A contact lens with integrated telecommunication circuit and sensors for wireless and continuous tear glucose monitoring

Abstract

We present an integrated functional contact lens, composed of a differential glucose sensor module, metal interconnects, sensor read-out circuit, antenna and telecommunication circuit, to monitor tear glucose levels wirelessly, continuously and non-invasively. The electrochemical differential sensor module is based on immobilization of activated and de-activated glucose oxidase. We characterized the sensor on a model polymer eye and determined that it showed good repeatability, molecular interference rejection and linearity in the range of 0–2 mM glucose, covering normal tear glucose concentrations (0.1–0.6 mM). We also report the temperature, ageing and protein-fouling sensitivity of the sensor. We report the design and implementation of a low-power (3 µW) sensor read-out and telecommunication circuit to deliver wireless power and transmit data for the sensor module. Using this small chip (0.36 mm2), we produced an integrated contact lens with sensors and demonstrated wireless operation of the system and glucose read-out over the distance of several centimeters.

Concept for assembling individual nanostructure-based components into complex devices

“…12,17 Smart (bionic) contact lenses-contact lenses with added electronic functionality for, e.g., continuous glucose level monitoring [42][43][44][45][46] -may also benefit from this fabrication approach, since bionic contact lenses need to preserve their flexibility, softness, transparency, strength against mechanical damage, provide liquid and oxygen penetration, and at the same time integrate heterogeneous elements to form a complete and complex functional system at an overall thickness of below 100-200 lm. We envision that our approach may enable the development of a number of unique devices which may otherwise be unattainable.…”

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].…”

“…Consequently, the available pre-flight information on 'smart' or 'bionic' lenses refers to OTA power securement, based on radio frequency coupling in particular [2,6,8,11]. Other OTA protocols, not specifically involving lenses, draw on infrared and ultrasound.…”