All Printed Flexible Piezoelectric Pressure Sensor with Interdigitated Electrodes

Owing to their cost-effective fabrication, skin-conformability, and charge generation, printed flexible piezoelectric pressure sensors based on poly(vinylidenefluoride-co-trifluoroethylene) P(VDF-TrFE) have high potential to be used in affordable, unobtrusive and energy-autonomous systems for various healthcare and robotics applications. This study presents a simple two printing step fabrication process for a thin (overall thickness of ~11 μm) flexible piezoelectric sensor based on an interdigitated electrode (IDE) structure. Inkjet printing is used to fabricate a poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) IDE structure with an electrode gap width of 67.9 ± 9.4 μm and an electrode width of 137.8 ± 17.5 μm on a Parylene-C substrate. This is followed by bar coating a layer of piezoelectric polymer (P(VDF-TrFE)) of 9.6 ± 0.9 μm thick. The optimal electric field for poling the piezoelectric material is 50 V/μm which results in a remanent polarization of 5.2 ± 1.0 μC/cm2. The piezoelectric sensitivity was measured in normal mode obtaining a result of 3.9 ± 0.5 pC/N. In conclusion, this study demonstrates the potential of additive fabrication technologies to develop low-cost and conformal piezoelectric pressure sensors.