Computational analyses for tunable solid lenses coupling polyacrylamide hydrogel electrodes

Electrically tunable lenses could change focus without motor-controlled translations of stiff lenses. Firstly, the lens system is enabled by stable polyacrylamide (PAM) hydrogel electrodes that are synthesized containing silicone oil, sodium chloride, etc. Two layers of the hydrogel are used as ionic conductors to sandwich a dielectric elastomer membrane. The maximum rupture stretch of the hydrogel was around 20 and the small strain Young’s modulus was about 0.5 kPa in experiments. Secondly, compact computational models are proposed based on the assumption of homogeneous deformation on materials, and the application of energy methods. Thickness-stretch curves of the PAM hydrogel are calculated, and the relation between electric field and stretch of a lens actuator is obtained by using the built mathematic models. Thirdly, a soft solid-body lens is described to obtain compact tunable results. The relationship between the applied voltage and the focus has also been given based on the derived equations. An increase in lens size produced larger tunable range variation. The new lens could find application in systems requiring large variations of focus with silent operation, low weight, shock tolerance, etc.