TiO_2/Si-substrate,and a commercial device of the metal oxide semiconductor field effect transistor (MOSFET) is connected to the separative sensing device.The sensitivity and linearity are measured under different work pressures.When the mixed ratio of Ar/O_2 is 80 ml·min^(-1)/20 ml·min^(-1),the work pressure is 4 Pa,the sputtering power is 150 W,and the sputtering time is two hours,the better sensing properties of the sensitivity and linearity are 36.49 mV/pH and 0.99654,respectively.However,some instruments are analyzed the surface of TiO_2 membrane,such as X-ray diffraction (XRD) and Auger Electron Spectrometer (AES).The characteristics of TiO_2 thin film can be demonstrated.展开更多
An amperometric glucose biosensor based on a tin oxide (SnO_2) electrode has been developed.The SnO_2 electrode is prepared by depositing the SnO_2 thin film onto a carbon electrode.To fabricate the SnO_2 amperometric...An amperometric glucose biosensor based on a tin oxide (SnO_2) electrode has been developed.The SnO_2 electrode is prepared by depositing the SnO_2 thin film onto a carbon electrode.To fabricate the SnO_2 amperometric glucose biosensor,the glucose oxidase and electron transfer mediator (ferrocenecarboxylic acid,FcA) are coimmobilized on the SnO_2 electrode using polyacrylamide.The detection range is up to glucose concentration of 520mg/dl as the applied potential is set at 300mV. Moreover,the most merit for the SnO_2 electrode as the base electrode of the SnO_2 amperometric glucose biosensor is that it can be operated at 150mV constant applied potential.The interference reduction,detection range,sensitivity and linearity are improved as the SnO_2 thin film is deposited onto a carbon electrode.Furthermore,due to the low cost substrate and simple fabrication characteristics,a disposable amperometric glucose biosensor based on the SnO_2 electrode has been realized in this study.展开更多
An impedance type humidity sensor based on the polyacrylic emulsion containing magnesium chloride (MgCl_2) without chemical modification was investigated.The impedances of the sensor were measured from various relati...An impedance type humidity sensor based on the polyacrylic emulsion containing magnesium chloride (MgCl_2) without chemical modification was investigated.The impedances of the sensor were measured from various relative humidity in the frequency range between 0.1kHz and 100 kHz.The sensor has a good sensitivity from 60%RH to 90%RH.According to the experimental results,the response time is about 240 seconds in the adsorption process and 310 seconds in the desorption process.展开更多
Drift phenomenon has been known as the drawback of sensors and causes inaccuracy on the long-term measurement. In general,there are two methods to reduce the drift problem.One is to tune the parameters of the fabricat...Drift phenomenon has been known as the drawback of sensors and causes inaccuracy on the long-term measurement. In general,there are two methods to reduce the drift problem.One is to tune the parameters of the fabrication process to improve the properties of the front-ended device.Another is to compensate the drift phenomenon by adding extra drift compensation circuit or software in the back-ended readout circuit.In this study,a drift calibration method for the potentiometric sensor was presented and the drift calibration method was performed by using the circuit.According to experimental results,the drift phenomenon of the SnO_2 pH electrode was reduced by the drift calibration device.展开更多
The advantages of the extended gate field effect transistor (EGFET) compared with the ion sensitive field effect transistor (ISFET) are easy package,easy preservation,insensitive light effect,and better stability.Al...The advantages of the extended gate field effect transistor (EGFET) compared with the ion sensitive field effect transistor (ISFET) are easy package,easy preservation,insensitive light effect,and better stability.Although EGFET has above advantages,there are still some non-ideal effects such as drift etc..The drift behavior exists during the measurement process and results in the variation of the output voltage with time.We can obtain the drift value by immersing EGFET into the pH solution for 12 hours and measure the rate of the output voltage versus time after S hours.This study analyzes the sensitivity, stability,and drift effect of the EGFET based on the structure of the ruthenium oxide/silicon (RuO_x/Si) wafer for measuring the potassium ion.The fabrication of the potassium ion sensor can be widely employed in medical detection.展开更多
The extended gate field effect transistor (EGFET)has many advantages such as the fabrication is easy,low cost, easy to operate etc.The EGFET was applied to biosensor in recent years.In this study,the tin oxide (SnO_2)...The extended gate field effect transistor (EGFET)has many advantages such as the fabrication is easy,low cost, easy to operate etc.The EGFET was applied to biosensor in recent years.In this study,the tin oxide (SnO_2)pH sensitive membrane was deposited on ITO glass,when the surface voltage which pH membrane changes,the gate voltage and current channel of MOSFET will change immediately to detect concentration of the glucose sensor.In this study we have devoted to research about the calibration of the circuit measurement for the glucose sensor,and study the calibration system of the drift and hysteresis.展开更多
