Wearable sensors are pivotal for point-of-care diagnostics,yet their application in extreme conditions is rarely conducted.In this work,we present a wearable pH sensor using tungsten oxide aerogel(TOA)as the sensing m...Wearable sensors are pivotal for point-of-care diagnostics,yet their application in extreme conditions is rarely conducted.In this work,we present a wearable pH sensor using tungsten oxide aerogel(TOA)as the sensing material.With the advantages of large specific surface area,high porosity and interconnected network structures,TOA not only provides excellent pH sensing performance but also demonstrates remarkable structural and sensing stability.The potentiometric pH sensor exhibits a high sensitivity(−63.70 mV/pH),a low detectable limit(0.05)and a superior stability(maintained over 50,000 s).Integrated with a Bluetooth module,the wearable sensor achieves non-invasive and real-time pH monitoring on the human skin with minimal deviation(1.91%)compared to the commercial pH meter.More importantly,the anti-impact behaviors of the TOA-based sensing materials and chip,along with the pH wearable sensor on a pig exhibit an outstanding shock-resistance ability,with variations no more than 7.17%under an impact of 118.38 kPa.Therefore,this study shows great promise for the aerogel-based personalized health management in the extreme environment.展开更多
Several p H-dependent processes and reactions take place in the human body;hence,the p H of body fluids is the best indicator of disturbed health conditions.However,accurate and real-time diagnosis of the p H of body ...Several p H-dependent processes and reactions take place in the human body;hence,the p H of body fluids is the best indicator of disturbed health conditions.However,accurate and real-time diagnosis of the p H of body fluids is complicated because of limited commercially available p H sensors.Hence,we aimed to prepare a flexible,transparent,disposable,userfriendly,and economic strip-based solid-state p H sensor using palladium nanoparticles(Pd NPs)/N-doped carbon(NC)composite material.The Pd NPs/NC composite material was synthesized using wool keratin(WK)as a precursor.The insitu prepared Pd NPs played a key role in the controlled switching of protein structure to the N-doped carbon skeleton withπ–πarrangement at the mesoscale level,which mimics the A–B type polymeric structure,and hence,is highly susceptible to H+ions.The optimized carbonization condition in the presence of Pd NPs showed that the material obtained using a modified Ag/Ag Cl reference electrode had the highest p H sensitivity with excellent stability and durability.The optimized p H sensor showed high specificity and selectivity with a sensitivity of 55 m V/p H unit and a relative standard deviation of 0.79%.This study is the first to synthesize Pd NPs using WK as a stabilizing and reducing agent.The applicability of the sensor was investigated for biological samples,namely,saliva and gastric juices.The proposed protocol and material have implications in solid-state chemistry,where biological material will be the best choice for the synthesis of materials with anticipated performance.展开更多
A new solvent polymeric membrane (SPM)pH2sensor based on 4,4'-bis (N, N-didecylamino)methyl)azobenzene as neutral carricr has been reported. It has excellent pH response characteristics with the linear response ra...A new solvent polymeric membrane (SPM)pH2sensor based on 4,4'-bis (N, N-didecylamino)methyl)azobenzene as neutral carricr has been reported. It has excellent pH response characteristics with the linear response range (1.7—13.2)much wider than that of similar SPM pH sensors reported so far. The sensor has a theoretical Nernstian response of 57.4+0.2V/pH(at 20℃)without super—Nernstian response phenomenon.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
In recent years there has increased interest in the characterization of titanium oxide nanorods for application in analytical devices. The titanium oxide nanorods (NRTiO) were obtained by hydrothermal reaction with a ...In recent years there has increased interest in the characterization of titanium oxide nanorods for application in analytical devices. The titanium oxide nanorods (NRTiO) were obtained by hydrothermal reaction with a NaOH solution heated in the autoclave at 150°C for up to 50 h. Experimental data indicate that the prepared nanorods consist of anatase and rutile phases, with a possible interlayer structure. The NRTiO was investigated as pH sensor in the pH range 2 - 12, and the extended gate field effect transistor (EGFET) configuration presented a sensitivity of 49.6 mV/pH. Voltammetric data showed a sensitivity of 47.8 mV/pH. These results indicate that the material is a promising candidate for applications as an EGFET-pH sensor and as a disposable biosensor in the future.展开更多
