1. Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA
2. Department of Biomedical Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
3. Department of Medicine, Division of Gastrointestinal and Liver Diseases, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
4. Research and Development Unit, PhoenixBio Co., Ltd., Higashi-Hiroshima 739-0046, Japan