Ultracompliant Carbon Nanotube Direct Bladder Device

Abstract

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 using catheterization. Those affected may benefit from a combination of strain sensor and electrical stimulator to better control bladder emptying. We describe the materials and design of such a device made from thin layer carbon nanotube (CNT) and Ecoflex 00-50 and demonstrate its function with in vivo feline bladders. During bench-top characterization, the resistive and capacitive sensors exhibited reliable output throughout 5,000 stretching cycles under physiology condition. In vivo measurement with piezoresistive device showed a high correlation between sensor resistance and volume. Stimulation driven from Pt-PDMS composite electrodes successfully induced bladder contraction. We This article is protected by copyright. All rights reserved. present method for reliable connection and packaging of medical grade wire to the CNT device. This work is an important step toward the translation of lowdurometer elastomers, stretchable CNT percolation and Pt-PDMS composite, which are ideal for large strain bioelectric applications to sense or modulate dynamic organ states.

Soft Electronics Based on Stretchable and Conductive Nanocomposites for Biomedical Applications

“…(A,ii) Reproduced with permission. [ 29 ] Copyright 2019, Wiley‐VCH GmbH. (B,i) Reproduced with permission.…”

“…The 3 mm 2 large electrodes were subsequently coated with a platinum‐silicone composite by blade coating. [ 29 ] Guo et al. used sacrificial posts of photoresist together with a 10 µm thick PDMS encapsulation to define the electrode sites.…”

“…[26] The nanocomposite conductors also face a though set of requirements related to corrosion, long-term stability and (nano)toxicity. Biocompatible nanocomposite conductors have been based on platinum microparticles, [22,27] gold-coated nanowires (NWs), [23,28] microcracked gold films, [22] carbon nanotubes (CNTs), [29] and conducting polymers. [25,30] From a fabrication perspective, it is important to tailor the processes in such a way that biocompatibility is preserved throughout the process.…”

Soft sensors for a sensing-actuation system with high bladder voiding efficiency

“…The additional stretchable property of these materials makes them suitable for tactile strain sensing applications (9,20,21). The direct integration of these strain sensors with the bladder for volume detection requires materials with a lower modulus than the bladder muscle (3,(22)(23)(24)(25)(26)(27). This property allows normal expansion and shrinkage of the bladder for muscle distention measurement during the storage (23).…”

“…For bladder elasticity matching, soft electrical stimulation actuators have been reported to void the bladder (22,23,32). These actuators consist of soft electrodes that are directly attached on the bladder surface for electrical stimulation of the muscle (22) or its related nerves (23). To avoid possible electrical stimulation of untargeted neighboring muscles or nerves, soft actuators capable of physical bladder compression have been developed (33).…”