Wound healing has been recognized as a complex and dynamic regeneration process and attracted increasing interests on its management.For effective wound healing management,a continuous monitoring on the wound healing ...Wound healing has been recognized as a complex and dynamic regeneration process and attracted increasing interests on its management.For effective wound healing management,a continuous monitoring on the wound healing based on sensors is essential.Since pH has been found to play an important role on wound healing process,a variety of pH sensors systems for wound healing monitoring have been greatly developed in recent years.Among these pH sensors,flexible and wearable pH sensors which can be incorporated with wound dressing have gained much attention.In this review,the recent advances in the development of flexible and wearable pH sensors for wound healing monitoring have been comprehensive summarized from the range of optical and electrochemical bases.展开更多
The key factor of the sensitivity in the FBG-based pH sensor is analyzed in detail. A multi-thin-layer structure of the gel coated cover was proposed and implemented with a special process. The sensors with the coated...The key factor of the sensitivity in the FBG-based pH sensor is analyzed in detail. A multi-thin-layer structure of the gel coated cover was proposed and implemented with a special process. The sensors with the coated thickness of 420 ~m, 500 ~m, and 580 ~m were built up, respectively. The corresponding spectral shifts of 0.08nm, 0.13nm, and 0.22nm were detected when the pH sensors were soaked in the pH value of 3-9. Meanwhile, the sensor with the gel layer thickness of 580 ~tm was measured in the optimum measurement time period with the pH value changing from 3-12, in which the detected sensitivity of 52pm/pH was achieved in the pH range of 6-12.展开更多
An optical pH sensitive membrane for optical pH sensors has been developed by covalently immobilizing phenol red on optical transparent cross-linked polyvinyl alcohol （PVA） membrane surfaces. The phenol red was firs...An optical pH sensitive membrane for optical pH sensors has been developed by covalently immobilizing phenol red on optical transparent cross-linked polyvinyl alcohol （PVA） membrane surfaces. The phenol red was first reacted with acrylamide to form a product of acrylamide grafted phenol red （AAGP）, then the AAGP was covalently immobilized to the PVA membrane via surface grafting-polymerization using Fe^2＋/H2O2 as initiator. The performance of the pH sensitive membrane was investigated and the results showed that the pH sensitive membrane has some features including a linear response scope from pH 6.5 to 8.5 closed with phenol solution, a rapid response time （〈：20 s）, good reproducibility, reversibility, excellent stability and easiness of fabrication. These show that the pH sensitive membrane can be used as a sensitive layer for optical pH sensor.展开更多
Research into new pH sensors fabricated by the standard CMOS process is currently a hot topic. The new pH sensing multi-floating gate field effect transistor is found to have a very large threshold voltage, which is d...Research into new pH sensors fabricated by the standard CMOS process is currently a hot topic. The new pH sensing multi-floating gate field effect transistor is found to have a very large threshold voltage, which is different from the normal ion-sensitive field effect transistor. After analyzing all the interface layers of the structure, a new sensitive model based on the Gauss theorem and the charge neutrality principle is created in this paper. According to the model, the charge trapped on the multi-floating gate during the process and the thickness of the sensitive layer are the main causes of the large threshold voltage. From this model, it is also found that removing the charge on the multi-floating gate is an effective way to decrease the threshold voltage. The test results for three different standard pH buffer solutions show the correctness of the model and point the way to solve the large threshold problem.展开更多
We demonstrate a pH sensor based on ultrasensitive nanosize Schottky junctions formed within bottom-up grown dopant-flee arrays of assembled silicon nanowires. A new measurement concept relying on a continuous gate sw...We demonstrate a pH sensor based on ultrasensitive nanosize Schottky junctions formed within bottom-up grown dopant-flee arrays of assembled silicon nanowires. A new measurement concept relying on a continuous gate sweep is presented, which allows the straightforward determination of the point of maximum sensitivity of the device and allows sensing experiments to be performed in the optimum regime. Integration of devices into a portable fluidic system and an electrode isolation strategy affords a stable environment and enables long time robust FET sensing measurements in a liquid environment to be carried out. Investigations of the physical and chemical sensitivity of our devices at different pH values and a comparison with theoretical limits are also discussed. We believe that such a combination of nanofabrication and engineering advances makes this Schottky barrier-powered silicon nanowire lab-on-a-chip platform suitable for efficient biodetection and even for more complex biochemical analysis.展开更多
