A PVDF/Au/PEN Multifunctional Flexible Human-Machine Interface for Multidimensional Sensing and Energy Harvesting for the Internet of Things
Yanning Dai, Junliang Chen, Wenbin Tian, Lijun Xu, Shuo Gao
Abstract
In the picture of the Internet of Things (IoT), smart human-machine interfaces (HMIs) play a significant role. Desired attributes for smart HMIs include multidimensional sensing, flexibility with stable responsiveness, and a long operational lifetime. To this end, in this article, we present a polyvinylidene fluoride (PVDF)/Au/polyethylene naphthalate (PEN) sandwiched architecture. Piezoelectric property of the PVDF is utilized for dynamic force sensing and touch-induced energy harvesting. A mutual capacitive based technique is employed for two-dimensional (2D) position recognition, hover distance measurement and curvature self-detection, as well as helping in compensating the static force detection shortage of the piezoelectric sensing layer. The presented HMI system achieved an overall force sensitivity at 0.07 N and capacitive resolution at 0.004 pF; and a force responsivity at 2.36 V/N in the pressure range of 1 N-30 N. In each touch event, the maximum capacitance change and the electric energy harvested in a stored capacitor are averaged at 0.016 pF and 0.038 nJ, respectively. Furthermore, interdigitated electrodes are implemented for self-detecting the device curvature. With pre-correlating of the force-voltage response under different bending degrees, a stable force detection response is realized when the shape of the device changes. The work presented in this article advances the field of human-machine interactivities.