1 Department of Mechanical Engineering, The University of Hong Kong, Hong Kong; Advanced Biomedical Instrumentation Centre, Hong Kong Science Park, Shatin, New Territories, Hong Kong.
2 Department of Mechanical Engineering, The University of Hong Kong, Hong Kong.
3 Department of Mechanical Engineering, The University of Hong Kong, Hong Kong; Advanced Biomedical Instrumentation Centre, Hong Kong Science Park, Shatin, New Territories, Hong Kong. Electronic address: ylin@hku.hk.