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We demonstrate the implementation of a low-power, low-profile, varifocal liquid-crystal Fresnel lens stack suitable for tunable imaging in smart contact lenses. The lens stack consists of a high-order refractive-type liquid crystal Fresnel chamber, a voltage-controlled twisted nematic cell, a linear polarizer and a fixed offset lens. The lens stack has an aperture of 4 mm and thickness is ∼980 µm. The varifocal lens requires ∼2.5 V_RMSfor a maximum optical power change of ∼6.5 D consuming electrical power of ∼2.6 µW. The maximum RMS wavefront aberration error was 0.2 µm and the chromatic aberration was 0.008 D/nm. The average BRISQUE image quality score of the Fresnel lens was 35.23 compared to 57.23 for a curved LC lens of comparable power indicating a superior Fresnel imaging quality. 

Abstract A sliding electrolyte metal‐air microbattery driven by natural eye blinking motion is demonstrated as a source of electrical energy that can be integrated with smart contact lens platforms. The metal‐air battery (footprint 10 mm²) consists of a Mg anode and a Pt cathode, patterned on an insulating substrate and the battery electrolyte is a film of eye‐tear fluid that is periodically dragged on top of the electrodes during the natural eye‐blinking cycle, which activates the battery. When tested with an eye emulator, the open‐circuit voltage across the eye‐tear activated metal‐air battery (ETMAB) is 2.2 V. Impedance matching analysis reveals a maximum battery‐specific capacity of 3561 mAh g^–1obtained at a discharge current density of 5 mA cm^–2. The blinking activated battery exhibits the maximum generated power density of 1.3 mW cm^–2at the load of 740 Ω. The blinking ETMAB delivers eight times higher energy output and more than three times longer lifetime than achievable with static ETMAB designs.