There’s no sense in crying over spilt milk, but tears could hold the key to a continuous and non-invasive way to monitor glucose levels for patients with diabetes. The Dutch company NovioSense has created a tiny sensor that can measure glucose levels in tears, and wirelessly forward the results to a smartphone or other device using NFC (near-field communications) signals.
The flexible device is shaped like a spring, and consists of three different sensors and electrodes. These can accurately measure tiny amounts of glucose, and then NFC circuitry at one end can transmit the readings. The entire device is smaller than a grain of rice, and is coated in a soft gel. The patient places it inside the lower eyelid of one eye, where it can stay for at least two weeks though the company hopes to extend the wear time even longer.
In addition to eliminating finger sticks to get blood drops, the device can provide continuous monitoring which provides a much more accurate view of the patient’s glucose levels throughout the day. It also can provide its data to an automated insulin pump, which could maintain a proper blood sugar level more efficiently and accurately. The company is still developing the product, and has completed animal trials. It has demonstrated that there is a close correlation between the glucose levels in the blood and in the tears, although the level in tears is much, much lower. They hope to start clinical trials with human subjects soon.
The fascinating aspect of this story is that it could open the doors to all sorts of biometric testing through tears. Along with sweat, tears contain hundreds of biomarker chemicals that could be helpful in diagnosing and monitoring diseases and chronic conditions. A temporary, tiny, low-cost device tucked under an eyelid could provide continuous monitoring of data that would normally require a trip to a hospital for lab work that only gives a single snapshot of information.