Actuation of Tunable Elastomeric Pores: Resistance Measurements and Finite Element Modelling

We present a quantitative study of elastomeric nano- / micropore actuation using experiments and a finite element model. Ionic resistances have been measured for five specimens of two distinct sizes at macroscopic strains up to 0.25. Over repeated stretch cycles, resistance measurements indicate that the relaxed size of the smaller pores decreased, and that the larger pores increased in size, probably due to plasticity and viscoelasticity in the elastomeric membranes. The resistance of stretched, stress-softened pores was simulated using a hyperelastic model for the elastomer. The initial stages of stretching are complicated, probably due to wrinkles in the region immediately adjacent to the pore, but modelled and experimental resistance trends agree for macroscopic strains between 0.05 and 0.25. In this region, the decrease in resistance with strain is empirically described by an inverse power law with an exponent of 1.2. Tunable pores are of growing importance for resistive pulse sensing of nano- and microparticles, while nanoscale actuation of elastomers is increasingly being used in fluidics, optics and other fields.