A highly stretchable and breathable polyurethane fibrous membrane sensor for human motion monitoring and voice signal recognition

Flexible wearable electronic devices are important in modern medical equipment and health detection, but the preparation of a flexible sensor with a high elasticity and breathability remains challenging. We prepared a flexible stretchable fibrous sensor by using a simple manufacturing process. The sensor had a high sensitivity, good stability, wide pressure test range, high tensile resistance, and antioxygenic property and was breathable. The sensor was used to monitor voice signals, by establishing a voice database model and constructing a voice signal processor to recognize the voice signal, which can be applied for speech recognition and rehabilitation training for those with damaged vocal cords. Based on centrifugal electrospinning technology, the polyurethane (PU) fibrous membrane was used as a sensor substrate, and multi-walled carbon nanotubes (MWCNTs) were loaded on the PU fibrous membrane by a cross tensile loading method. Scanning electron microscopy images showed that the MWCNTs and PU fibers formed a dense conductive network. The excellent conductivity provided the MWCNTs/PU stretchable fibrous membrane sensor with a low resistance of ∼800 Ω, a high elongation at break of 272 %, wide response test ranges from 0 % to 203 %, a sensitivity of up to 4177 at a strain of 190 %, and response and recovery times of 94.34 and 94.36 ms, respectively. The sensor had a mechanical durability (multicycle test of 10,000 cycles) and an excellent water vapor transmission rate (WVTR). This excellent performance ensures that the sensor can be used as a wearable device to monitor motion of various parts of the human body.