1. Department of Electromechanical Engineering and Centre for Artificial Intelligence and Robotics University of Macau Macau Macau 999078 China
2. Department of Mechanical Engineering and Research Institute for Intelligent Wearable Systems The Hong Kong Polytechnic University Hong Kong 999077 China
3. State Key Laboratory of New Textile Materials and Advanced Processing Technologies Hubei Key Laboratory of Biomass Fibers and Eco‐Dyeing & Finishing Wuhan Textile University Wuhan 430200 China
4. Laboratory of Electret & its Application Hangzhou Dianzi University Hangzhou 310018 China
5. CAS Center for Excellence in Nanoscience Beijing Key Laboratory of Micro‐nano Energy and Sensor Beijing Institute of Nanoenergy and Nanosystems Chinese Academy of Sciences Beijing 100083 China
6. Berkeley Sensor and Actuator Center and Department of Mechanical Engineering University of California Berkeley CA 94720 USA