Seelay Tasmim1,Zuha Yousuf2,Farial Rahman2,Mario Romero-Ortega2,Philippe Zimmern3,Taylor Ware1
Texas A&M University1,University of Houston2,University of Texas Southwestern3
Seelay Tasmim1,Zuha Yousuf2,Farial Rahman2,Mario Romero-Ortega2,Philippe Zimmern3,Taylor Ware1
Texas A&M University1,University of Houston2,University of Texas Southwestern3
Stress Urinary Incontinence (SUI) is the involuntary leakage of urine in response to increased intra-abdominal pressure such as during coughing or sneezing. This condition affects nearly 50% of adult women. Bothersome SUI can be treated with the insertion of a synthetic or autologous sling underneath the urethra to provide needed support. A limitation of current mid-urethral slings is their fixed level of support, which cannot be modulated to adjust for voiding. Here, we report the design and fabrication of a dynamic sling based on stimuli-responsive materials such as liquid crystal elastomers or magnetic elastomers. These devices are capable of achieving shape change to adjust urethral support in response to safe stimuli such as transcutaneously delivered infrared light or magnetic field in physiologically relevant environments. A scar-tissue phantom model was developed to characterize the shape change of these devices. An <i>in vitro</i> urinary tract model was designed to study the efficacy of these stimuli-responsive devices on continence and flow. Both devices achieved significant shape change in response to IR light or magnetic field when embedded in an agar gel with 100kPa stiffness, mimicking scar tissue. Furthermore, both devices increased urethral resistance to flow, and allowed unimpeded voiding upon activation, thus affecting the sphincteric mechanism. When illuminated with IR light, the LCE-based device significantly decreased (p<0.0001) time to void 20mL of water from 5.2min ± 1min to 2min ± 0.5min. Likewise, the magnetic elastomer-based device reduced abdominal pressure by 0.51cmH<sub>2</sub>O ± 0.14cmH<sub>2</sub>O in the presence of a magnetic field, thereby reducing time to void in this in vitro model. Future work will focus on further analysis of the mechanical properties of these materials and testing for biostability. The devices will be implanted in rabbits, a viable animal model for SUI, to test the devices <i>in vivo</i>.