1. Department of Electrical and Computer Engineering and the Department of Rehabilitation Medicine, University of Washington (UW), Seattle, WA, USA
2. Department of Mechanical Engineering, NanoFAB.SDSU Research Laboratory, San Diego State University, San Diego, CA, USA
3. Department of Electrical and Computer Engineering, the Department of Rehabilitation Medicine, and the Department of Physiology and Biophysics, UW, Seattle, WA, USA