The fabrication of nano porous silicon, nPSi, using alkali etching process has been studied and carried out. The surface chemistry of anisotropic etching of n-type Si-wafer is reviewed and the anisotropic chemical etc...The fabrication of nano porous silicon, nPSi, using alkali etching process has been studied and carried out. The surface chemistry of anisotropic etching of n-type Si-wafer is reviewed and the anisotropic chemical etching of silicon in alkaline solution using wetting agents is discussed. Transformation of crystallographic plane of n-Si (211) to nPSi (100) has occurred on using n-propanol as wetting agent. The rate of pore formation was 0.02478 - 0.02827 μm/min, which was heavily dependent upon the concentration of the etchant containing wetting agents, allowing patterned porous silicon formation through selective doping of the substrate. A particle size of 15 nm for porous nano-silicon was calculated from the XRD data. Porosity of PS layers is about 10%. Pore diameter and porous layer thickness are 0.0614 nm and 16 μm, respectively. The energy gap of the produced porous silicon is 3.3 eV. Furthermore, the combination of PS with Congo Red, which are nanostructured due to their deposition within the porous matrix is discussed. Such nano compounds offer broad avenue of new and interesting properties depending on the involved materials as well as on their morphology. Chemical route was utilized as the host material to achieve pores filling. They were impregnated with Congo Red, which gave good results for the porous silicon as a promising pH sensor.展开更多
Whether in the monitoring of critically ill patients such as shock, respiratory failure, brain injury, or in major anesthesia surgeries, it is necessary to evaluate the patient’s pO<sub>2</sub> and pH. An...Whether in the monitoring of critically ill patients such as shock, respiratory failure, brain injury, or in major anesthesia surgeries, it is necessary to evaluate the patient’s pO<sub>2</sub> and pH. An optical fiber sensor presented is capable of monitoring the presence of oxygen partial pressure (pO<sub>2</sub>) and pH in the real-time. The sensor is based on fluorescence sensing of polymer immobilized in the oxygen/pH-sensitive membranes and covalently attached to the optical fiber probe. The design of this sensor uses LED as light source, which is an excitation light source, inducing specific wavelengths of fluorescence on the oxygen/pH-sensitive membrane. The intensity and lifetime of fluorescence are related to the pO<sub>2</sub> and pH. So the pO<sub>2</sub> and pH can be measured by the relationship between the pO<sub>2</sub>/pH values and the intensity and lifetime of fluorescence. The signal conditioning system based on DSP and STM32 was used to store and process data, and display test values. The response of the sensor for pO<sub>2</sub> and pH monitoring with nitrogen (N<sub>2</sub>) as a balancing gas in the laboratory was performed. Finally, the oxygen/pH sensing scheme presented in this work is intended for using in biological, medical and environmental applications.展开更多
基金supported by the National Natural Science Foundation of China(Nos.22374119 and 22274127)the Research Fund of the State Key Laboratory of Solidification Processing(NPU),China(No.2021-QZ-01)+1 种基金the Key Project of Natural Science Fund of Shaanxi Province(Nos.2023-JC-ZD-06 and 2024JC-YBQN-0636)the Open Project of the State Key Laboratory of Transducer Technology(No.SKT2307).
文摘Wearable sensors are pivotal for point-of-care diagnostics,yet their application in extreme conditions is rarely conducted.In this work,we present a wearable pH sensor using tungsten oxide aerogel(TOA)as the sensing material.With the advantages of large specific surface area,high porosity and interconnected network structures,TOA not only provides excellent pH sensing performance but also demonstrates remarkable structural and sensing stability.The potentiometric pH sensor exhibits a high sensitivity(−63.70 mV/pH),a low detectable limit(0.05)and a superior stability(maintained over 50,000 s).Integrated with a Bluetooth module,the wearable sensor achieves non-invasive and real-time pH monitoring on the human skin with minimal deviation(1.91%)compared to the commercial pH meter.More importantly,the anti-impact behaviors of the TOA-based sensing materials and chip,along with the pH wearable sensor on a pig exhibit an outstanding shock-resistance ability,with variations no more than 7.17%under an impact of 118.38 kPa.Therefore,this study shows great promise for the aerogel-based personalized health management in the extreme environment.
