Printed Resistive Sensor Array Combined with a Flexible Substrate for Ethanol and Methane Detection

In this research, we combined printed electrodes and a flexible substrate to develop a low-cost, resistive, gas sensor with small energy consumption. The ability to measure a gas is derived from an analysis of the resistance change resulting from gas molecules adsorbed by a polymer. With the sensor array coated with various polymers, we can identify the gas type and its concentration. Eight combinations of electrode with different width and gap were designed. The electrodes were printed on PET substrates with silver ink. Sensing material developed with mixture of Polyvinylpyrrolidone (PNVP), Carbon Black (CB) and solvent ethylene glycol (EG) was then coated on the sensors and tested with ethanol and methane. The layout design of the width and gap with the greatest sensitivity towards gases is 20 μ m/20 μ m. The limit of detection (LOD) is 40 ppm for ethanol and 36 ppm for methane; the resistance changes of the two gases are apparently opposite. Besides this, sensors coated with other sensing materials developed with combination of CB,polymers, poly(4-vinylpyridine)(P4VP) and polystyrene (PS) with solvent, EG and Tetrahydofuran (THF) respectively were measured with gases at varied concentration to derive the sensitivity of each. According to these experiments, a flexible gas sensor shows a great potential to achieve the purpose of establishing a wearable sensing platform.