1. Department of Chemical Engineering and Koch Institute for Integrative Cancer Research Massachusetts Institute of Technology Cambridge MA 02139 USA
2. Department of Mechanical Engineering University of Utah Salt Lake City UT 84112 USA
3. Boston University School of Medicine 72 E Concord St Boston MA 02118 USA
4. Charles Stark Draper Laboratory Cambridge MA 02139 USA
5. Institute for Medical Engineering and Science Massachusetts Institute of Technology Cambridge MA 02139 USA
6. Division of Gastroenterology Brigham and Women's Hospital Harvard Medical School Boston MA 02115 USA
7. Department of Mechanical Engineering Massachusetts Institute of Technology Cambridge MA 02139 USA