Nowadays, wearable devices for physiological-biomechanical systems monitoring allow individuals to manage their own health, and professionals to receive quickly information about their patients' conditions. Sensors are essential components in wearable electronics, enabling the key functions that make devices be worn. In particular, advances with pressure sensors heavily affect wearable technology.
The project is aimed at developing novel extremely soft, lightweight proof-of-concept piezoresistive pressure sensors characterized by a high sensitivity in a wide pressure range (10 Pa - 100 kPa). It is focused on the experimental characterization and electro-mechanical modelling of open cell, sponge-like, low density materials with pressure dependent conducting properties and fabricated through a cost effective approach. A flexible porous 3D silicon rubber skeleton will be obtained by infiltrating with EcoFlex a template formed by polymeric micro beads that will be dissolved in acetone. The elastomeric foam, after porogens leaching will be dipped in a colloidal suspension of multilayer-graphene nanoplatelets (MLG) and ethanol. The assisted evaporation of the solvent leaves a thin layer of MLG over the pores' surface: the final material is a piezoresistive, extremely soft and free-standing foam of a novel type, characterized by a high compression sensing capability attributable to the rearrangement of the conducting nanofiller network during compression loading. The electromechanical performances of the novel sensors will be experimentally assessed. New theoretical models able to predict the resistance of the materials as a function of the MLG characteristics and weight fractions, porosity and applied compression will be developed and experimentally validated. A proof-of-concept pressure sensor for blood pressure and heart rate real-time monitoring will be finally fabricated at laboratory level, calibrated and tested.