1. Department of Biomedical EngineeringSchool of MedicineTsinghua University Beijing 100084 China
2. Department of Mechanical EngineeringBiomanufacturing and Rapid Forming Technology Key Laboratory of BeijingTsinghua University Beijing 100084 China
3. Key Laboratory of CryogenicsTechnical Institute of Physics and ChemistryChinese Academy of Sciences Beijing 100190 China