A Damage-Mapping, Self-Healing Electronic Skin for Surgical Simulation Training

Modern facilities for surgical education make use of inanimate models to simulate surgical tasks. Such models provide trainees with the opportunity to practice and receive feedback on the procedural and motor skills required to perform complex surgeries with expert-level competency. Existing models for surgical simulation rely heavily upon thermoset polymers such as silicones or hydrogels, which deteriorate after single or repeated use. Such disposable models are expensive—especially those with physically realistic properties—and incur a prohibitive cost for training programs, limiting opportunities for students to practice with high fidelity models. Moreover, evaluating the performance of trainees on surgical tasks is difficult and requires direct observation by an expert or the use of motion tracking software. There is a need to develop surgical simulation models with realistic physical properties and functional capabilities mimicking that of living tissue including, i) the ability to heal from damage, and ii) the ability to sense and transduce mechanical stimuli including forces, pressures, rates and depths of incisions and punctures. Over the past decade, advances in the science of dynamic polymeric materials (<i>i.e.,</i> polymers that are cross-linked with reversible bonds, such as hydrogen bonds) have enabled the molecular design and device integration of stretchable, conductive, self-healing composites. We have recently reported a strategy for improving the functional self-healing efficacy of multi-layer laminate composites through the molecular design of a pair of dynamic polymers with immiscible polymer backbones (poly(dimethylsiloxane) and poly(propyleneglycol)) but identical dynamic bonding units (a mixture of bisurea-based hydrogen bonding units). These polymers have a strong, adhesive but thermodynamically restricted interface, which results in an autonomous alignment and healing phenomenon, whereby polymer chains directionally diffuse to minimize the interfacial free energy when multi-layered stacks are damaged and misaligned. In this presentation, I will discuss our current efforts building upon this work towards the design of a damage-mapping electronic skin capable of sensing processes such as punctures with needles, scalpels, or sutures--and self-healing to undergo many operational cycles. We have developed a scalable compositing, compression-molding, and layer-based assembly process for fabricating multi-layer soft electronic films. We have implemented a voltage-based sensing mechanism for mapping the location and depth of needle punctures and surgical incisions. Finally, we demonstrate how these electronic skins can be integrated with surgical simulation technology, including rolling the films into vein-like tubes capable of sensing needle punctures for intravenous access training. Overall, we propose that there are many opportunities for bio-mimetic functional materials and device design within surgical simulation technology, including hybrid self-healing hydrogel-elastomer devices.