The structure of the extended gate ion sensitive field effect transistor (EGISFET) is similar to the structure of the ion sensitive field effect transistor (ISFET).Moreover,the non-ideal effect of EGISFET is the mai...The structure of the extended gate ion sensitive field effect transistor (EGISFET) is similar to the structure of the ion sensitive field effect transistor (ISFET).Moreover,the non-ideal effect of EGISFET is the main impediment to development of commercial processes for sensitive devices.It is necessary to promote the stability and reliability of the devices by employing calibration circuits and the better fabrication conditions.The temporal drift exists in the entire measurement experiment. Furthermore,in this study we can reduce the temporal drift effect which influences the stability of the TiN sensitive electrode with the differential front-end offset circuit.The measurement system combines with shifting circuit,differential and instrument amplifiers.We employ the calibration circuit to compare with the variations of the output voltage,and expectably improve the stability and reliability of the TiN sensitive electrode by the novel calibration circuit.展开更多
Enzyme was immobilized on an ammonium ion-selective electrode by different methods.An ion-selective electrode is not completely ion-specific,and interfering ions react with the ion-selective electrode membrane,alterin...Enzyme was immobilized on an ammonium ion-selective electrode by different methods.An ion-selective electrode is not completely ion-specific,and interfering ions react with the ion-selective electrode membrane,altering the measured potential.Therefore,the characteristics of the effect of other ions on ammonium ion-selective electrode-based urea biosensors are considered.Based on the experimental results,the urea biosensor based on entrapment had a high response voltage of around 189 mV and fast response time of around 16 sec.Moreover,selectivity of the urea biosensor in different interfering ions was considered to elucidate the characteristics of ammonium ion-selective electrode-based biosensors.展开更多
Continuous intra-arterial blood gas monitoring is used clinically in hospital and intensive care unit settings.The blood gas can be detected by the colormetric indicators which are sealed in the silicone membrane.The ...Continuous intra-arterial blood gas monitoring is used clinically in hospital and intensive care unit settings.The blood gas can be detected by the colormetric indicators which are sealed in the silicone membrane.The glass tubing of the sensor should be as thin as possible since it affects response time and the bicarbonate buffer shifts the sensitivity of the sensor. In this paper,the sensitivity shifts by the bicarbonate buffer was researched.When carbon dioxide diffuses into the indicator, the carbon acid is produced and the bicarbonate buffer is used to control internal acidity.Because the sensitivity of the pCO_2 sensor is increased by controlling the concentration of the bicarbonate buffer,the bicarbonate buffer is used to obtain the optimum resolution in this investigation.Moreover,the different concentrations of the bicarbonate buffer for blood gas measurements are discussed in detail.展开更多
In this paper,the pCO_2 sensitive electrode was studied for continuous measurement.The solid electrolyte membrane and gas-permeable membrane were coated on the surface of the pH sensitive electrode which was fabricate...In this paper,the pCO_2 sensitive electrode was studied for continuous measurement.The solid electrolyte membrane and gas-permeable membrane were coated on the surface of the pH sensitive electrode which was fabricated based on the SnO_2/ITO glass substrate.According to the experimental results,the pCO_2 sensitive electrode shows the sensitivity of about 35 mV/decade in detection range between 0.1 mmol/L and 50 mmol/L.Moreover,the investigated sensing structure exhibits the convenient and pragmatic properties of the pCO_2 measurement.In summary,the advantages of the pCO_2 sensitive electrode are low-cost and disposable based on the separative structure.展开更多
In this study,tin oxide sensing membrane was derived by sol-gel method and was coated onto indium tin oxide (ITO) glass substrate by spin-coating technique to fabricate a pH sensing electrode.Besides,the morphology o...In this study,tin oxide sensing membrane was derived by sol-gel method and was coated onto indium tin oxide (ITO) glass substrate by spin-coating technique to fabricate a pH sensing electrode.Besides,the morphology of the tin oxide membrane has been discussed through the instrumental analysis.Furthermore,the sensing characteristics of the pH electrode was measured by commercial instrumental amplifier as the readout circuit.Owing to the sol-gel method has many advantages such as easy fabrication of gel solution,ability to dope other materials without any expensive fabricating equipment.Hence,it is suitable for the mass production of a disposable sensor.展开更多
