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

Faezeh Arab Hassani*, Roshini P. Mogan, Gil G.L. Gammad, Hao Wang, Shih Cheng Yen, Nitish V. Thakor, Chengkuo Lee

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

49 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)3487-3501
Number of pages15
JournalACS Nano
Issue number4
Publication statusPublished - 24 Apr 2018

Bibliographical note

Funding Information:
*E-mail: *E-mail: *E-mail: *E-mail: ORCID Faezeh Arab Hassani: 0000-0003-4425-6289 Chengkuo Lee: 0000-0002-8886-3649 Author Contributions F. A. Hassani, H. Wang, and C. Lee: device design concept. F. A. Hassani: device modeling, fabrication, and characterization. F. A. Hassani and S.-C. Yen: experimental design and setup and in vivo test data interpretation. R. O. Mogan and G. G. L. Gammad: animal surgeries. F. A. Hassani: in vivo test setup and device implantation on bladder. S.-C. Yen, N. V. Thakor, and C. Lee: principal investigators, study design, data interpretation. All authors have given approval to the final version of the manuscript. Funding The authors would like to acknowledge financial support from following research grants: NRF-CRP10-2012-01 ‘Peripheral Nerve Prostheses: A Paradigm Shift in Restoring Dexterous Limb Function’ and NRF-CRP8-2011-01 ‘Self-powered body sensor for disease management and prevention-orientated healthcare’ from the National Research Foundation (NRF), Singapore, Faculty Research Committee (FRC) grant-R-263-000-B56-112 ‘Thermoelectric power generator (TEG) based self-powered ECG plaster− System integration (Part 3)’ at the National University of Singapore, Singapore, and HIFES Seed Funding-2017-01 grant R-263-501-012-133 ‘Hybrid integration of flexible power source and pressure sensors’ at the National University of Singapore, Singapore. Notes The authors declare no competing financial interest.

Publisher Copyright:
© 2018 American Chemical Society.

Copyright 2018 Elsevier B.V., All rights reserved.


  • bistable
  • flexible
  • myogenic and neurogenic underactive bladder
  • restoration-compression
  • shape memory alloy actuator
  • triboelectric nanogenerator sensor


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