Study Demonstrates Novel Multifunctional Ultrathin Contact Lens Sensor

The huge impact of the recent COVID-19 pandemic, along with other chronic health risks or diseases, has triggered substantially the need to develop and apply bioelectronics and medical devices for real-time monitoring and diagnosis of health status.

Besides all such devices, smart contact lenses have gained immense interest because of their potential to directly monitor physiological and ambient information. Smart contact lenses fitted with high-sensitivity sensors could enable a non-invasive technique for the continuous detection of biomarkers in tears.

Moreover, they can be fitted with application-specific integrated circuit chips to further improve their functionality to receive, process and transmit physiological characteristics, manage health risks and illnesses and eventually promote health and wellbeing. Although there have been considerable efforts, earlier demonstrations still require multistep integration processes with restricted mechanical biocompatibility and detection sensitivity.

Scientists from the University of Surrey, National Physical Laboratory (NPL), Harvard University, University of Science and Technology of China, Zhejiang University Ningbo Research Institute, and other institutions recently created a multifunctional ultrathin contact lens sensor system.

The sensor systems are equipped with a photodetector for receiving optical information, imaging, and vision assistance; a temperature sensor to diagnose prospective corneal disease; and a glucose sensor to monitor the glucose level directly from the tear fluid.

"These results provide not only a novel and easy-to-make method for manufacturing advanced smart contact lenses but also a novel insight of designing other multifunctional electronics for Internet of Things, human machine interface, etc."

Dr Yunlong Zhao, Lecturer in Energy Storage and Bioelectronics, Advanced Technology Institute, University of Surrey

Dr Zhao, who led this study, is also a Senior Research Scientist at the UK National Physical Laboratory (NPL).

"Our ultrathin transistors-based serpentine mesh sensor system and fabrication strategy allow for further incorporation of other functional components, such as electrode array for electrophysiology, antennas for wireless communication, and the power modules, e.g. thin-film batteries and enzymatic biofuel cell for future in vivo exploration and practical application."

Dr Yunlong Zhao, Lecturer in Energy Storage and Bioelectronics, Advanced Technology Institute, University of Surrey

“Our research team at ATI, University of Surrey and NPL are currently working on these fields,” added Dr Zhao.

According to Dr Shiqi Guo, the first author of this study and current postdoctoral research fellow at Harvard University, “Different from the conventional smart contact lenses with rigid or bulk sensors and circuit chips that are sandwiched in between two contact lens layers and contacted with tear fluid via microfluidic sensing channels, our ultrathin sensor layer could be directly mounted onto a contact lens and maintain direct contact with tears, showing easy assembly, high detection sensitivity, good biocompatibility, good mechanical robustness and not interfering with either blinking or sight of vision.”

"This multifunctional contact lens with field-effect transistors is able to provide diversified signals from eyes, which could be combined with advanced data analysis algorithms, providing personalised and accurate medical analysis for users. This kind of research will become one of the major research directions at the Ningbo Research Institute."

Sheng Zhang, Study Co-Author and Professor, Ningbo Research Institute, Zhejiang University

In the words of Professor Ravi Silva, Director of the ATI at the University of Surrey, “Such innovative work fits in well with our institute’s mission, which is aiming to address the ‘grand challenges’ in energy, healthcare, information technology, sustainable technology and more generally, technologies associated with ‘quality of life’.”

Journal Reference:

Guo, S., et al. (2020) Integrated contact lens sensor system based on multifunctional ultrathin MoS₂ transistors. Matter. doi.org/10.1016/j.matt.2020.12.002.