1. Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
2. Robotics Institute, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
3. Department of Biomedical Engineering, University of California, Davis, Davis, CA 95616, USA.
4. Departments of Biological Sciences, Computational Biology, and Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.