Toward Self-Control Systems for Neurogenic Underactive Bladder: A Triboelectric Nanogenerator Sensor Integrated with a Bistable Micro-Actuator

Abstract

Aging, neurologic diseases, and diabetes are a few risk factors that may lead to underactive bladder (UAB) syndrome. Despite all of the serious consequences of UAB, current solutions, the most common being ureteric catheterization, are all accompanied by serious shortcomings. The necessity of multiple catheterizations per day for a physically able patient not only reduces the quality of life with constant discomfort and pain but also can end up causing serious complications. Here, we present a bistable actuator to empty the bladder by incorporating shape memory alloy components integrated on flexible polyvinyl chloride sheets. The introduction of two compression and restoration phases for the actuator allows for repeated actuation for a more complete voiding of the bladder. The proposed actuator exhibits one of the highest reported voiding percentages of up to 78% of the bladder volume in an anesthetized rat after only 20 s of actuation. This amount of voiding is comparable to the common catheterization method, and its one time implantation onto the bladder rectifies the drawbacks of multiple catheterizations per day. Furthermore, the scaling of the device for animal models larger than rats can be easily achieved by adjusting the number of nitinol springs. For neurogenic UAB patients with degraded nerve function as well as degenerated detrusor muscle, we integrate a flexible triboelectric nanogenerator sensor with the actuator to detect the fullness of the bladder. The sensitivity of this sensor to the filling status of the bladder shows its capability for defining a self-control system in the future that would allow autonomous micturition.

Recent Advances in Triboelectric Nanogenerator‐Based Health Monitoring

“…Nanogenerators are promising to address such challenges in ways of serving as self‐powered health sensors or acting as the power source of the self‐powered health sensing system. TENGs have been applied for implantable heath monitors in both ways . Ma et al reported an implantable TENG that can monitor multiple physiological and pathological signs in real time ( Figure a–c) .…”

The recent advances in self‐powered medical information sensors

“…In addition to aforementioned medical information related to respiration, cardiovascular system, body temperature, and perspiration, the self‐powered sensors based on or powered by energy harvesters were also demonstrated to show capacity in detecting other medical signals deriving from bladder, eye ball, stomach, and brain …”

Controlling Surface Charge Generated by Contact Electrification: Strategies and Applications

“…Increasing surface charge generated by contact electrification is also useful for sensing of human activity such as bodily motion, bending or touching (via sensing of pressure), and physiological signals by wearable or implantable devices . One specific application involves an ultrasensitive pulse sensor based on a flexible TENG (Figure d) .…”