1. Thayer School of Engineering, Dartmouth College, Hanover, NH 03755
2. Thayer School of Engineering, Dartmouth College, Hanover, NH 03755;
3. Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY 14627
4. Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114
5. Institute for Liver and Digestive Health, University College London, London NW3 2QG, UK
6. Thayer School of Engineering, Dartmouth College, Hanover, NH 03755 e-mail: