1. Department of Mechanical Engineering, University of Colorado at Boulder, 427 UCB, 1111 Engineering Drive, Boulder, CO 80309-0427
2. Department of Mechanical Engineering, University of Colorado at Boulder, 427 UCB, 1111 Engineering Drive, Boulder, CO 80309-0427 e-mail:
3. Associate Professor Department of Mechanical Engineering, BioFrontiers Institute, Materials Science and Engineering Program, University of Colorado at Boulder, 427 UCB, 1111 Engineering Drive, Boulder, CO 80309-0427 e-mail:
4. Assistant Professor Department of Mechanical Engineering, University of Colorado at Boulder, 427 UCB, 1111 Engineering Drive, Boulder, CO 80309-0427 e-mail: