Microfabricated Low-Profile Tunable LC-Refractive Fresnel (LCRF) Lens for Smart Contacts

Banerjee, Aishwaryadev; Ghosh, Chayanjit; Karkhanis, Mohit; Deshpande, Adwait; Pourshaban, Erfan; Kim, Hanseup; Mastrangelo, Carlos H.

doi:10.1364/cleo_at.2022.aw4c.3

Cited by 8 publications

(6 citation statements)

References 3 publications

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“…An adaptive SCL microsystem should consist of a scleral eye-tracking distance ranger [12]- [14], a compact energy source [15]- [19] and most importantly, an electro-optical tunable lens which provides different distance-dependent optical powers [20], [21]. For this application, the tunable lens must consume very little power yet provide adequate accommodation (~4D) with low actuation voltages.…”

Section: Scl Microsystem Requirementsmentioning

confidence: 99%

“…VLCFs can also be formed by LC-filling of grooved cavities (Fig. 1(b)) [21], [40] . The HPE voltage tunability feature at first seems attractive, but the wire routing of many electrodes and the generation of many analog voltages on the SCL substrate makes the layout difficult and the drive electronics complex.…”

Section: Varifocal Lc Fresnel Lens Designmentioning

confidence: 99%

“…The light exiting the polarizer is next passed through by a flat, very thin orthogonally twisted nematic LC cell (TNC). The TNC acts as a voltage-controlled polarization rotator[21],[36] that provides the optical tunability of the Fresnel LC lens through Eq. (2).…”

mentioning

confidence: 99%

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Refractive-type Varifocal Liquid-crystal Fresnel lenses for smart contacts

Banerjee¹,

Ghosh²,

Karkhanis³

et al. 2023

Preprint

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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 VRMS for 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.

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Section: Scl Microsystem Requirementsmentioning

confidence: 99%

Section: Varifocal Lc Fresnel Lens Designmentioning

confidence: 99%

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Refractive-type Varifocal Liquid-crystal Fresnel lenses for smart contacts

Banerjee¹,

Ghosh²,

Karkhanis³

et al. 2023

Preprint

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“…At the forward unrotated magnetometer configuration, the quaternion representation of the magnetometer local axes unit vectors expressed in terms of the frame axes unit vectors are 𝑄(𝑥 ̂𝑚𝑜 ) = (0,0,0,1) 𝑄(𝑦 ̂𝑚𝑜 ) = (0,1,0,0) 𝑄(𝑧̂𝑚 𝑜 ) = (0,0,1,0) (18) where '×' is the quaternion product operation, and the -1 exponent in a quaternion indicates its inverse, its quaternion complex conjugate. Equations ( 17 which is identical to (12).…”

Section: Alternate Solution Via Quaternion Rotationmentioning

confidence: 99%

“…Smart contacts require several subsystems for their realization. Some key components are varifocal lenses [12]- [14], various types of power sources like wireless power transfer [15]- [18], metal-air batteries [19]- [21], solar cells [22]- [25] and other bio-fluid based energy harvesters [26]- [28], object distance sensors [29]- [31], electronic components and flexible interconnects between these subsystems [32] and soft packaging to encapsulate these components [33], [34]. All these subsystems must conform to the small form factor of a thin shell in contact with the eye and operate with very little electrical power consumption as possible as energy storage is, in general proportional to the system volume, and for this application, the thickness is in the order of 1 mm or less.…”

Section: Introductionmentioning

confidence: 99%

Ultralow Power On-the-Eye Vergence and Distance Sensing Through Differential Magnetometry

et al. 2023

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We demonstrate the realization of a very low energy, on-the-eye vergence-type distance ranger based on sensing of a locally-uniform vector field, specifically the earth's magnetic field. This ranging method is passive, only requiring measurement of the magnetic field vector at both eyeballs utilizing magnetometer chips placed on the eye scleral regions. The eye vergence angle and range distance are calculated from these two vector quantities. The method can obtain a range reading with as little as 118 nJ of energy consumed per eye for 3.3V and 50 nJ when operated at 1.9V. This method is thus suitable for applications where energy storage is very limited such as in smart contacts vision correcting microsystems.

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Power Scavenging Microsystem for Smart Contact Lenses

Pourshaban,

Karkhanis,

Deshpande

et al. 2024

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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–O2 metal–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−2 and 2.5 mW cm−2 under 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.

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Microfabricated Low-Profile Tunable LC-Refractive Fresnel (LCRF) Lens for Smart Contacts

Abstract: Using high-performance LC (E7) filled microfabricated refractive Fresnel chambers, we experimentally demonstrate a thin low-profile adaptive optical system with high analog tunability (2.1 D) that can be integrated with an adaptive contact-lens system.

Cited by 8 publications

References 3 publications

Refractive-type Varifocal Liquid-crystal Fresnel lenses for smart contacts

Refractive-type Varifocal Liquid-crystal Fresnel lenses for smart contacts

Ultralow Power On-the-Eye Vergence and Distance Sensing Through Differential Magnetometry

Power Scavenging Microsystem for Smart Contact Lenses

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