1. Department of Nuclear, Plasma and Radiological Engineering; University of Illinois at Urbana-Champaign; Urbana Illinois 61801 USA
2. Micro and Nano Technology Laboratory; University of Illinois at Urbana-Champaign; Urbana Illinois 61801 USA
3. Department of Physics; University of Illinois at Urbana-Champaign Urbana; Illinois 61801 USA
4. Department of Material Science and Engineering; University of Illinois at Urbana-Champaign; Urbana Illinois 61801 USA
5. Department of Electrical and Computer Engineering; University of Illinois at Urbana-Champaign Urbana; Illinois 61801 USA
6. Department of Bioengineering; University of Illinois at Urbana-Champaign; Urbana Illinois 61801 USA
7. Meso, Micro and Nano Technologies Center Lawrence Livermore National Laboratory; 7000 East Avenue, Livermore California 94550 USA
8. Department of Electrical and Computer Engineering; University of Illinois at Urbana-Champaign; Urbana Illinois 61801 USA