基金supported by the National Natural Science Foundation of China(Grant Nos.51502253,U1405226,21503175,and 21705135)Natural Science Foundation of Guangdong Province,China(Grant No.2016A030310369)Natural Science Foundation of Fujian Province,China(Grant No.2017J01104)。
文摘Several p H-dependent processes and reactions take place in the human body;hence,the p H of body fluids is the best indicator of disturbed health conditions.However,accurate and real-time diagnosis of the p H of body fluids is complicated because of limited commercially available p H sensors.Hence,we aimed to prepare a flexible,transparent,disposable,userfriendly,and economic strip-based solid-state p H sensor using palladium nanoparticles(Pd NPs)/N-doped carbon(NC)composite material.The Pd NPs/NC composite material was synthesized using wool keratin(WK)as a precursor.The insitu prepared Pd NPs played a key role in the controlled switching of protein structure to the N-doped carbon skeleton withπ–πarrangement at the mesoscale level,which mimics the A–B type polymeric structure,and hence,is highly susceptible to H+ions.The optimized carbonization condition in the presence of Pd NPs showed that the material obtained using a modified Ag/Ag Cl reference electrode had the highest p H sensitivity with excellent stability and durability.The optimized p H sensor showed high specificity and selectivity with a sensitivity of 55 m V/p H unit and a relative standard deviation of 0.79%.This study is the first to synthesize Pd NPs using WK as a stabilizing and reducing agent.The applicability of the sensor was investigated for biological samples,namely,saliva and gastric juices.The proposed protocol and material have implications in solid-state chemistry,where biological material will be the best choice for the synthesis of materials with anticipated performance.
基金Project supported by the National Natural Science Foundation of China partially by Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Academia Sinica.
文摘A new solvent polymeric membrane (SPM)pH2sensor based on 4,4'-bis (N, N-didecylamino)methyl)azobenzene as neutral carricr has been reported. It has excellent pH response characteristics with the linear response range (1.7—13.2)much wider than that of similar SPM pH sensors reported so far. The sensor has a theoretical Nernstian response of 57.4+0.2V/pH(at 20℃)without super—Nernstian response phenomenon.
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.
基金This work was supported by FAPESP,FAPEMIG,CNPq and CAPES
文摘In recent years there has increased interest in the characterization of titanium oxide nanorods for application in analytical devices. The titanium oxide nanorods (NRTiO) were obtained by hydrothermal reaction with a NaOH solution heated in the autoclave at 150°C for up to 50 h. Experimental data indicate that the prepared nanorods consist of anatase and rutile phases, with a possible interlayer structure. The NRTiO was investigated as pH sensor in the pH range 2 - 12, and the extended gate field effect transistor (EGFET) configuration presented a sensitivity of 49.6 mV/pH. Voltammetric data showed a sensitivity of 47.8 mV/pH. These results indicate that the material is a promising candidate for applications as an EGFET-pH sensor and as a disposable biosensor in the future.
基金supported by the National Natural Science Foundation of China (No. 51703102)the Innovation and Entrepreneurship Training Program for College Students of Qingdao University (2019)
文摘Wound healing has been recognized as a complex and dynamic regeneration process and attracted increasing interests on its management.For effective wound healing management,a continuous monitoring on the wound healing based on sensors is essential.Since pH has been found to play an important role on wound healing process,a variety of pH sensors systems for wound healing monitoring have been greatly developed in recent years.Among these pH sensors,flexible and wearable pH sensors which can be incorporated with wound dressing have gained much attention.In this review,the recent advances in the development of flexible and wearable pH sensors for wound healing monitoring have been comprehensive summarized from the range of optical and electrochemical bases.
文摘The key factor of the sensitivity in the FBG-based pH sensor is analyzed in detail. A multi-thin-layer structure of the gel coated cover was proposed and implemented with a special process. The sensors with the coated thickness of 420 ~m, 500 ~m, and 580 ~m were built up, respectively. The corresponding spectral shifts of 0.08nm, 0.13nm, and 0.22nm were detected when the pH sensors were soaked in the pH value of 3-9. Meanwhile, the sensor with the gel layer thickness of 580 ~tm was measured in the optimum measurement time period with the pH value changing from 3-12, in which the detected sensitivity of 52pm/pH was achieved in the pH range of 6-12.
基金Project supported by the National Natural Science Foundation of China （Nos. 50273037 and 20465001）.
