As soft robots decrease in size for applications such as in implantable devices, minimally invasive surgical tools, and wearable technologies, the key features to achieving environmental control are material chemistry, manufacturing methods, embedded sensors and surface topography. While the field of medical device design has made tremendous progress in recent decades, devices at the biotic abiotic interface continue to be plagued by the body’s immune response. The field of soft robotics uses low modulus materials that compliance match surrounding tissues to help address this issue. Although durable and elastic, traditional synthetic polymers often lead to fibrosis. To advance the use of soft robotics in medical devices, new materials must be explored to read and write to the local microenvironment. In this presentation, we will highlight work across multiple spatial scales to engineer hydrogel actuators for in vivo applications as implantable devices and surgical tools. We hypothesize that hydrogel soft robotic actuators hold promise for implantable medical devices by providing physiologically relevant chemical cues. We start by detailing development and characterization of centimeter scale crosslinked gelatin actuators. Tendon actuated grippers made from natural materials can be designed to match a wide range of tissues and resist fatigue in simulated in vivo environments. We next describe our results in modifying hydrogel materials to sense and respond to microenvironmental cues that have allowed us to create cell-scale microgrippers. We show 3D printed microgrippers based on traditional MEMs designs as well as non-planar, bioinspired architectures. Using multiphoton lithography, we fabricate multimaterial actuators that incorporate inert skeletal components with hydrogel actuators. We evaluate the response time, accuracy and cyclability of grippers that use temperature and pH responsive hydrogels. Following this optimization, we designed microgrippers that incorporate a photothermal transducer within a thermally responsive gel actuator fabricated on the tip of a 200-micron diameter core fiber. By incorporating 3D printed micro-optics, we show that gripper components can be actuated individually via site-specific transduction. This work provides a foundation to integrate stimuli responsive mechanical functions within hydrogel based medical device designs for improved function and reliability in vivo.

Design and characterization of engineered biomaterials as soft actuators for In Vivo applications

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.