Cellulose-Based Nanosponges with PEDOT:PSS as Pressure Sensors with Tunable Elasticity: A Study on Modulation of Mechanical Properties and Pressure Response

This study investigates the suitability of sustainable, highly porous nanosponges, composed of TEMPO-oxidized cellulose nanofibers (TOCNF) and branched polyethylenimine (bPEI, cross-linker), as scaffolds for PEDOT:PSS poly(3,4-ethylenedioxythiophene):polystyrenesulfonate dip coating to design piezoresistive pressure sensors. The mechanical properties of the nanosponges were tuned by introducing citric acid (CA) as a co-cross-linker, varying its content from 0% to 18% relative to the moles of primary amines of bPEI. The resulting devices functioned effectively as pressure sensors, with the best performance achieved at 3% CA. This configuration operated reliably up to 200 kPa and reached a sensitivity of 1.96 × 10–3 mA·kPa–1. These findings confirm the promising performance of cellulose-based nanosponges and pave the way for their integration into lightweight and environmentally friendly pressure sensors.