Frequency response analysis of IPMC actuators by an IR system

Ionic Polymer Metal Composites or IPMCs are emerging materials belonging to EAP class. They are of increasing interest in innovative applications due to several advantages respect to competing technologies (SMA, piezoelectric, etc.), such as the possibility to be used both as moving actuators and sensors, their lightness and the low actuation voltage. On the other hand their behaviour is not fully known and it is still subjected to deep investigations. In this perspective the development of a complete model, able to fully describe the electromechanical properties of the IPMC materials, is the aim of many research groups. To that purpose this work focuses on designing and realising a system to determine the frequency domain behaviour of an IPMC strip as actuator in order to collect information useful to model it. Here the IPMC deformation, caused by applying a voltage input signal across its thickness, is detected by using an infrared transmitter-receiver couple. This methodology is largely diffused and it is based on the acquisition of the intensity of the emitted ray after being reflected by the moving target, moreover it constitutes a low cost solution. Also a transducer is used to acquire information about the current absorbed by the device under test. For the specific application a conditioning circuitry and the software for signal processing has been designed and realised. Preliminary results show that the proposed system allows to infer a number of interesting properties of IPMC based actuators.