Flexible Atmospheric-Pressure Gas Ionization Sensors with Horizontally Aligned Carbon Nanotube Electrodes

A flexible atmospheric-pressure gas ionization sensor (GIS) with the horizontally aligned carbon nanotube (HACNT) electrodes in the planar structure has been demonstrated for the first time via the proposed rolling-down technique of CNTs. The gap between the electrodes of high-density and uniform HACNTs could be therefore precisely controlled via adjusting the length of the CNTs and the interspacing between the patterned catalysts. High-performance sensing characteristics to various gases Ar, N-2, air, and O-2 at atmospheric pressure with the breakdown voltages as low as 160, 193, 205, and 233, respectively, have been achieved with the electrode gap of 20 mu m. It is attributed to the field enhancement from the small gap and the double-side nanostructures. The superior flexibility of the proposed GIS with different bending tests has also been obtained. It reflects that the HACNTs possess excellent material properties, including great mechanical strength and good electrical conductivity. Such a simple, low-cost, and flexible GIS is promising for its applications in portable and wearable personal monitoring devices.