Highly Sensitive Piezoelectric E-Skin Design Based on Electromechanical Coupling Concept

Stretchable electronic skin (e-skin) paves the way for applications that exceed the scope of intrinsic rigid devices and hard-to-stretch sensors. The broad application range of flexible e-skins benefits from device architectures that can simultaneously provide mechanical flexibility and superior sensitivity. Classic fractal design provides a simple architecture to achieve the desired flexibility through structural design for improved wear comfort, but at the expense of sensor sensitivity. In this study, the proposed method addresses the trade-off between stretchability and sensitivity in fractal design. A high-sensitivity e-skin is obtained by eliminating the effect of negative charge on the output by applying the concept of electromechanical coupling. This concept for designing e-skins with high sensitivity is validated through the delicate patterning of hard-to-stretch functional materials. Further, human speech signals are acquired through the integration of e-skin with signal processing circuits, and speech pattern recognition is realized using machine learning. The stretchable e-skin with an enhanced gauge factor illustrates the wider application of this concept for improving the sensitivity of stretchable electronic functional materials.