1. Innovative Centre for Flexible Devices (iFLEX), Max Planck−NTU Joint Lab for Artificial Senses, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
2. Key Laboratory of Colloid and Interface Chemistry of the Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China
3. Advanced Robotics and Intelligent Control Centre, Singapore Polytechnic, 500 Dover Road, Singapore 139651, Singapore
4. Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 2 Fusionopolis Way, Innovis, #08-03, Singapore 138634, Singapore