Tough and self-healing linear polydimethylsiloxane elastomer with multiple hydrogen bonds for high-performance piezoresistive pressure sensor

With the rapid development of flexible electronics, the functional elastomer with excellent mechanical properties as substrate for the preparation of high-performance piezoresistive pressure sensor has become one of the frontier research hotspots. Here, a tough and self-healing linear polydimethylsiloxane (PDMS) elastomer with multiple hydrogen-bonding interactions was synthesized, and then utilized as substrate to prepare piezoresistive pressure sensor with 2-ureido-4[1H]-pyrimidinone modified carbon nanotubes (UPy-CNTs) as conductive material and salt particles as sacrificial template to construct electrical pathways and ridge-like microstructure, respectively. The obtained elastomer showed high transmittance of above 90 % and excellent mechanical properties with tensile strength of 4.23 MPa, elongation at break of 984 % and toughness of 24.83 MJ m-3. With the exchange and reconstruction of multiple hydrogen bonds, the elastomer achieved high healing efficiency of 99.1 % after healing at 80 degrees C for 24 h. In addition, the elastomer-based piezoresistive pressure sensor exhibited high sensitivity of 2.04 kPa-1, wide sensing range of 0-450 kPa, short response/recovery time of 80/100 ms and excellent sensing repeatability (8000 loading-unloading cycles). The sensor was successfully applied for detecting various human motions, including finger and knee bending, exhalation, swallowing and heart-pulse, and realized remote transmission of pressure signals with a wireless monitoring circuit. Furthermore, the sensor could restore its sensing function even after being cut into two halves, showing great potential in the fields of wearable device, health monitoring and electronic skin.