Hamdi Torun
Arda Deniz Yalcinkaya
Gunhan Dundar
Ozgue Kaya
Northumbria University, Newcastle Upon Tyne, UK
Asmart contact lens has been developed that is capable of continuously measuring intraocular pressure (IOP) over 24 hours. A technological breakthrough toward this capability is a metamaterial-based sensor that offers unprecedented advantages for wireless strain sensing because it is electrically passive, ultrasensitive, low cost, and can be fabricated and integrated into contact lenses using simple and cost-effective processing steps. The sensor is based on the principle of resonant frequency shift of a metallic resonator with metamaterial properties under mechanical stress. This is a novel approach to accurately monitor IOP by measuring changes in the geometry of a sensor placed on the cornea. The electrically passive sensor embedded into a contact lens is operated without any battery or power requirements. The data are collected wirelessly by transmitting a very low power radio frequency (RF) signal generated by a lightweight Holter-monitor-like device comprising an electronic circuit and a custom design wearable antenna.
The team has demonstrated the operation of the full system in a clinical pilot study, published in Contact Lens and Anterior Eye. The sensor has been designed and tested for scalability and low manufacturing costs. Manufacturing of the sensor currently uses standard and highly scalable screen printing and/or photolithography methods where thousands of sensors can be manufactured simultaneously. Then, the sensors are embedded into contact lenses using conventional molding processes that can be automated easily. The electronics readout is based on off-the-shelf components and can be manufactured using standard PCB processes. Overall, the system can be manufactured cost-effectively at scale.
Glaucoma has become the second leading cause of preventable blindness after cataracts. Currently, over 70 million are affected by this disease worldwide, of which 12 million are in the EU. This number is likely to increase to 112 million individuals by 2040. The current medical practice for the management of glaucoma is to assess IOP during a clinic’s visit. Due to the circadian cycle of IOP, shorter timescale variations and measurement imprecision, the snapshot measurement in clinic does not sufficiently characterize the IOP insult to an eye.
An ideal IOP measurement strategy is to observe the circadian cycles of IOP variation in a period of 24 hours spanning a single day and repeating this measurement strategy periodically over an extended period of time to more precisely estimate the IOP insult to the eye. This invention offers a evolutionary measurement capabilities to address this unmet clinical need. It has the potential to disrupt and contribute to the growth of the market, offering the first noninvasive, cost-effective device for continuous monitoring of glaucoma.
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