Ultra-Thin "Serpentine Mesh" Sensor Offers Health Monitoring Through Soft Contact Lenses

Made using MoS₂ transistors, the sensors gather optical, temperature, and glucose data for unobtrusive healthcare.

An international team of researchers and engineers have released details of a new ultra-thin sensor layer designed for the creation of smart contact lenses, combining a photodetector, temperature sensor, and a glucose sensor.

"Our ultra-thin sensor layer is different from the conventional smart contact lenses, with their rigid or bulk sensors and circuit chips that are sandwiched between two contact lens layers and make contact with tear fluids via microfluidic sensing channels," claims first author Dr. Shiqi Guo of the work. "This new layer could instead be mounted onto a contact lens and maintain direct contact with tears, thanks to its easy assembly, high detection sensitivity, good biocompatibility and mechanical robustness; further, it doesn't interfere with either blinking or vision."

"Here, we demonstrate a flexible approach for fabrication of multifunctional smart contact lenses with an ultra-thin MoS₂ transistors-based serpentine mesh sensor system," the team writes in the paper's summary. "The integrated sensor systems contain a photodetector for receiving optical information, a glucose sensor for monitoring glucose level directly from tear fluid, and a temperature sensor for diagnosing potential corneal disease."

"The COVID-19 pandemic has had an enormous impact on the entire scientific community, with many of us asking how our work could help those suffering from similar future medical emergencies," adds co-author Dr. Yunlong Zhao of the inspiration behind the project. "We are confident that devices that utilise our sensor layer system could be used as a non-invasive way to help monitor and diagnose people's health. Our results provide not only a unique and simple method for manufacturing advanced smart contact lenses but also novel insight for designing other multifunctional electronics for human-machine interface."

According to testing carried out on the design, the sensor layer is easily incorporated into soft contact lenses while leaving the sensors exposed to the tear fluid for high sensitivity. The donut serpentine mesh architecture is said to be both mechanically robust and stretchable, providing improved eye comfort over rival designs, and highly transparent so as not to impair the wearer's vision.

The team's work has been published under open-access terms in the journal Matter.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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