Flexible pressure sensors tuned by interface structure design – Numerical and experimental study

Flexible pressure sensors have aroused wide research interest because they can be conformably attached to various irregular surfaces. At the present, it is still challenge to adjust the sensitivity and response range of resistive pressure sensors for practical uses. To uncover the insights of sensing ability, the surface textures are designed with pyramids of different sizes and density distributions for finite element analyses and experimental studies. The results show that the initial contact area has substantial effects on the sensitivity while the structure dimensions are proportional to the ability of sensing range. Using these design strategies, the sensor with the highest sensitivity (18.4 kPa-1) is constructed by the structures with gradient height distribution crossing the sensing area. The obtained sensitivity is among the highest performed resistive pressure sensors in the category. The sensitivity and response range of the sensor can be adjusted by changing the density and size of the pyramids. In addition, the flexible sensor based on PDMS elastomer and MWCNTs/PDMS conductor also reacts fast (< 200 ms) when sensed a pressure change. Furthermore, the flexible resistive pressure sensors are highly reproducible and stable through the 5000 cycles repeated pressure stress without the sign of degradation. In application front, the sensors can quickly and accurately identify tactile signals and haptic signals at different frequencies under different pressures. The pressure sensors applied this design strategy are suitable for wearable electronics in human health care with the biocompatible materials with the flexible and comfortable natures.