The polypyrrole is the high conductive polymer which was coated onto indium tin oxide (ITO) glass substrate by electroplated technique to fabricate a miniaturized reference electrode.Besides,the morphology of the ITO...The polypyrrole is the high conductive polymer which was coated onto indium tin oxide (ITO) glass substrate by electroplated technique to fabricate a miniaturized reference electrode.Besides,the morphology of the ITO glass reference electrode electroplated with pyrrole has been studied through the instrumental analysis utilizing cyclic voltammetry (CV). Furthermore,the sensing characteristics of the reference electrode have been measured by using commercial instrumental amplifier as the readout circuit.Using the high conductive polymer as miniaturized reference electrode has many advantages such as easy fabrication of coating polymer,without any expensive fabricating equipment,easy carry by the miniaturized technique.Hence,it is suitable for the reference electrode production.展开更多
This study reveals the successful design of the data acquisition system for pH sensors.The data acquisition system includes an instrumentation amplifier,a low pass filter and a calculation program.The instrumentation ...This study reveals the successful design of the data acquisition system for pH sensors.The data acquisition system includes an instrumentation amplifier,a low pass filter and a calculation program.The instrumentation amplifier used as the readout circuit has many advantages,including high input impedance,high gain,low output impedance,high CMRR and high bandwidth.The low pass filter is employed to cancel the circuit noise.The calculation program uses the two-point calibration method to calculate the sample concentration.Furthermore,this study employs Boolean function to cancel error signals.As indicated by experimental results,the readout circuit obtains the sensing signal and the calculation program calculates the pH value.Hence,this study successfully fabricates an effective data acquisition system for pH sensors.展开更多
An extended-gate field effect transistor (EGFET)of SnO_2/ITO glass was applied to manufacture the vitamin C sensor.Therefore,we immobilized the ascorbate oxidase with 3-glycidoxypropyltrimethoxysilane (GPTS)method to ...An extended-gate field effect transistor (EGFET)of SnO_2/ITO glass was applied to manufacture the vitamin C sensor.Therefore,we immobilized the ascorbate oxidase with 3-glycidoxypropyltrimethoxysilane (GPTS)method to measure the different concentrations of the vitamin C solution in an optimum measurement environment.In order to find the best measurement conditions of the biosensor,we studied the vitamin C sensor in different pH values of the phosphate buffer solution (PBS).Additionally,we used experimental results to discuss the response time and response voltage to compare vitamin C with orange juice for the vitamin C sensor.展开更多
The application of Bluetooth on the pH sensor was accomplished.Based on the experimental results,Bluetooth technology was used to measure pH values without limiting the distance.Moreover,Biuetooth technology provides ...The application of Bluetooth on the pH sensor was accomplished.Based on the experimental results,Bluetooth technology was used to measure pH values without limiting the distance.Moreover,Biuetooth technology provides low power, low cost and small volume,therefore,it can increase the practicability of the system.In this investigation,the pH value was detected by the SnO_2/ITO glass-based pH sensor.During the signal progress,the detected signal was transferred to the microchip PIC18.After that,the microchip was able to communicate with PC by the Bluetooth.Moreover,the microchip can diagnose the sensing signal and sends the warning signal by alert function.In addition,the part of PC has the ability to record the information,builds the database for analyzing the pH values,and provides a better long-distance monitoring system.展开更多
文摘Ruthenium oxide,which fabricated by radio frequency sputtering is used as the sensitive membrane,which shows that the pH sensitivity is very high and has a linear response in different buffer solutions.The pH electrode,which applies the structure of separative structure EGFET (Extended Gate Field Effect Transistor) insteads of the conventional gate ISFET (Ion Sensitive Field Effect Transistor) for reducing the cost of the fabrication and measurement.Unfortunately,the performance of the pH sensor was falsified by the drift and hysteresis.In addition,the total response is composed of the intrinsic response and drift,and the hysteresis effect combines the slow response with drift.Consequently,we would also investigate the drift in the buffer solutions and hysteresis effect in the different paths.In this way,the more accurate sensing properties are obtained by the RuO_x pH electrode.
