Modeling analysis of ionic polymer-metal composites sensors with various sizes

As one kind of typical transducers, ionic polymer-metal composite (IPMC) has the potential to be served as a flexible sensor. However, there are many factors to affect the sensing performance of IPMC during sensing process. In this work, we fabricated a series of IPMC samples with different thickness and lengths to confirm the effects of sizes (thickness and length) on the sensing ability of IPMC samples. Experimental results revealed that IPMC exhibited a better or worse bending-sensing performance as the thickness and length of IPMC sample increased, respectively. When the thickness range of IPMC changed from 50μm to 500μm, the voltage response presents an approximately linear upward trend from 0.31 to 1.54 mV. When the length range of IPMC changed from 25mm to 40mm, the voltage response presents an approximately linear downward trend from 1.35mV to 0.43 mV. To clarify the underlying mechanism in theory, we employed a physical model based on P-N-P equation to model the bending-sensing process of IPMC. Under the effects of size, the detailed parameters, such as water molecules concentration (C
W
) and cation concentration (C
I
), were observed and analyzed based on the model. The measured and calculated results of voltage response displayed a consistent trend but a large gap in terms of numerical magnitude, which is mainly attributed to the parameters difference between real materials and models.