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
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.
