1. Department of Materials, Department of Bioengineering and Institute for Biomedical Engineering, Imperial College London, London SW7 2AZ, U.K.
2. Mologic Ltd., Bedford Technology Park, Thurleigh, Bedfordshire MK44 2YP, U.K.
3. Hepatology and Gastroenterology Section, Faculty of Medicine, St Mary’s Hospital Campus, Imperial College London, London W2 1NY, U.K.