Dielectrophoretically Assembled SWCNTs Networks on SU-8 Substrate for PEG/SWCNTs Composite Gas Sensor.

This study proposed a SU-8 based gas sensor, integrated with heater and sensing electrodes, to develop a multi-channel gas sensor with PEG/SWCNTs composite films. The impedance of single-walled carbon nanotubes (SWCNTs) on each sensing electrode was well controlled via dielectrophoresis technology. To investigate dielectrophoretic mobility characteristics, the concentric circular sensing electrode has three different spacing between the inner and outer electrodes, including 10 μm, 15 μm, and 20 μm. The electrodes were applied with a 5 MHz AC source with a voltage ranging from 1 Vpp to 5 Vpp. Polyethylene glycol (PEG) was deposited on the gas sensor via drop casting. The fabricated gas sensor was operated at different working temperatures, including 25 °C, 40 °C, 50 °C and 60 °C, to examine the sensing response. The response results revealed that the PEG/SWCNTs composites gas sensor with 60 °C working temperature exhibited the ability to detect 80 ppm ethanol vapor.