文摘We use the extended gate field effect transistor (EGFET)as the structure of the chlorine ion sensor,and the chlorine ion ionophores (ETH9033 and TDDMAC1)are incorporated into solvent polymeric membrane (PVC/DOS),then the chlorine ion selective membrane is formed on the sensing window,and the fabrication of the EGFET chlorine ion sensing device is completed.The surface potential on the sensing membrane of the EGFET chlorine ion sensing device will be changed in the different chlorine ion concentration solutions,then changes further gate voltage and drain current to detect chlorine ion concentration.We will study non-ideal effects such as temperature,hysteresis and drift effects for the EGFET chlorine ion sensing device in this paper,these researches will help us to improve the sensing characteristics of the EGFET chlorine ion sensing device.
文摘The nano-titanium dioxide (nano-TiO_2) sensing membrane,fabricated by sol-gel technology,was used as the pH-sensing layer of the extended gate field effect transistor (EGFET) device.The objective of this research is the preparation of titanium dioxide materials by sol-gel method using Ti(OBu)_4 as the precursor.In this study,we fabricated a nano-titanium dioxide sensing layer on the ITO glass by dip coating.In order to examine the sensitivity of the nano-TiO_2 films applied to the EGFET devices,we adopted the ITO glass as substrate,and measured theⅠ_(DS)-Ⅴ_G curves of the nano-titanium dioxide separative structure EGFET device in the pH buffer solutions that have different pH values by the Keithley 236 Instrument.By the experimental results,we can obtain the pH sensitivities of the EGFET with nano-TiO_2 sensing membrane prepared by sol-gel method,which is 59.86mV/pH from pH 1 to pH 9.
文摘We use the carbon nanotube (CNT) as the material of the pH sensing layer of the separative structure for the extended gate H^+-ion sensitive field effect transistor (EGFET) device.The CNT paste was prepared with CNT powder,Ag powder,silicagel,the di-n-butyl phthalate and the toluene solvents by appropriate ratio,then immobilized on the silicon substrate to form the carbon nanotube sensing layer.We measured theⅠ_(DS)-Ⅴ_G curves of the carbon nanotube separative structure EGFET device in the different pH buffer solutions by the Keithley 236Ⅰ-Ⅴmeasurement system.According to the experimental results,we can obtain the pH sensitivities of the carbon nanotube separative structure EGFET device,which is 62.54mV/pH from pH1 to pH13.
文摘In this study,the multi-sensing system based on the tin oxide pH electrode for the ion-determination was presented. With the advantages of the real-time supervisory control apparatus,the measured values could be displayed on the liquid crystal display (LCD) immediately.In this study,the basic sensor was the tin oxide pH electrode,which was fabricated by radio frequency (r.f.) sputtering system on the indium tin oxide (ITO)/glass substrate.Moreover,the major blocks of the system consist of the tin oxide electrode-based ion selective electrodes (ISEs),an analog front-ended readout circuit,a microcontroller with built-in analog to digital (A/D) converter.In addition,by the embedded system design,the measurement results can be transmitted to a portable system or computer through the Universal Serial Bus (USB) and Universal Asynchronous Receiver Transmitter (UART) interface immediately.According to the experimental results,the multi-sensing system has high performance and reliability for pH,K^+,and Na^+ detection.
文摘We study the extended gate ion sensitive structure,and deposit the titanium oxide (TiO_2) thin film on p-type (100) silicon substrate.The device of the hydrogen ion sensing structure is TiO_2/Si-substrate,and a commercial device of the metal oxide semiconductor field effect transistor (MOSFET) is connected to the separative sensing device.The sensitivity and linearity are measured under different work pressures.When the mixed ratio of Ar/O_2 is 80 ml·min^(-1)/20 ml·min^(-1),the work pressure is 4 Pa,the sputtering power is 150 W,and the sputtering time is two hours,the better sensing properties of the sensitivity and linearity are 36.49 mV/pH and 0.99654,respectively.However,some instruments are analyzed the surface of TiO_2 membrane,such as X-ray diffraction (XRD) and Auger Electron Spectrometer (AES).The characteristics of TiO_2 thin film can be demonstrated.
