Facile Preparation of Carbon Nanotube-Based Skin-Like Pressure Sensors

Abstract

Flexible sensors have garnered significant interest for their potential to monitor human activities and provide valuable feedback for healthcare purposes. Single-walled carbon nanotubes (SWNTs) are promising materials for these applications but suffer from issues of poor purity and solubility. Dispersing SWNTs with conjugated polymers (CPs) enhances solution processability, yet the polymer sidechains can insulate the SWNTs, limiting the sensor's operating voltage. This challenge can be addressed by incorporating a self-immolative linker into the sidechain of a poly(fluorene-co-phenylene) polymer, facilitating the fast and clean removal of sidechains and enabling the generation of high-conductivity SWNT materials. In this work, the integration of this advanced material with polydimethylsiloxane (PDMS) to create skin-like ultra-wrinkled film surfaces in a simple, cost-effective, and highly reproducible manner is demonstrated. The sensors exhibit remarkable sensitivity (1,655 kPa⁻¹) across a wide dynamic range (0.003–70.1 kPa, R2 = 0.9931) when the wrinkle axis is aligned perpendicularly to the interdigitated electrode fingers. The sensor shows an almost instantaneous pressure response and maintains excellent stability. This sensor can monitor various human motions, from low-intensity activities such as breathing, pulse, and voice vibrations to high-intensity actions like walking and jumping, highlighting their potential use in wearable human health monitoring systems.