Eye Tear Activated Mg‐Air Battery Driven by Natural Eye Blinking for Smart Contact Lenses
Erfan Pourshaban, Aishwaryadev Banerjee, Mohit U. Karkhanis, Adwait Deshpande, Chayanjit Ghosh, Hanseup Kim, Carlos H. Mastrangelo
Abstract
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 mm 2 ) 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 –1 obtained 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 –2 at 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.