Aerosol jet printed temperature sensors using an environmentally friendly bilayer dielectric

Abstract

With the rise of the internet of things and applications such as smart packaging, the need for low cost, disposable temperature sensors with minimum environmental impact are critical. In this study, we report fully printed capacitive temperature sensors made from bio-degradable dielectric materials. All layers were aerosol jet printed and the areal capacitance was characterized at several temperatures between room temperature (22 ˚C) and 80 °C. Using a bilayer dielectric structure, a layer of poly (vinyl alcohol) (PVA) was encapsulated with polycaprolactone (PCL) through interfacial crosslinking to protect it against humidity. Various concentrations and layer amounts of PVA were investigated, with the most effective capacitors consisting of a single layer of PVA deposited from a 5.0 mg ml⁻¹ solution followed by a layer of the UV-crosslink-able PCL deposited from 2.0 mg ml⁻¹ solution, achieving a 43 ± 6% increase in areal capacitance at 80 °C when compared to room temperature, measured at a frequency of 501 Hz.