1. School of Engineering The University of British Columbia Kelowna BC V1V 1V7 Canada
2. Department of Mechanical and Manufacturing Engineering University of Calgary Calgary Alberta T2N 1N4 Canada
3. Department of Mechanical Engineering The University of British Columbia Vancouver BC V6T 1Z4 Canada
4. Division of Engineering in Medicine Department of Medicine Harvard Medical School Brigham and Women's Hospital Cambridge MA 02139 USA