Unified Bladder Actuation System Aids Efficient Voiding

An integrated sensing-actuation device can improve the performance of underactive bladders, according to a new study.

Developed by researchers at the National University of Singapore (NUS; Singapore), the University of Tokyo (Japan), and other institutions, the novel bladder system integrates a soft, thin capacitive sensor with a shape memory alloy (SMA) based actuator in order to create a high-performance, closed-loop configuration capable of continuous bladder volume detection and voiding. The SMA actuator contains a spring element that keeps a sensor in contact with the surface of the bladder at all times for precise volume detection.


In animal studies, the system attained a highly desirable voiding target of 71-100% of a rat’s bladder with a volume sensitivity of 0.7 μF/liter. The high sensitivity of the sensor during both the storage and voiding phases is the result of its wrinkled structure, which operates similar to bladder muscle receptors with dual functionality of normal and stretching force sensation. For comparison, current implantable treatment options can only sense the fullness of the bladder, and only empty it up to 43%. The study was published on May 1, 2020, in Science Advances.

“Our solution integrates sensing-actuation elements that are bladder compatible but do not interfere with one another, achieving real-time bladder management,” said lead author Faezeh Arab Hassani, PhD, of NUS. “The bladder system can be adjusted to the user's bladder size to ensure optimal operation. The ideal scenario would be to integrate the device with a mobile application, which can retrieve and process the sensor data to allow the user to trigger voiding at will.”

Bladder volume measurement is a well-established metric used in the diagnosis and treatment of a wide range of medical conditions. It is a critical component of comprehensive catheter-associated urinary tract infections (CAUTI) prevention programs, an area of intense focus for hospitals as a result of U.S. Medicare penalties for hospitals with high rates.

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National University of Singapore
University of Tokyo