Polyelectrolyte Elastomer‐Based Ionotronic Electro‐Mechano‐Optical Devices

Abstract All‐solid electrically tunable lenses outperform rigid‐body translation‐based counterparts in compactness, lightweight, and response speed. However, the large and uneven thickness of conventional lenses exerts substantial mechanical constraints and inhomogeneous deformation. Herein, smart tunable lenses are reported by coupling the optical performance of a Fresnel lens to the electro‐mechanical behaviors of a dielectric elastomer actuator. A polyelectrolyte elastomer with balanced mechanical, electrical, and optical properties is designed and synthesized as the electrode. The optimized polyelectrolyte elastomer exhibits an elastic modulus of 45 kPa, a fracture strain of > 20, and an average transmittance of 97.3% within the visible wavelength range. The Fresnel lens‐shaped polyelectrolyte elastomer has a thickness of 150 µm and a diameter of 15 mm. Subject to voltage, the polyelectrolyte elastomer deforms with the dielectric elastomer and changes its geometrical features, achieving a change in focal length of ≈31%. A finite element model is established to investigate the electro–mechano–optical coupling behaviors of the lens and obtain satisfactory agreement between simulation and experiment. The resulting lens exhibits a fast response, operates stably over 10 000 cycles, and maintains functions over 4 weeks. Ionotronic tunable Fresnel lenses provide adjustable, precise, and efficient solutions for adaptive optics systems.