11/15/2021
By Sokny Long

The University of Massachusetts Lowell, Department of Mechanical Engineering, invites you to attend amMaster’s thesis, defense by Lucas Hansen on “Direct Ink Writing of Self-Healing Elastomers for the Manufacture of Reusable Medical Patient Simulators.”

Master’s Candidate: Lucas Hansen
Defense Date: Tuesday, Nov. 23, 2021
Time: 2 to 4 p.m. EST
Location: This will be a virtual defense via Zoom. Those interested in attending should contact the student, lucas_hansen@student.uml.edu, and committee advisor, christopher_hansen@uml.edu, at least 24 hours prior to the defense to request access to the meeting.

Committee Chair (Advisor):
Christopher Hansen, Ph.D., Chair and Associate Professor, Mechanical Engineering, UMass Lowell

Committee Members:

  • Brad Pindzola, Ph.D., Senior Scientist, Triton Systems Inc.
  • Lawrence Thompson, Ph.D., Associate Teaching Professor, Mechanical Engineering, UMass Lowell
  • Alessandro Sabato, Ph.D., Assistant Professor, Mechanical Engineering, UMass Lowell

Abstract:

Medical patient simulators are training tools used by healthcare professionals, students, and soldiers to gain much needed experience to confidently perform medical procedures. These realistic simulators teach personnel to perform a variety of tasks, from bandaging of small wounds to invasive lifesaving procedures. By providing a high-fidelity training experience, students learn to use proper technique and force to successfully complete the intended medical operation. However, previously used training simulators supply a degraded teaching experience as tissue simulants age and exhibit material loss and/or wear. Due to this, costly simulators require frequent replacement or repair to maintain highly effective training opportunities. To alleviate this issue, self-healing materials provide autonomous damage repair to ensure high-fidelity training opportunities are presented for each trainee.

The research presented in this thesis aims to utilize a Direct Ink Write (DIW) additive manufacturing technique to prototype a self-healing medical training simulator. The printed inks consist of self-healing Polydimethylsiloxane (PDMS) elastomer formulations used to emulate three human tissues: skin, muscle, and pleura. To effectively select PDMS formulations mechanical characterization of the developed elastomers is compared to literature data of human tissues and commercially available simulants. The intrinsic self-healing of these materials enables a reproducible training experience as the tissues are repaired autonomously between training events.

To create DIW printable ink, volatile solvents were used to dissolve the candidate PDMS elastomers to achieve desired viscoelastic properties. Ink formulations were then printed, and the solvent evaporated to restore mechanical properties. Selection of solvents was performed using Hansen Solubility Parameters to estimate polymer-solvent interaction. By conducting rheological studies, solvent content was optimized to reduce the needed solvent amount, which improved the manufacturing process by reducing the required drying time of PDMS printed structures. Using DIW and an optimized material system, a successful simulator module was manufactured.

All interested students and faculty members are invited to attend the online defense via remote access.