One major development for wearable devices is to combine health monitoring technologies for medical application. A Korean research team had developed smart contact lenses to detect glucose; their result was published on Science Advances in January.

 A team from Ulsan National Institute of Science and Technology (UNIST), South Korea, released its research of smart contact lenses integrated with glucose sensors, wireless power transfer circuits and LED pixel to monitor the glucose level in tears and provide instant sensing result via the embedded LED display.

 Similar application in contact lenses was announced by Google in 2014, but no further progress of the project has been revealed afterwards.

 The lenses developed by the Korean team were composed with a hybrid substrate, a transparent and stretchable antenna and functional devices including rectifier, LED and glucose sensor. The sensor detects the glucose concentration in tears, and then the antenna with a rectifier receives electric power wirelessly to drive for the LED pixel for displaying visualized information. If the device senses high glucose level, the LED pixel would turn off. Meanwhile, according to the research, the wireless operations would not cause abrupt heating for the eyes for the concern of safety.

(Image: Park et al, 2018; Science Advances)

Researchers conducted in vivo tests on rabbits and reported no harmful effects. However, it has not been tested with human tears yet and some medical research had pointed out that the glucose level in tears might not reflect the glucose level of blood.