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Abstract On‐the‐eye microsystems such as smart contacts for vision correction, health monitoring, drug delivery, and displaying information represent a new emerging class of low‐profile (≤ 1 mm) wireless microsystems that conform to the curvature of the eyeball surface. The implementation of suitable low‐profile power sources for eye‐based microsystems on curved substrates is a major technical challenge addressed in this paper. The fabrication and characterization of a hybrid energy generation unit composed of a flexible silicon solar cell and eye‐blinking activated Mg–O₂metal–air harvester capable of sustainably supplying electrical power to smart ocular devices are reported. The encapsulated photovoltaic device provides a DC output with a power density of 42.4 µW cm⁻²and 2.5 mW cm⁻²under indoor and outdoor lighting conditions, respectively. The eye‐blinking activated Mg–air harvester delivers pulsed power output with a maximum power density of 1.3 mW cm⁻². A power management circuit with an integrated 11 mF supercapacitor is used to convert the harvesters’ pulsed voltages to DC, boost up the voltages, and continuously deliver ≈150 µW at a stable 3.3 V DC output. Uniquely, in contrast to wireless power transfer, the power pack continuously generates electric power and does not require any type of external accessories for operation. 

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. 

We propose an artificial iris to tackle sensitivity caused by photophobia. This artificial iris is made with a twisted nematic cell sandwiched between two linear polarizers. The light attenuation performance of a commercial TNC was compared with TNCs made for smart contact lenses. 

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. 

We report the theory, construction, and testing of a flexible ocular, on-the-eye microsystem used for ultra-low power object distance sensing suitable for smart adaptive contact lenses. The microsystem determines object distance by vergence angle triangulation. Vergence angle is determined from passive measurements of the earth’s magnetic field at each eye. Vergence measurements were performed every 5-degree interval over 35 degrees in total for each eye to accommodate the entire human visual range. Vergence angle measurements had an RMS error of 1.74 degrees and a distance ranging RMS error of 14.04 mm. The energy requirement per magnetic field measurement was estimated to be approximately 2 μJ per eye. 

We demonstrate fabrication of tunable flexible refractive Fresnel liquid-crystal lens using PET for Smart Contact Lens System. We show focus tunability of 1.9D at 1.1V_RMSusing voltage and pulse width modulation lens tuning techniques. 

This paper reports the microfabrication of a Galinstan-based flexible coil on a contact lens and its preliminary use for wireless power transfer onto a smart contact lens. The Galinstan-based coil provides accommodation against physical deformation of a contact lens by maintaining electrical conductivity under strains due to its semi-fluidic nature. The fabricated Galinstan-coils successfully demonstrated post-deformation tolerance up to 166.67% strain. The fabricated contact lens prototype with a Galinstan-coil showed the maximum wireless power reception of 32.4 μW with a power efficiency of 0.75% from an external coil located 5 mm away within a frame of eyeglasses. 

This article reports the fabrication, characterization, implementation, and microsystem integration of micromachined flexible silicon solar cells to supply electric power to smart contact lenses. Single silicon solar cell shows the open circuit voltage (V oc ) of 0.5 and 0.55 V Under indoor and outdoor lighting conditions, respectively. The V oc enhanced to 1.25 and 1.65 V after making series connections between three cells. The maximum power output of 50 µW and 2.7 mW are recorded under indoor and outdoor lighting conditions. Furthermore, a power management IC is used to boost up the voltage to 3.3 V and efficiently store or use the generated energy.