Wide Range Strain Distributions on the Electrode for Highly Sensitive Flexible Tactile Sensor with Low Hysteresis

Flexible piezoresistive tactile sensors are widely used in wearable electronic devices because of their ability to detect mechanical stimuli. However, achieving high sensitivity and low hysteresis over a broad detection range remains a challenge with current piezoresistive tactile sensors. To address these obstacles, we designed elastomeric micropyramid arrays with different heights to redistribute the strain on the electrode. Furthermore, we mixed single-walled carbon nanotubes in the elastomeric micropyramids to compensate for the conductivity loss caused by random cracks in the gold film and increase the adhesion strength between the gold film (deposited on the pyramid surface) and the elastomer. Thus, the energy loss of the sensor during deformation and hysteresis (similar to 2.52%) was effectively reduced. Therefore, under the synactic effects of the percolation effect, tunnel effect, and multistage strain distribution, the as-prepared sensor exhibited a high sensitivity (1.28 x 106 kPa-1) and a broad detection range (4.51-54837.06 Pa). The sensitivity was considerably higher than those of most flexible pressure sensors with a microstructure design. As a proof of concept, the sensors were successfully applied in the fields of health monitoring and human-machine interaction.

Automated summary

In this study, elastomeric micropyramid arrays with different heights were designed to redistribute strain and address the challenges of achieving high sensitivity and low hysteresis in piezoresistive tactile sensors. Single-walled carbon nanotubes were mixed into the micropyramids to compensate for conductivity loss and increase adhesion strength. The resulting sensor exhibited high sensitivity (1.28 x 106 kPa-1) and a broad detection range (4.51-54837.06 Pa) due to the synergistic effects of percolation, tunneling, and multistage strain distribution. Successful applications in health monitoring and human-machine interaction were demonstrated.