1. Department of Materials Science and Engineering, Beckman Institute for Advanced Science and Technology, and Frederick Seitz Materials Research Laboratory University of Illinois at Urbana‐Champaign Urbana IL 61801 USA
2. Department of Electrical and Computer Engineering University of Illinois at Urbana‐Champaign Urbana IL 61801 USA
3. Department of Civil and Environmental Engineering Department of Mechanical Engineering Northwestern University Evanston IL 60208 USA
4. Center for Engineering and Health Skin Disease Research Center Northwestern University Evanston IL 60208 USA
5. Center for Mechanics and Materials Tsinghua University Beijing 100084 China
6. Department of Materials Science and Engineering Beckman Institute for Advanced Science and Technology and Frederick Seitz Materials Research Laboratory University of Illinois at Urbana‐Champaign Urbana IL 61801 USA