A contact lens with integrated micro solar cells

Abstract

We report the design, construction, characterization and in vivo testing of contact lenses incorporating solar cells. A fabrication process is outlined yielding freestanding 500 9 500 9 10 lm 3 single crystal silicon solar cells which are subsequently integrated into a contact lens. Collections of micrometer-scale solar cells are interconnected on the contact lens in order to maintain flexibility, cover the proper area, and take advantage of crystalline materials. The solar cells show maximum efficiency at wavelength 725 nm with conversion efficiency of 1.24% at 310 mV. The contact lenses were tested on live rabbits and no adverse effects were detected. Contact lenses equipped with solar cells can harvest usable power from the environment and pave the way for the deployment of standalone contact lens systems that can be used for healthstatus monitoring.

Electronic Contact Lens: A Platform for Wireless Health Monitoring Applications

“…Advances in nanotechnology have made it technically feasible to put together electronic devices such as sensors, transmitters, amplifiers, and even displays within the confines of standard‐size contact lenses . Delivering small amounts of power to these electronic components in a contact lens is a challenge.…”

Powering electronic contact lenses: current achievements, challenges, and perspectives

“…Drawing on the advances within nanotechnology, it has become technically feasible to fit electronics, for example, sensors, transmitters, amplifiers, and even displays, within the confinements of a standard-sized contact lens [5][6][7][8][9]. As regards sensors, they can be designed to gauge various features of biomarkers present in lachrymal fluid, while the complete circuitry arrangement, form factor, and opacity can be chosen not to impair vision.…”

“…Contact lenses are minimally invasive, and electronic lenses will offer real-time, non-traumatic biomarker probing, among many different possible applications. It should be emphasized, however, that whereas reports in popular media concerning smart contact lenses are stunningly impressive [1][2][3][4], actual, bona fide contact lens-based gadgets presented in the scientific literature are still quite far from real practical applications [5][6][7][8][9][10][11]. As the name implies, electronic circuitry relies on electric power, and even though the power demands of state-of-the-art micro-or even nano-electronics are minimal, some power is nonetheless needed.…”

“…While there is not much to say about the first approach [5,8,9], which is obviously a reasonable approach for scientific studies but certainly inappropriate for an end user, the second group is very diverse and includes over-the-air (OTA) electric power delivery [2,6,8,11], as well as solar [7] and electrochemical cells [12,13].…”

“…This approach, using 500 Â 500 Â 10 mm singlecrystal silicon solar cells, is definitely very interesting, at least for certain applications, if the performance of solar cells is further improved [7]. Still, quite an obvious disadvantage is related to the fact that electricity cannot be continuously provided, for example, when the eyes are closed.…”