1. Department of Civil and Environmental Engineering; Northwestern University; Evanston Illinois 60208 USA
2. Department of Mechanical Engineering Center for Engineering and Health; Skin Disease Research Center Northwestern University; Evanston Illinois 60208 USA
3. Center for Mechanics and Materials; Tsinghua University; Beijing 100084 China
4. Department of Materials Science and Engineering; Frederick Seitz Materials Research Laboratory University of Illinois at Urbana-Champaign; Urbana Illinois 61801 USA
5. State Key Lab Digital Manufacturing Equipment and Technology; Huazhong University of Science and Technology; Wuhan Hubei 430074 China
6. Department of Electrical Engineering; Ginzton Laboratory, 348 Via Pueblo Mall Stanford University; Stanford CA 94305 USA