1. Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
2. Department of Bioengineering, University of Washington, Seattle, WA, USA
3. Department of Periodontics, University of Washington, Seattle, WA, USA
4. Department of Oral Health Sciences, University of Washington, Seattle, WA, USA
5. Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA