Zhengpeng Wan1, Roger D Kamm2,3. 1. Department of Biological Engineering, Massachusetts Institutes of Technology, Cambridge, MA, USA. 2. Department of Biological Engineering, Massachusetts Institutes of Technology, Cambridge, MA, USA. rdkamm@mit.edu. 3. Department of Mechanical Engineering, Massachusetts Institutes of Technology, Cambridge, MA, USA. rdkamm@mit.edu.