1. Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA.
2. Electrical and Computer Engineering Department, Georgia Institute of Technology, Atlanta, GA 30332, USA.
3. School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
4. Institute for Electronics and Nanotechnology, Georgia Institute of Technology, Atlanta, GA 30332, USA.