文摘An amperometric glucose biosensor based on a tin oxide (SnO_2) electrode has been developed.The SnO_2 electrode is prepared by depositing the SnO_2 thin film onto a carbon electrode.To fabricate the SnO_2 amperometric glucose biosensor,the glucose oxidase and electron transfer mediator (ferrocenecarboxylic acid,FcA) are coimmobilized on the SnO_2 electrode using polyacrylamide.The detection range is up to glucose concentration of 520mg/dl as the applied potential is set at 300mV. Moreover,the most merit for the SnO_2 electrode as the base electrode of the SnO_2 amperometric glucose biosensor is that it can be operated at 150mV constant applied potential.The interference reduction,detection range,sensitivity and linearity are improved as the SnO_2 thin film is deposited onto a carbon electrode.Furthermore,due to the low cost substrate and simple fabrication characteristics,a disposable amperometric glucose biosensor based on the SnO_2 electrode has been realized in this study.
文摘An impedance type humidity sensor based on the polyacrylic emulsion containing magnesium chloride (MgCl_2) without chemical modification was investigated.The impedances of the sensor were measured from various relative humidity in the frequency range between 0.1kHz and 100 kHz.The sensor has a good sensitivity from 60%RH to 90%RH.According to the experimental results,the response time is about 240 seconds in the adsorption process and 310 seconds in the desorption process.
文摘Drift phenomenon has been known as the drawback of sensors and causes inaccuracy on the long-term measurement. In general,there are two methods to reduce the drift problem.One is to tune the parameters of the fabrication process to improve the properties of the front-ended device.Another is to compensate the drift phenomenon by adding extra drift compensation circuit or software in the back-ended readout circuit.In this study,a drift calibration method for the potentiometric sensor was presented and the drift calibration method was performed by using the circuit.According to experimental results,the drift phenomenon of the SnO_2 pH electrode was reduced by the drift calibration device.
文摘The advantages of the extended gate field effect transistor (EGFET) compared with the ion sensitive field effect transistor (ISFET) are easy package,easy preservation,insensitive light effect,and better stability.Although EGFET has above advantages,there are still some non-ideal effects such as drift etc..The drift behavior exists during the measurement process and results in the variation of the output voltage with time.We can obtain the drift value by immersing EGFET into the pH solution for 12 hours and measure the rate of the output voltage versus time after S hours.This study analyzes the sensitivity, stability,and drift effect of the EGFET based on the structure of the ruthenium oxide/silicon (RuO_x/Si) wafer for measuring the potassium ion.The fabrication of the potassium ion sensor can be widely employed in medical detection.
文摘The extended gate field effect transistor (EGFET)has many advantages such as the fabrication is easy,low cost, easy to operate etc.The EGFET was applied to biosensor in recent years.In this study,the tin oxide (SnO_2)pH sensitive membrane was deposited on ITO glass,when the surface voltage which pH membrane changes,the gate voltage and current channel of MOSFET will change immediately to detect concentration of the glucose sensor.In this study we have devoted to research about the calibration of the circuit measurement for the glucose sensor,and study the calibration system of the drift and hysteresis.
文摘The structure of the extended gate ion sensitive field effect transistor (EGISFET) is similar to the structure of the ion sensitive field effect transistor (ISFET).Moreover,the non-ideal effect of EGISFET is the main impediment to development of commercial processes for sensitive devices.It is necessary to promote the stability and reliability of the devices by employing calibration circuits and the better fabrication conditions.The temporal drift exists in the entire measurement experiment. Furthermore,in this study we can reduce the temporal drift effect which influences the stability of the TiN sensitive electrode with the differential front-end offset circuit.The measurement system combines with shifting circuit,differential and instrument amplifiers.We employ the calibration circuit to compare with the variations of the output voltage,and expectably improve the stability and reliability of the TiN sensitive electrode by the novel calibration circuit.
文摘Enzyme was immobilized on an ammonium ion-selective electrode by different methods.An ion-selective electrode is not completely ion-specific,and interfering ions react with the ion-selective electrode membrane,altering the measured potential.Therefore,the characteristics of the effect of other ions on ammonium ion-selective electrode-based urea biosensors are considered.Based on the experimental results,the urea biosensor based on entrapment had a high response voltage of around 189 mV and fast response time of around 16 sec.Moreover,selectivity of the urea biosensor in different interfering ions was considered to elucidate the characteristics of ammonium ion-selective electrode-based biosensors.
