Response Characterization of Electroactive Polymers as Mechanical Sensors

Abstract

Abstract-The characterization of the dynamic response (including transfer function identification) of trilayer polypyrrole (PPy) type conducting polymer sensors is presented. The sensor was built like a cantilever beam with the free end stimulated through a mechanical lever system, which provided displacement inputs. The voltage generated and current passing between the two outer PPy layers as a result of the input was measured to model the output/input behavior of the sensors based on their experimental current/displacement and voltage/displacement frequency responses. We specifically targeted the low-frequency behavior of the sensor as it is a relatively slow system. Experimental transfer function models were generated and verified experimentally for sensors with different dimensions. The models can be used to understand the dynamic behavior and sensing ability of the polymers as mechanical sensors. The effect of the active sensor length on the voltage and current outputs has demonstrated that the shorter is the sensor length, the higher are the voltage output and the current passed for the same mechanical input. Also, their current and voltage responses under an impulse displacement stimulus were experimentally measured to show their dynamic sensing response and to estimate the current and voltage sensing bandwidths. Further, an energy balance method has been proposed to estimate the sensor output. Based on the novel experimental and analytical results, the contribution of this study is the first comprehensive investigation into the response analysis and characterization of the PPy-type conducting polymers as mechanical sensors, to the best of authors' knowledge.

Numerical Simulation of Mechanical Sensors Using Conducting Polymers

“…Alici et al (2) (6) shows that one conducting polymer can operate as both of mechanical actuators and sensors like artificial muscle. When the conducting polymer sensors are deformed, they generate electric potential corresponding to the magnitude of the stimulation, conversely to the process of the actuation.…”

“…The problem is, as shown in Fig. 1 (2) (6) , the non-invertible relation that the generated electric potential of the sensation is very much smaller than the electric potential of the actuation with respect to the same displacement and structure.…”

“…The mechanical sensors of the conducting polymers have very thin thickness comparing length and width, e.g. 0.17mm thickness and 10mm length (2)(3)(5) (6) . On the length scale of the sensor, the researches (1)(2)(3)(5) (6) have investigated the macroscopic properties of the conducting polymers, but the quantitative measurements over the microscale thickness, which are the evidences for the validation of hypotheses, have not been obtained, so the simulation is needed to help the prediction and validation.…”

“…In the experiments of Wu et al (5) and Alici et al (6) , the electricity of the conducting polymer sensor is induced during transient responses. However, the simulation model for the transient behaviors has not been established until now.…”

Dynamometer Power Output Measurements of Miniature Piezoelectric Actuators

“…In this paper, we present a dynamometer for measuring real ac power delivery from a 10-mg piezoelectric actuator. AC characterization of actuators and sensors [3] is generally done in the sinusoidal steady state. Piezoelectric bending actuators have been utilized in many areas of robotics, such as to flap the wings of a microair vehicle (in [26], shown in Fig.…”