Design and Characterization of a Flexible Pressure Sensor Using Starch‐Based Biopolymer Films Doped with Electrographite

Sustainable soft sensors are increasingly integral to wearable systems and human–machine interfaces; however, many current implementations depend on petroleum-derived elastomers and complex microfabrication. In this context, biopolymer-based conductive composites provide a complementary pathway toward low-cost, water-based processing and more environmentally responsible sensing architectures. This work reports a proof-of-concept pressure sensor based on a starch-derived biopolymer film doped with electrographite powder. The sensing layer, fabricated by spin coating, is integrated into an aluminum/biopolymer/aluminum sandwich configuration supported on an acetate substrate. Electrical resistance measurements under compressive loading (10–1000 g applied over 5.06 cm²; 0.2–20 kPa) show that the neat starch film remains electrically insulating, whereas the electrographite-doped film exhibits a clear piezoresistive response, with resistance decreasing as load increases. Compared with graphite-doped films, electrographite provides a more consistent response and a low hysteresis (<5%) in representative loading–unloading curves under the reported protocol. These results support the feasibility of using a biobased, starch-based sensing layer for low-cost flexible sensing concepts.