A group of researchers in Korea presents their findings on research into wearable soft smart contact lenses capable of real-time monitoring of the glucose levels in tears.

Wearable electronics are devices that can be worn or are in contact with the human body to closely monitor an individual’s activities at all times, without interrupting or limiting the user’s motions. Examples of healthcare wearables are smart wristbands, smart glasses, e-skin, as well as robotic exoskeletons.Recently, smart contact lenses with embedded electronics have received considerable attention.

Cutting-edge research and development in wearable systems for healthcare monitoring is moving toward minimizing the size of wearable devices, measuring more vital signs, and sending reliable data through the internet. To enhance user comfortably, wearable electronics can be manufactured on transparent and flexible ultrathin films and placed onto the human body.

Realizing smart contact lenses, however, is still facing many challenges. The use of opaque materials for sensors, antennas, and the integrated circuit may block the user’s vision. The incompatibility between the brittle and rigid electronics and a soft lens can potentially cause a lot of damage to cornea or eyelid.The smart contacts will need to be transparent and soft, in order to be safe, comfortable, and easy-to-use.

To achieve these goals, a group of South Korean researchers used a rapid modeling approach, photolithography technology, and a metallization by evaporation technique to embed a glucose sensor, an LED pixel, rectifier circuit, and antenna onto a mechanical stress-tunable hybrid smart lens.The contact lens is made of soft and highly transparent elastomer, which is composed of a mechanically reinforced island to locate discrete electronic components, and an elastic joint to locate a flexible antenna and interconnected electrodes.

This nanostructured smart contact lens operated reliably in an artificial tear solution even under mechanical deformations, and it can respond to the changes of glucose level and simultaneously display the sensing information through the LED pixel. The researchers also tested their smart contact lens in a rabbit’s eye. They were able to monitor the change of the glucose level wirelessly without causing any harm to the testing subject.The researchers recently published their results in Science Advances.

This exciting study opens new doors to reshape the future of smart contact lenses for noninvasive and comfortable healthcare monitoring of human eyes and tears. This advance can be useful for people with diabetes and early diabetes, replacing conventional invasive finger-prick blood glucose testing.

Written by Man-tik Choy, Ph.D

Reference: Park, J.H., et al. 2018. Soft, smart contact lenses with integrations of wireless circuits, glucose sensors, and displays. Science Advances, 4(1), eaap9841. DOI 10.1126/sciadv.aap9841.