1. Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois
2. Division of Electrical and Computer Engineering, Louisiana State University, Baton Rouge, Louisiana
3. Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois
4. Royole Corporation, Fremont, California
5. Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois