Effect of Surface Network of Single Wall Nanotube on DMMP Response Deepak Kumar1,2, Poornendu Chaturvedi1, Praveen Saho1 , Abhilasha Chouksey1, R. P. Tandon2 and P. K. Chaudhury1 1Solid
State Physics Laboratory, Lucknow Road, Timarpur, Delhi-110054, India, 2Department of Physics and Astrophysics, University of Delhi, Delhi-11007, India ABSTRACT The response of Dimethyl methylphosphonate (DMMP), a simulant of chemical warfare agent Sarin is investigated towards thick random network and micro aligned network of SWNT. For gas sensing study, a thick random network and micro aligned network is Application as a chemical/gas sensor prepared by vacuum filtration and dielectrophoresis respectively. The surface area network of these gas sensors is investigated with SEM. The thick film resistor (CNT-TFR) has less baseline noise as compared to micro aligned resistor (CNT-µR). The response of these gas sensors is studied by exposing increasing concentration of DMMP from 50 ppm to 1000 ppm and then decreased back to 50 ppm. CNT-µR gives more response to 1000 ppm DMMP as compared to CNT-TFR.
INTRODUCTION Lower operating temperature
Higher sensitivity
Chemical Vapor Deposition(CVD)
Spin Coating
CNT gas sensor fabrication
CNT gas sensor properties
Selective
DEVICE FABRICATION
Faster response
Vacuum filtration method
Dielectrophoresis (DEP)
Film preparation
Device Preparation
1. P2-SWNT dispersed in DMF
1. P2-SWNT in DMF
dispersed
FUNCTION GENERATOR RESISTANCE
2. Pattern Electrodes for DEP on Si substrate
2. The dispersion filtrated over polycarbonate membrane
OSCILLOSCOPE
DISPERSION BUBBLE
SILICON SUBSTRATE
3. Dielectrophoresis (DEP)
3. Cr/Au Metal contacts were deposited with the help of sputtering Vacuum filtration method
4. Aligned CNT between electrodes
Electrode Pad
Dielectrophoresis method
RESULTS & DISCUSSION CNT-µR
Wire bonded sensor
SEM of Thin film Resistor(TFR)
DEP Resistor
Gas sensor mounted in gas cell SEM of DEP Device
Thin film Resistor
Change in response w.r.t time after exposure of different concentration of DMMP
The response curves are overlaid, CNTµR shows saturation behavior for increasing concentration
The response curves are overlaid, CNTµR shows saturation behavior for decreasing concentration
CNT-TFR
Change in response w.r.t time after exposure of different concentration of DMMP
The response curves are overlaid to show the different slope obtained for each increasing concentration
CONCLUSIONS 1. CNT-µR gives more response to DMMP as compare to CNT-TFR 2. CNT-µR shows the saturation behavior for exposed DMMP concentration 3. CNT-TFR has less baseline noise as compared to CNT-µR 4. Gas sensor gives repeatable behavior for 500 ppm DMMP
The response curves are overlaid to show the different slope obtained for each decreasing concentration
Change in response w.r.t time with multiple exposure of DMMP
REFERENCES 1. H.J. Lee, P. Kwan Kyu, O. Oralkan, M. Kupnik, B.T. Khuri-Yakub, CMUT as a chemical sensor for DMMP detection, Frequency Control Symposium, 2008 IEEE International2008, pp. 434-9. 2. M. Lucci, P. Regoliosi, A. Reale, A. Di Carlo, S. Orlanducci, E. Tamburri, et al., Gas sensing using single wall carbon nanotubes ordered with dielectrophoresis Sensors and Actuators B: Chemical, 111-112(2005) 181-6. 3. W. Yanyan, Z. Zhihua, Y. Zhi, C. Xiaohang, X. Dong, Z. Yafei, Gas sensors based on deposited single-walled carbon nanotube networks for DMMP detection, Nanotechnology, 20(2009) 345502.