1. Department of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY 14850, USA.
2. Facebook Reality Labs, Redmond, WA 98052, USA.
3. Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14850, USA.
4. Center for Micro-Biorobotics, Istituto Italiano di Technologia, Pontedera, PI 56025 Pisa, Italy.