Novel technique helps develop ultra-thin sensor for smart contact lenses

Engineers from the University of Surrey - together with partners from Harvard University; University of Science and Technology of China; UK National Physical Laboratory; George Washington University, and Zhejiang University Ningbo Research Institute - have unveiled how they have developed a breakthrough sensor system and manufacturing process.

In a published paper, the global team of engineers revealed that the new contact lens sensor system contains a photodetector for receiving optical information, a temperature sensor for diagnosing potential corneal disease, and a glucose sensor for directly monitoring the glucose levels in tear fluid.

Dr Shiqi Guo, a current postdoctoral research fellow at Harvard University, said: “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.

“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.”

Professor Sheng Zhang, co-author from Zhejiang University said that the multifunctional contact lens with field-effect transistors can “provide diversified signals from eyes, which could be combined with advanced data analysis algorithms to provide personalised and accurate medical analysis for users”.

“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,” said Dr Yunlong Zhao, a lecturer in energy storage and bioelectronics at the University of Surrey. 

He added: “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.”