文摘An optical pH sensitive membrane for optical pH sensors has been developed by covalently immobilizing phenol red on optical transparent cross-linked polyvinyl alcohol （PVA） membrane surfaces. The phenol red was first reacted with acrylamide to form a product of acrylamide grafted phenol red （AAGP）, then the AAGP was covalently immobilized to the PVA membrane via surface grafting-polymerization using Fe^2＋/H2O2 as initiator. The performance of the pH sensitive membrane was investigated and the results showed that the pH sensitive membrane has some features including a linear response scope from pH 6.5 to 8.5 closed with phenol solution, a rapid response time （〈：20 s）, good reproducibility, reversibility, excellent stability and easiness of fabrication. These show that the pH sensitive membrane can be used as a sensitive layer for optical pH sensor.
基金Project supported by the National Natural Science Foundation of China (No.60576050)
文摘Research into new pH sensors fabricated by the standard CMOS process is currently a hot topic. The new pH sensing multi-floating gate field effect transistor is found to have a very large threshold voltage, which is different from the normal ion-sensitive field effect transistor. After analyzing all the interface layers of the structure, a new sensitive model based on the Gauss theorem and the charge neutrality principle is created in this paper. According to the model, the charge trapped on the multi-floating gate during the process and the thickness of the sensitive layer are the main causes of the large threshold voltage. From this model, it is also found that removing the charge on the multi-floating gate is an effective way to decrease the threshold voltage. The test results for three different standard pH buffer solutions show the correctness of the model and point the way to solve the large threshold problem.
文摘We demonstrate a pH sensor based on ultrasensitive nanosize Schottky junctions formed within bottom-up grown dopant-flee arrays of assembled silicon nanowires. A new measurement concept relying on a continuous gate sweep is presented, which allows the straightforward determination of the point of maximum sensitivity of the device and allows sensing experiments to be performed in the optimum regime. Integration of devices into a portable fluidic system and an electrode isolation strategy affords a stable environment and enables long time robust FET sensing measurements in a liquid environment to be carried out. Investigations of the physical and chemical sensitivity of our devices at different pH values and a comparison with theoretical limits are also discussed. We believe that such a combination of nanofabrication and engineering advances makes this Schottky barrier-powered silicon nanowire lab-on-a-chip platform suitable for efficient biodetection and even for more complex biochemical analysis.
文摘The fabrication of nano porous silicon, nPSi, using alkali etching process has been studied and carried out. The surface chemistry of anisotropic etching of n-type Si-wafer is reviewed and the anisotropic chemical etching of silicon in alkaline solution using wetting agents is discussed. Transformation of crystallographic plane of n-Si (211) to nPSi (100) has occurred on using n-propanol as wetting agent. The rate of pore formation was 0.02478 - 0.02827 μm/min, which was heavily dependent upon the concentration of the etchant containing wetting agents, allowing patterned porous silicon formation through selective doping of the substrate. A particle size of 15 nm for porous nano-silicon was calculated from the XRD data. Porosity of PS layers is about 10%. Pore diameter and porous layer thickness are 0.0614 nm and 16 μm, respectively. The energy gap of the produced porous silicon is 3.3 eV. Furthermore, the combination of PS with Congo Red, which are nanostructured due to their deposition within the porous matrix is discussed. Such nano compounds offer broad avenue of new and interesting properties depending on the involved materials as well as on their morphology. Chemical route was utilized as the host material to achieve pores filling. They were impregnated with Congo Red, which gave good results for the porous silicon as a promising pH sensor.
文摘Whether in the monitoring of critically ill patients such as shock, respiratory failure, brain injury, or in major anesthesia surgeries, it is necessary to evaluate the patient’s pO<sub>2</sub> and pH. An optical fiber sensor presented is capable of monitoring the presence of oxygen partial pressure (pO<sub>2</sub>) and pH in the real-time. The sensor is based on fluorescence sensing of polymer immobilized in the oxygen/pH-sensitive membranes and covalently attached to the optical fiber probe. The design of this sensor uses LED as light source, which is an excitation light source, inducing specific wavelengths of fluorescence on the oxygen/pH-sensitive membrane. The intensity and lifetime of fluorescence are related to the pO<sub>2</sub> and pH. So the pO<sub>2</sub> and pH can be measured by the relationship between the pO<sub>2</sub>/pH values and the intensity and lifetime of fluorescence. The signal conditioning system based on DSP and STM32 was used to store and process data, and display test values. The response of the sensor for pO<sub>2</sub> and pH monitoring with nitrogen (N<sub>2</sub>) as a balancing gas in the laboratory was performed. Finally, the oxygen/pH sensing scheme presented in this work is intended for using in biological, medical and environmental applications.
