Low-Profile Induced-Voltage Distance Ranger for Smart Contact Lenses

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

doi:10.1109/tbme.2020.3040161

Cited by 13 publications

(6 citation statements)

References 25 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%

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%

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

Banerjee¹,

Ghosh²,

Karkhanis³

et al. 2023

Preprint

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“…Therefore, the use of wireless integrated circuits helps the commercialization of SCLs further. [121,123,136] Future research can focus on the biocompatibility of integrated circuits to realize the use of SCLs in clinical trials.…”

Section: Wireless Sensing Circuitsmentioning

confidence: 99%

Smart Contact Lenses for the New Era of IoT: Integrated Biosensors, Circuits, and Human–Machine Interface Systems

Xiang

Wang

Zhang

et al. 2022

Adv Materials Technologies

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The circuit helps the sensors realize signal readout, conversion, transmission, and complex logic functions. [19][20][21] The human-machine interface (HMI) system plays the role of the application layer in the field of the IoT. [22][23][24] By presenting the sensor information to users in a simple and user-friendly interface, the HMI system enables a good user experience. [25,26] In particular, in the context of the coronavirus disease 2019 (COVID-19) pandemic, the use of smart electronic technology to achieve real-time and wireless interactive sensing is necessary. [27][28][29] Smart contact lenses (SCLs) have been employed for monitoring information regarding the eyes, including physical information (e.g., pressure and temperature) and chemical information (e.g., glucose, protein, and pH). [30][31][32][33][34] These physiological signals are closely related to human health. For example, excessive intraocular pressure (IOP) can induce glaucoma, [35] the abnormal temperature of the ocular surface can cause dry eye syndrome, [36] and excessive glucose in tears may predict diabetic retinopathy. [37] Non-invasive monitoring of human health by using SCLs will aid in better understanding of the physiological state of the eyes and even the body; subsequently, effective measures can be employed in a timely manner for the early prevention or treatment of certain diseases. As personal health information can be monitored in real-time by using SCLs, patients no longer need to go to the hospital or rely on large medical equipment. [38][39][40][41][42] Therefore, the development of SCL devices in view of the rapid advances in IoT technology is an important research topic.In this review, we focus on the latest progress and prospects of integrated biosensors, circuits, and HMI systems on SCLs under the background of the rapid development of the IoT technology, as shown in Figure 1. First, we discuss the integration of biosensors on SCLs for physiological information monitoring of the eyes, including IOP monitoring, corneal sensing, color signals sensing, tear pH monitoring, and glucose sensing. Next, we focus on wireless communication circuits integrated into SCLs, which have different functions, such as physiological signal sensing circuits, sensing circuits for disease treatment, and circuits for power supply. Furthermore, we summarize SCLs used in the HMI system. WhetherThe rapid development of the Internet of Things (IoT) technology endows some traditional devices with intelligent functions. Compared with traditional contact lenses used for correcting vision or beautifying the eyes, smart contact lenses (SCLs) are developed to monitor some physiological information of the eye. Sculls can be used to continuously monitor eye diseases noninvasively in real-time. As a personal electronic device, SCs can aid people in understanding their physical condition better without affecting their personal life. This review mainly discusses the development direction and problems associated with sculls from the perspective of the IoT. SCs c...

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“…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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Low-Profile Induced-Voltage Distance Ranger for Smart Contact Lenses

Cited by 13 publications

References 25 publications

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

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

Smart Contact Lenses for the New Era of IoT: Integrated Biosensors, Circuits, and Human–Machine Interface Systems

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

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