Stretchable and multifunctional strain sensors based on 3D graphene foams for active and adaptive tactile imaging

The highly developed flexible electronics puts forward higher requirements for the stretchable strain sensors with excellent multiple performances. Herein, a simple and economical fabrication strategy is adopted to obtain a new strain sensor based on Ecoflex rubbers, three-dimensional (3D) graphene foams (GrF) and modified silicone rubber (MSR). The device possesses high stretchability (tolerable strain up to 100%) with a variety of capabilities, such as pressure and strain sensing, strain visualization and strain-controlled heating. The GrF with excellent electrical property and MSR with ideal mechanical property endow the sensor with a wide sensing range (up to 100% strain and 66 kPa stress), high sensitivity (gauge factor of 584.2 within the strain range of 80%-100% and sensitivity of 0.183 kPa(-1) in 5-10 kPa) and long cycle life (more than 10,000 cycles) for pressure/strain sensing. In addition, the temperature of the device can be increased 35 degrees C in 5 min under 5 V. Based on this, the deformation is visible to the naked eyes by the color conversion of thermochromic MSR. The soft and reversible strain sensor can be served as the electronic skin (e-skin) for real-time and high accuracy detecting of electrophysiological stimuli, a wearable heater for thermotherapy or body warming and even intelligent visual-touch panel.