Two strategies have emerged to replace or augment the functions of damaged natural muscle: 1) use tissue engineering to grow new functional tissue or 2) engineer mechanical devices capable of reversibly changing shape. Here we focus on understanding and designing biomaterials that can function as mechanical devices and as such replace the function of damaged tissue. The goal of this proposal is to synthesize and characterize liquid crystal elastomers (LCEs) that are capable of reversible shape change in response to near IR light delivered through the skin. This project will thus enable a new class of medical devices capable of using soft actuators to deform soft tissues, like the urethral wall in women. While we envision numerous applications for these artificial muscles, we seek to evaluate the performance of LCEs to manage stress urinary incontinence. Stress urinary incontinence, incontinence related to events such as laughing, coughing, or sneezing, affects up to 50% of women, leading to a significant reduction in quality of life and annual costs of ~$32bn in the United States. Among the current surgical treatment options, the synthetic mid-urethral sling is the current standard of care. At present, the sling materials placed around the urethra are permanently fixed and do not adapt to continence needs. This static behavior is a leading contributor to complications, which occur in up to 10% of cases. Our central hypothesis is that the shape change of LCEs can be used to reversibly deform soft tissues in response to transcutaneous application of IR light. To evaluate this hypothesis, we propose two specific aims: 1) Fabricate and characterize LCEs capable of changing shape in response to transcutaneous IR-light and control actuation stress and strain in simulated physiological conditions and 2) Elucidate the effects of tissue modulus on the shape change of LCE devices and measure changes in stress leak-point pressure as a function of actuator shape in an animal incontinence model. The team includes experts in biomaterials (Ware), transcutaneously-powered devices (Romero-Ortega), and surgical treatment of incontinence (Zimmern).
This project investigates a class of materials that may be used to replace or augment the function of damaged muscle without requiring implanted electronics or batteries. These new artificial muscles may have applicability in medical devices including in the restoration of motor function or as artificial sphincters. Here we will evaluate the use of these materials to create a dynamic sling for the treatment of stress urinary incontinence, a condition that affects up to 50% of women during their lifetime and leads to significant reduction in quality of life.