BME PhD Preliminary Exam Announcement for Ángel G. Enriquez (H. Lee, advisor) Everyone is invited to attend the public presentation beginning at 3:00pm. Thesis Title: Magnetic actuators for smart functionality in biomedical devices Date: April 27th Time: 3:00 PM Location: MRGN 129 Advisory Committee: Hyowon Lee, Chair; Chi Hwan Lee; Luis Solorio; Daniel H. Sahlein Abstract: Magnetism provides numerous advantages to actuating systems, specifically for biomedical applications. The untethered transfer of energy and scalability of magnetic actuators enables functionality to an otherwise passive system. For example, the wireless magnetic actuation can turn static 2D and 3D cell cultures into a more physiologically-relevant dynamic environment while limiting contamination. Moreover, indwelling catheters and implantable sensors are typically stationary devices that are notorious for their short lifespan when implanting into the body due to immune responses. Magnetic microactuators may be used for wireless actuation for in situ removal of biological materials accumulated on chronically implanted devices. In this dissertation, I will demonstrate examples of novel biomedical microdevices enabled by magnetic actuation for added functional benefits. First, I will describe a soft polymer magnetic actuator that can facilitate the study of a physiologically relevant cell culturing system. By cyclically stretching an extracellular matrix protein in a 3D cell culture, this system can elucidate the process by which breast cancer cells respond to a dynamic environment in the lungs. The fibrillar fibronectin suspended across the body of the magnetic actuator provides a matrix representative of early metastasis for 3D cell culture that has not yet been recapitulated in vitro until now. Our findings suggest that this dynamic environment leads to significant matrix degradation in breast cancer cell lines with metastatic potential. Our results demonstrate a clear suppressive cellular response due to cyclic stretching that has implications for a mechanical role in the dormancy and reactivation of disseminated breast cancer cells to macrometastases. As a second application, I will demonstrate the use of magnetic microactuators to remove biofouling on an implantable biosensor in order to prolong its functionality. The results of our work suggest that the motion of the actuator on the sensor surface can maintain biosensor signal integrity and prevents the downstream effects of the foreign body response. In the future, I plan to evaluate the performance of the self-clearing biosensor in vivo to demonstrate chronic and reliable sensor functionality.