Urinary incontinence affects more than 300 million people worldwide. The implantation of a medical device called an artificial urinary sphincter (AUS) is the gold standard treatment when conservative and minimally invasive therapies fail. In this article, the AUSs (extra-urethral and endo-urethral sphincters) available on the market, both presented at the research level and filed as patents, are reviewed. The ability of the different solutions to effectively replace the natural sphincter are discussed, together with advantages and some possible side effects, such as tissue atrophy, overall invasiveness of the implant, and so forth. Finally, future research priorities are discussed for both endo-urethral and extra-urethral approaches considering key engineering aspects, such as materials, compression and closure mechanisms, and implantation methods, with the long-term aim of developing an effective, reliable, durable, and minimally invasive AUS capable of restoring a normal quality of life for incontinent patients.

This paper describes a biohybrid actuator consisting of a microgrooved thin film, powered by contractile, aligned skeletal muscle cells. The system was made of a thermoplastic elastomer [SBS, poly­(styrene-block-butadiene-block-styrene)]. We prepared SBS thin films with different thicknesses (0.5–11.7 μm) and Young’s moduli (46.7–68.6 MPa) to vary their flexural rigidity. The microgrooves on the SBS thin film resembled the microstructure of the extracellular matrix of muscle and facilitated the alignment and differentiation of skeletal muscle cells. Electrical stimulation was applied to self-standing biohybrid thin films to trigger their contraction, enabled by the low flexural rigidity of the SBS thin film. Finite element model simulations were also examined to predict their contractile behavior. We achieved the prediction of displacements, which were rather close to the actual values of the SBS thin film: the discrepancy was <5% on the X axis. These results pave the way for in silico prediction of the contractile capabilities of elastomeric thin films. This study highlights the potential of microgrooved SBS thin films as ultraflexible platforms for biohybrid machines.