Ionic Polymer-Conductor Composites (IPCC) As Biomimetic Sensors, Actuators and Artificial Muscles - A Review of Recent Findings
M. Shahinpoor
Artificial Muscles Research Institute
School of Engineering & School of Medicine
University of New Mexico
Albuquerque, NM 87131
Sponsored By: Center for Materials Research and Analysis and the Department of Engineering Mechanics
Date: Tuesday, October 5, 1999
Time: 3:30 p.m.
Place: W128 Nebraska Hall
This presentation starts with an introduction to ionic-polymer-conductor composites and some mathematical modeling pertaining to them. It further discusses a number of recent findings in connection with ion-exchange polymer metal composites (IPMC) as biomimetic sensors and actuators. Strips of these composites can undergo large bending and flapping displacement if an electric field is imposed across their thickness. Thus, in this sense they are large motion actuators. Conversely by bending the composite strip, either quasi-statically or dynamically, a voltage is produced across the thickness of the strip. Thus, they are also large motion sensors. The output voltage can be calibrated for a standard size sensor and correlated to the applied loads or stresses. They can be manufactured and cut in any size and shape. In this presentation first the sensing capability of these materials is reported. The preliminary results show the existence of a linear relationship between the output voltage and the imposed displacement for almost all cases. Furthermore, the ability of these IPCC's as large motion actuators and robotic manipulators is presented. Several muscle configurations are constructed to demonstrate the capabilities of these IPCC actuators. This presentation further identifies key parameters involving the vibrational and resonance characteristics of sensors and actuators made with IPMC’s. When the applied signal frequency is varied, so does the displacement up to a point where large deformations are observed at a critical frequency called resonant frequency where maximum deformation is observed. Beyond which the actuator response is diminished. A data acquisition system was used to measure the parameters involved and record the results in real time basis. Also the load characterization of the IPCC's were measured and showed that these actuators exhibit good force to weight characteristics in the presence of low applied voltages. Finally, reported are the cryogenic properties of these muscles for potential utilization in an outer space environment of few Torrs and temperatures of the order of -140 degrees Celsius. These muscles are shown to work quite well in such harsh cryogenics environments and thus present a great potential as sensors and actuators that can operate at cryogenic temperatures.
