1. Department of Electrical and Computer Engineering, University of Illinois, Chicago, IL 60607, USA
2. Department of Bioengineering, University of Illinois, Chicago, IL 60607, USA
3. Department of Chemical Engineering and Materials Science, University of California, Irvine, CA 92697, USA
4. Department of Electrical Engineering and Computer Science, University of California, Irvine, CA 92697, USA
5. Department of Physics, University of Illinois, Chicago, IL 60607, USA