Film Morphology Effect on VOC Sensor Performance Fabricated by Drop-On-Demand Inkjet-Printing

This paper presents a sensor for detecting volatile organic compounds with an inkjet-printed composite. The sensing material is composed of polystyrene (35 kg/mol molecular weight) and a high structure carbon black, Ketjenblack EC-600JD. We used a dual-solvent system for ink formulation and compared its print morphology, and sensing performance with a single-solvent system. The dual solvent system improved droplet formation and minimized coffee ring formation. The sensor response to acetone and ethanol was studied. We observed a 2-fold improved sensitivity due to the absence of the coffee ring effect, which is presumably linked to more uniformity of the surface and fewer variations in the film thickness. Moreover, a superior sensor response/recovery time was obtained by using a dedicated print strategy, e.g., inter-droplet spacing and print pattern layout.