PVA/glycerol-based lenticular microlens array with tunable focal length depending on electric field polarization effect

Plasticized polymer gel has emerged as a new material for the fabrication of microlenses with variable focal lengths. To explore a non-toxic and non-irritating gel, we prepared a polyvinyl alcohol (PVA)/glycerol gel, which is sensitive to external direct-current (DC) voltage and exhibits a strong polarization effect upon application of an electric field. Due to the polarization effect, PVA/glycerol gel bends toward cathode like the polyelectrolyte gel. To fabricate the microlens array, PVA/glycerol gel was spin-coated on a glass substrate with diamond Indium Tin Oxides electrode. Upon application of the DC electric field, the surface of the gel membrane followed a cosine wave for creeping motion of PVA particles, hence the membrane exhibited the property of a microlens array. The experiments for measuring imaging quality and focal length of PVA/glycerol-based lenticular microlens array are performed. Our microlens array allows tunable focal length with lower driving voltage compared to the microlens array with polyvinyl chloride gel.