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Banerjee A, Ghosh C, Karkhanis MU, Deshpande A, Pourshaban E, Majumder A, Kim H, Mastrangelo CH. Refractive-type varifocal liquid-crystal Fresnel lenses for smart contacts. OPTICS EXPRESS 2023; 31:17027-17049. [PMID: 37157768 DOI: 10.1364/oe.489093] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
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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Pourshaban E, Banerjee A, Deshpande A, Ghosh C, Karkhanis MU, Hasan R, Rock ND, Kim H, Mastrangelo CH. Flexible and Semi-Transparent Silicon Solar Cells as a Power Supply to Smart Contact Lenses. ACS APPLIED ELECTRONIC MATERIALS 2022; 4:4016-4022. [PMID: 36035968 PMCID: PMC9406818 DOI: 10.1021/acsaelm.2c00665] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 07/18/2022] [Indexed: 05/25/2023]
Abstract
Supplying electric power to wearable IoT devices, particularly smart contact lenses (SCLs), is one of the main obstacles to widespread adoption and commercialization. In the present study, we have successfully designed, fabricated, and characterized semi-transparent, self-supported, and flexible single crystalline silicon solar cells using a single-sided micromachining procedure. Optical, mechanical, and electrical simulations, together with the practical measurements, verify the application of our developed solar cells to be mounted on a limited-footprint and flexible SCL. The 15 μm-thick silicon solar cells conformally fit on a dome-shaped contact lens (ROC = 8 mm) without any mechanical and electrical degradation. This homojunction photovoltaic device containing an array of micro-holes exhibits a V oc, J sc, and maximum power density of 504 mV, 6.48 mA cm-2, and 1.67 mW cm-2, respectively, at 25% visible light transparency under an AM1.5 one sun condition. Furthermore, the measurements were conducted under low-intensity indoor light conditions and resulted in a maximum power output of 25 and 42 μW cm-2 for the 50 and 25% transparent solar cells, respectively.
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Affiliation(s)
- Erfan Pourshaban
- Department
of Electrical and Computer Engineering, University of Utah, Salt Lake
City, Utah 84112, United States
| | - Aishwaryadev Banerjee
- Department
of Electrical and Computer Engineering, University of Utah, Salt Lake
City, Utah 84112, United States
| | - Adwait Deshpande
- Department
of Electrical and Computer Engineering, University of Utah, Salt Lake
City, Utah 84112, United States
| | - Chayanjit Ghosh
- Department
of Electrical and Computer Engineering, University of Utah, Salt Lake
City, Utah 84112, United States
| | - Mohit U. Karkhanis
- Department
of Electrical and Computer Engineering, University of Utah, Salt Lake
City, Utah 84112, United States
| | - Rabiul Hasan
- Department
of Electrical and Computer Engineering, University of Utah, Salt Lake
City, Utah 84112, United States
| | - Nathan D. Rock
- Department
of Materials Science and Engineering, University
of Utah, Salt Lake City, Utah 84112, United
States
| | - Hanseup Kim
- Department
of Electrical and Computer Engineering, University of Utah, Salt Lake
City, Utah 84112, United States
| | - Carlos H. Mastrangelo
- Department
of Electrical and Computer Engineering, University of Utah, Salt Lake
City, Utah 84112, United States
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