Sustainability-Oriented Permeable and Degradable Flexible Piezoresistive Sensor for Wearable Applications

Abstract

Despite the rapid development of flexible piezoresistive pressure sensors in medical monitoring and human–computer interaction, traditional sensors fabricated with dense materials (e.g., elastomers) generally suffer from inadequate permeability and sweat trapping. This not only impairs wearing comfort but also may cause skin inflammation during long-term use. Moreover, most such sensors lack effective degradation pathways, exacerbating electronic-waste concerns, which are against the trends of sustainable development. To this end, we propose a co-electrospun approach for two precursor solutions, i.e., polydimethylsiloxane/polyamide (PDMS/PA) solution with/without carboxylated multi-walled carbon nanotube (c-MWCNT) additive. This approach produces a permeable and fully degradable nanofiber composite membrane, in which the PDMS/PA nanofibers form a nonconductive scaffold to support the conductive PDMS/PA/c-MWCNTs nanofibers with pressure-sensitive functionality. In addition to excellent and adjustable pressure-sensor performance, this device further possesses high air and moisture permeabilities (59.61 mm/s and 434.24 g·m–2·day–1) and waterproof capability, which maintains its sensing performance in the situation of human motion. The device is also fully degradable (in alcohol within 300 s) and recyclable, ensuring that the sensor conforms to the principles of sustainability-oriented process from production to disposal. Finally, we demonstrate the wide applications of this sensor in various scenarios, including human health monitoring, motion detection, and Morse code recognition.