The bladder, stomach, intestines, heart, and lungs all move dynamically to achieve their purpose. A long-term implantable device that can attach onto an organ, sense its movement, and deliver current to modify the organ function would be useful in many therapeutic applications. The bladder, for example, can suffer from incomplete contractions that result in urinary retention with patients requiring catheterization. Those affected may benefit from a combination of a strain sensor and electrical stimulator to better control bladder emptying. The materials and design of such a device made from thin layer carbon nanotube (CNT) and Ecoflex 00–50 are described and demonstrate its function with in vivo feline bladders. During bench-top characterization, the resistive and capacitive sensors exhibit stability throughout 5000 stretching cycles under physiology conditions. In vivo measurements with piezoresistive devices show a high correlation between sensor resistance and volume. Stimulation driven from platinum-silicone composite electrodes successfully induce bladder contraction. A method for reliable connection and packaging of medical grade wire to the CNT device is also presented. This work is an important step toward the translation of low-durometer elastomers, stretchable CNT percolation, and platinum-silicone composite, which are ideal for large-strain bioelectric applications to sense or modulate dynamic organ states.
Bibliographical noteFunding Information:
The authors thank the NIH for their support through R21EB020811, OT2OD023873, OT2OD024907, and F31HD094480. The authors thank other members of the Peripheral Neural Engineering and Urodynamics Lab for their help with animal experiments and device testing including Alex Mundorf, Aileen Ouyang, and Eric Kennedy. The authors also acknowledge the use of the organic material processing lab area of Prof. Stephen Forrest's lab, electrochemical characterization facility of Prof. James Weiland's lab, Lurie Nanofabrication Facility (LNF) at the University of Michigan, assistance from Pilar Herrera-Fierro during the fabrication process and Beomseo Koo during the stimulation electrode characterization experiments.
All Science Journal Classification (ASJC) codes
- Biomedical Engineering
- Pharmaceutical Science