A synthetic eye platform for testing contact lenses with integrated electronic biosensors

Abstract

Building an interface between a nano-scale system and the larger-scale world is of utmost importance in implementing and testing the system utility. By taking advantage of the enzyme function at the nano-scale, our group is developing functional contact lenses integrating electronic biosensors that can detect and report the level of glucose on the surface of the eye. In order to verify the functionality of the contact lenses we have developed a physiologically accurate mechanical model of a human eye which allows sensor characterization under thin-film conditions, in a controlled chemical environment. The polymer eye model replicates the geometry of an eye, the blinking motion of an eyelid, as well as the tear fluid input and output microchannels. Liquid used in the experiments was prepared to closely mimic the chemical and mechanical properties of biological tear fluid.

Wireless Communication and Power Harvesting in Wearable Contact Lens Sensors

“…Unpowered biosensors on electronic contact lenses are widely used for pressure, strain, glucose, pH, and temperature sensing. In such cases, smartphones and optical microscopes are generally used for data processing, those unpowered sensors rely on external devices to transfer [59], (b) First piezo-resistive IOP sensing was explored in 2004 for wearable glaucoma detection [97], (c) Wired glucose sensing for diabetes diagnose in 2010s [66], (d) Loop glucose design for wireless preparation in 2011 [70], (e) Capacitive IOP sensing utilizing frequency shifts due to impedance change by applied pressure [131], (f) Combination of nanomaterials, glucose and IOP sensing in 2019 [145], (g) Disease diagnosing and drug delivery integrated in the future. information either through light, colour, or microfluidic detections.…”

“…3(b)), which had a sensitivity of 240 μAcm -2 mM -1 for a glucose concentration range from 0.1 mM to 0.6 mM. The glucose electrodes were made from Ti/Pd/Pt metal structure, which was wirelessly powered under 1.8 GHz with 3 μW power consumption [67][68][69][70].…”

“…Contact lens sensors fabricated with photonic crystals, liquid crystals and phenylboronic acid react directly with pressure, temperature, and glucose molecules, which means they do not require an external power transfer unit [60][61][62][63][64]. Nevertheless, glaucoma or glucose detection using electrical and electrochemical sensors require power generation by either wired or wireless power transfer [65][66][67][68][69][70].…”