文摘Continuous intra-arterial blood gas monitoring is used clinically in hospital and intensive care unit settings.The blood gas can be detected by the colormetric indicators which are sealed in the silicone membrane.The glass tubing of the sensor should be as thin as possible since it affects response time and the bicarbonate buffer shifts the sensitivity of the sensor. In this paper,the sensitivity shifts by the bicarbonate buffer was researched.When carbon dioxide diffuses into the indicator, the carbon acid is produced and the bicarbonate buffer is used to control internal acidity.Because the sensitivity of the pCO_2 sensor is increased by controlling the concentration of the bicarbonate buffer,the bicarbonate buffer is used to obtain the optimum resolution in this investigation.Moreover,the different concentrations of the bicarbonate buffer for blood gas measurements are discussed in detail.
文摘In this paper,the pCO_2 sensitive electrode was studied for continuous measurement.The solid electrolyte membrane and gas-permeable membrane were coated on the surface of the pH sensitive electrode which was fabricated based on the SnO_2/ITO glass substrate.According to the experimental results,the pCO_2 sensitive electrode shows the sensitivity of about 35 mV/decade in detection range between 0.1 mmol/L and 50 mmol/L.Moreover,the investigated sensing structure exhibits the convenient and pragmatic properties of the pCO_2 measurement.In summary,the advantages of the pCO_2 sensitive electrode are low-cost and disposable based on the separative structure.
文摘In this study,tin oxide sensing membrane was derived by sol-gel method and was coated onto indium tin oxide (ITO) glass substrate by spin-coating technique to fabricate a pH sensing electrode.Besides,the morphology of the tin oxide membrane has been discussed through the instrumental analysis.Furthermore,the sensing characteristics of the pH electrode was measured by commercial instrumental amplifier as the readout circuit.Owing to the sol-gel method has many advantages such as easy fabrication of gel solution,ability to dope other materials without any expensive fabricating equipment.Hence,it is suitable for the mass production of a disposable sensor.
文摘The polypyrrole is the high conductive polymer which was coated onto indium tin oxide (ITO) glass substrate by electroplated technique to fabricate a miniaturized reference electrode.Besides,the morphology of the ITO glass reference electrode electroplated with pyrrole has been studied through the instrumental analysis utilizing cyclic voltammetry (CV). Furthermore,the sensing characteristics of the reference electrode have been measured by using commercial instrumental amplifier as the readout circuit.Using the high conductive polymer as miniaturized reference electrode has many advantages such as easy fabrication of coating polymer,without any expensive fabricating equipment,easy carry by the miniaturized technique.Hence,it is suitable for the reference electrode production.
文摘This study reveals the successful design of the data acquisition system for pH sensors.The data acquisition system includes an instrumentation amplifier,a low pass filter and a calculation program.The instrumentation amplifier used as the readout circuit has many advantages,including high input impedance,high gain,low output impedance,high CMRR and high bandwidth.The low pass filter is employed to cancel the circuit noise.The calculation program uses the two-point calibration method to calculate the sample concentration.Furthermore,this study employs Boolean function to cancel error signals.As indicated by experimental results,the readout circuit obtains the sensing signal and the calculation program calculates the pH value.Hence,this study successfully fabricates an effective data acquisition system for pH sensors.
文摘An extended-gate field effect transistor (EGFET)of SnO_2/ITO glass was applied to manufacture the vitamin C sensor.Therefore,we immobilized the ascorbate oxidase with 3-glycidoxypropyltrimethoxysilane (GPTS)method to measure the different concentrations of the vitamin C solution in an optimum measurement environment.In order to find the best measurement conditions of the biosensor,we studied the vitamin C sensor in different pH values of the phosphate buffer solution (PBS).Additionally,we used experimental results to discuss the response time and response voltage to compare vitamin C with orange juice for the vitamin C sensor.
文摘The application of Bluetooth on the pH sensor was accomplished.Based on the experimental results,Bluetooth technology was used to measure pH values without limiting the distance.Moreover,Biuetooth technology provides low power, low cost and small volume,therefore,it can increase the practicability of the system.In this investigation,the pH value was detected by the SnO_2/ITO glass-based pH sensor.During the signal progress,the detected signal was transferred to the microchip PIC18.After that,the microchip was able to communicate with PC by the Bluetooth.Moreover,the microchip can diagnose the sensing signal and sends the warning signal by alert function.In addition,the part of PC has the ability to record the information,builds the database for analyzing the pH values,and provides a better long-distance monitoring system.
