<正>SnO_2 thin film sensors were fabricated by a thermal evaporation method.The sensors were heated for thermal oxidation.For high porosity,SnO_2 thin film sensors were treated in a N_2 atmosphere.The sensors th...<正>SnO_2 thin film sensors were fabricated by a thermal evaporation method.The sensors were heated for thermal oxidation.For high porosity,SnO_2 thin film sensors were treated in a N_2 atmosphere.The sensors that were treated with O_2 after being treated with N_2 showed 70 % sensitivity for 1×10~ -6) of H_2S,which is higher than the sensors that were only treated with O_2.The Ni metal,as a catalyst,was evaporated on the thin film Sn on the Al_2O_3 substrate.The sensor was heated to grow the Sn nanowire in a tube furnace with N_2 flow.Sn nanowire was heated for oxidation.The sensitivity of SnO_2 nanowire sensor was measured for 500×10~ -9) of H_2S.The selectivity of the SnO_2 nanowire sensor was compared with the thin film and the thick film SnO_2.Each sensor was measured for H_2S,CO,and NH_3 in this study.展开更多
Hydrophobic polymer [ex.Poly(vinylidenfluoride)] layer was coated on polyaniline (PANi) sensor to reduce the problems of humidity.The differences in sensitivity to methanol gas detection in various humidity condition ...Hydrophobic polymer [ex.Poly(vinylidenfluoride)] layer was coated on polyaniline (PANi) sensor to reduce the problems of humidity.The differences in sensitivity to methanol gas detection in various humidity condition between pure-PANi sensor and coated with poly(vinylidenfluoride) polymer (PVDF) (coated-PANi sensor) were investigated.Also the relation between the density of pore,which was coated on the layer of the PANi sensor,and sensitivity was investigated.To fabricate the porous PVDF layer on PANi sensor,poly(vinylalcohol) (PVA),which is water-soluble polymer,was used. Coated-PANi sensor was less affected by humidity compared with pure-PANi sensor.And higher density of pore on PVDF layer led to higher sensitivity.展开更多
In this paper,an improvement in sensitivity and recovery of the single-walled carbon nanotube (SWNT)-based gas sensors was reported.The sensors were fabricated from SWNT powder by a screen-printing method,followed by ...In this paper,an improvement in sensitivity and recovery of the single-walled carbon nanotube (SWNT)-based gas sensors was reported.The sensors were fabricated from SWNT powder by a screen-printing method,followed by annealing for 2 h in open-air at various temperatures.The Raman spectra of the SWNT bundles and the response to ammonia (NH_3) exposure of the sensors indicated that the annealing at a relevant temperature improved the sensor sensitivity.The sensor annealed at 200℃exhibited a high sensitivity in NH_3 detection.After 20 min of exposure to NH_3 at room temperature,the resistance of the sensor increased up to 12% in comparison with its initial value.By evacuating combined with maintaining the flux of carrier gas at 300 sccm,the sensor recovery was significantly speeded.The sensor resistance retrieved to its initial value after only 25 min degassing. These results would be considered in the development of the SWNT-based gas sensors.展开更多
We investigated the gas sensing characteristics of rutile and anatase TiO_2 nano-particle sensors for chemical warfare agents.TiO_2 nano-powders with rutile and anatase structure were fabricated by controlling pH valu...We investigated the gas sensing characteristics of rutile and anatase TiO_2 nano-particle sensors for chemical warfare agents.TiO_2 nano-powders with rutile and anatase structure were fabricated by controlling pH value without heat treatment respectively.The mean particle size of TiO_2 powders were below 10 nm.As-prepared TiO_2 powders have several advantages of nano particle size and high surface area and could be a prominent candidate for nano-sensors.TiO_2 sensors were examined with DMMP for chemical warfare agents detection.展开更多
Polypyrrole (PPy) powder was synthesized by chemical polymerization at 0℃under atmospheric condition and its layer was prepared by dip coating method on the alumina substrate with interdigitated electrodes.The influ...Polypyrrole (PPy) powder was synthesized by chemical polymerization at 0℃under atmospheric condition and its layer was prepared by dip coating method on the alumina substrate with interdigitated electrodes.The influence of relative humidity (RH 0～70%) to PPy sensor was studied.The measuring temperature was fixed at 25℃.Methanol and benzene were used as target gases.Various analytic techniques were examined to observe changes in the properties of PPy sensor.The sensitivity of PPy sensor to water vapor was linearly increased with the increasing humidity.As the relative humidity increase from 0% to 70%,the sensitivities to methanol and benzene vapor were reduced,and reduction ratio of sensitivity was 94%, 92.5% at RH 70%,respectively.展开更多
