1. Department of Bioengineering, University of California San Diego, La Jolla, California, USA.
2. Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, California, USA.
3. Department of Orthopedic Surgery, University of California San Diego, La Jolla, California, USA.
4. Department of NanoEngineering, University of California San Diego, La Jolla, California, USA.