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Proceedings Paper

Developing a polymeric sensor to monitor intracellular conditions
Author(s): Timothy C. Mudarri; Donald J. Leo; Brett C. Wood; Peter K. Shires
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Paper Abstract

Ionic electroactive polymers have been developed as mechanical sensors or actuators, taking advantage of the electromechanical coupling of the materials. This research attempts to take advantage of the chemomechanical and chemoelectrical coupling by characterizing the transient response as the polymer undergoes an ion exchange, thus using the polymer for ionic sensing. Nafion is a biocompatible material, and an implantable polymeric ion sensor which has applications in the biomedical field for bone healing research. An ion sensor and a strain gauge could determine the effects of motion allowed at the fracture site, thus improving rehabilitation procedures for bone fractures. The charge sensitivity of the material and the capacitance of the material were analyzed to determine the transient response. Both measures indicate a change when immersed in ionic salt solutions. It is demonstrated that measuring the capacitance is the best indicator of an ion exchange. Relative to a flat response in deionized water (±2%), the capacitance of the polymer exhibits an exponential decay of ~25% of its peak when placed in a salt solution. A linear correlation between the time constant of the decay and the ionic size of the exchanging ion was developed that could reasonably predict a diffusing ion. Tests using an energy dispersive spectrometer (EDS) indicate that 90% of the exchange occurs in the first 20 minutes, shown by both capacitance decay and an atomic level scan. The diffusion rate time constant was found to within 0.3% of the capacitance time constant, confirming the ability of capacitance to measure ion exchange.

Paper Details

Date Published: 27 July 2004
PDF: 12 pages
Proc. SPIE 5385, Smart Structures and Materials 2004: Electroactive Polymer Actuators and Devices (EAPAD), (27 July 2004); doi: 10.1117/12.540196
Show Author Affiliations
Timothy C. Mudarri, Virginia Polytechnic Institute and State Univ. (United States)
Donald J. Leo, Virginia Polytechnic Institute and State Univ. (United States)
Brett C. Wood, Virginia-Maryland Regional College of Veterinary Medicine (United States)
Peter K. Shires, Virginia-Maryland Regional College of Veterinary Medicine (United States)


Published in SPIE Proceedings Vol. 5385:
Smart Structures and Materials 2004: Electroactive Polymer Actuators and Devices (EAPAD)
Yoseph Bar-Cohen, Editor(s)

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