Conducting polymers sensors have been very interesting that it can detect wide variety of functionalities,however these materials have to solve humidity contaminant,poor reversibility and selectivity.To improve this p...Conducting polymers sensors have been very interesting that it can detect wide variety of functionalities,however these materials have to solve humidity contaminant,poor reversibility and selectivity.To improve this problems,we investigated pretreatment such as soaking in methanol and thermal treatment in N_2.This process improved stability, reversibility and response time and recovery time.To overcome humidity contaminant coated hydrophobic polymer was reduced above 50% at RH10%.For sensor array structure was fabricated for enhancing selectivity of gas vapor.Conducting polymer sensor array had several application in environmental and medical science the method of principal component analysis.展开更多
文摘<正>SnO_2 thin film sensors were fabricated by a thermal evaporation method.The sensors were heated for thermal oxidation.For high porosity,SnO_2 thin film sensors were treated in a N_2 atmosphere.The sensors that were treated with O_2 after being treated with N_2 showed 70 % sensitivity for 1×10~ -6) of H_2S,which is higher than the sensors that were only treated with O_2.The Ni metal,as a catalyst,was evaporated on the thin film Sn on the Al_2O_3 substrate.The sensor was heated to grow the Sn nanowire in a tube furnace with N_2 flow.Sn nanowire was heated for oxidation.The sensitivity of SnO_2 nanowire sensor was measured for 500×10~ -9) of H_2S.The selectivity of the SnO_2 nanowire sensor was compared with the thin film and the thick film SnO_2.Each sensor was measured for H_2S,CO,and NH_3 in this study.
文摘Hydrophobic polymer [ex.Poly(vinylidenfluoride)] layer was coated on polyaniline (PANi) sensor to reduce the problems of humidity.The differences in sensitivity to methanol gas detection in various humidity condition between pure-PANi sensor and coated with poly(vinylidenfluoride) polymer (PVDF) (coated-PANi sensor) were investigated.Also the relation between the density of pore,which was coated on the layer of the PANi sensor,and sensitivity was investigated.To fabricate the porous PVDF layer on PANi sensor,poly(vinylalcohol) (PVA),which is water-soluble polymer,was used. Coated-PANi sensor was less affected by humidity compared with pure-PANi sensor.And higher density of pore on PVDF layer led to higher sensitivity.
文摘In this paper,an improvement in sensitivity and recovery of the single-walled carbon nanotube (SWNT)-based gas sensors was reported.The sensors were fabricated from SWNT powder by a screen-printing method,followed by annealing for 2 h in open-air at various temperatures.The Raman spectra of the SWNT bundles and the response to ammonia (NH_3) exposure of the sensors indicated that the annealing at a relevant temperature improved the sensor sensitivity.The sensor annealed at 200℃exhibited a high sensitivity in NH_3 detection.After 20 min of exposure to NH_3 at room temperature,the resistance of the sensor increased up to 12% in comparison with its initial value.By evacuating combined with maintaining the flux of carrier gas at 300 sccm,the sensor recovery was significantly speeded.The sensor resistance retrieved to its initial value after only 25 min degassing. These results would be considered in the development of the SWNT-based gas sensors.
文摘We investigated the gas sensing characteristics of rutile and anatase TiO_2 nano-particle sensors for chemical warfare agents.TiO_2 nano-powders with rutile and anatase structure were fabricated by controlling pH value without heat treatment respectively.The mean particle size of TiO_2 powders were below 10 nm.As-prepared TiO_2 powders have several advantages of nano particle size and high surface area and could be a prominent candidate for nano-sensors.TiO_2 sensors were examined with DMMP for chemical warfare agents detection.
文摘Polypyrrole (PPy) powder was synthesized by chemical polymerization at 0℃under atmospheric condition and its layer was prepared by dip coating method on the alumina substrate with interdigitated electrodes.The influence of relative humidity (RH 0～70%) to PPy sensor was studied.The measuring temperature was fixed at 25℃.Methanol and benzene were used as target gases.Various analytic techniques were examined to observe changes in the properties of PPy sensor.The sensitivity of PPy sensor to water vapor was linearly increased with the increasing humidity.As the relative humidity increase from 0% to 70%,the sensitivities to methanol and benzene vapor were reduced,and reduction ratio of sensitivity was 94%, 92.5% at RH 70%,respectively.
文摘Conducting polymers sensors have been very interesting that it can detect wide variety of functionalities,however these materials have to solve humidity contaminant,poor reversibility and selectivity.To improve this problems,we investigated pretreatment such as soaking in methanol and thermal treatment in N_2.This process improved stability, reversibility and response time and recovery time.To overcome humidity contaminant coated hydrophobic polymer was reduced above 50% at RH10%.For sensor array structure was fabricated for enhancing selectivity of gas vapor.Conducting polymer sensor array had several application in environmental and medical science the method of principal component analysis.
