An Instrumented Urethral Catheter with a Distributed Array of Iontronic Force Sensors

Ye Zhang, Mahdi Ahmadi, Gerald Timm, Serdar Sezen, Rajesh Rajamani

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


This paper develops a novel instrumented urethral catheter with an array of force sensors for measuring the distributed pressure in a human urethra. The catheter and integrated portions of the force sensors are fabricated by the use of 3D printing using a combination of both soft and hard polymer substrates. Other portions of the force sensors consisting of electrodes and electrolytes are fabricated separately and assembled on top of the 3D-printed catheter to create a soft flexible device. The force sensors use a novel supercapacitive (iontronic) sensing mechanism in which the contact area between a pair of electrodes and a paper-based electrolyte changes in response to force. This provides a highly sensitive measure of force that is immune to parasitic noise from liquids. The developed catheter is tested using a force calibration test rig, a cuff-based pressure application device, an extracted bladder and urethra from a sheep and by dipping inside a beaker of water. The force sensors are found to have a sensitivity of 30–50 nF/N, which is 1000 times larger than that of traditional capacitive force sensors. They exhibit negligible capacitance change when dipped completely in water. The pressure cuff tests and the extracted sheep tissue tests also verify the ability of the sensor array to work reliably in providing distributed force measurements. The developed catheter could help diagnose ailments related to urinary incontinence and inadequate urethral closure pressure.

Original languageEnglish (US)
Pages (from-to)149-161
Number of pages13
JournalAnnals of Biomedical Engineering
Issue number1
StatePublished - May 6 2020

Bibliographical note

Funding Information:
This work was supported in part by Mn-Reach, a NIH research Evaluation and Commercialization Hub, and by the National Science Foundation through Grant EFRI 1830958.

Publisher Copyright:
© 2020, Biomedical Engineering Society.


  • Catheter pressure sensors
  • In vivo force sensors
  • Instrumented catheter
  • Iontronic sensors
  • Parasitic capacitance
  • Supercapacitive sensors
  • Urethral sensors


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