1 National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, United Kingdom; Department of Bioengineering, Faculty of Engineering, Imperial College London, London, United Kingdom.
2 National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, United Kingdom.
3 National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, United Kingdom; Royal Brompton Hospital, London, United Kingdom. Electronic address: g.yang@imperial.ac.uk.