SensNews November 2018

25 Sensor100 November 2018 Noviosense’s In-Eye Glucose Monitor Continued... Last month, a startup company in the Netherlands called Noviosense quietly published data on human testing of its tear glucose sensor.The study was small—only six partic- ipants—but the results, published October 12 in the journal Biomacromolecules, look promising. “These are the best results I have seen yet” on tear glucose, says John L. Smith, a former executive for blood glucose meter maker LifeScan, who has devoted the latter part of his career to evaluating noninvasive glucose-sensing technologies as a consul- tant.“But substantial improvement is still needed for it to be good enough for monitor- ing.” Noviosense has taken a different approach to measuring glucose in tears. Instead of putting a sensor in a contact lens, Noviosense’s device is placed by the user under the lower eyelid. There, it accesses a reliable flow of tears that better reflects the true levels of glucose in the blood, says Christopher Wilson, founder and CEO of Noviosense. Plus, the design doesn’t dry the eye or impede vision, as contacts can, Wilson says. Noviosense’s flexible, spring-shaped coil drops in behind the lower eyelid—some- thing users can do themselves—and naturally stays put. The spring-shaped electrodes are coated in a biopolymer containing an immobilized enzyme that, when exposed to glucose, starts a chemical reaction. That reaction results in the oxidation of hydrogen peroxide, which can be detected by the electrodes using a chronoamperometric mea- surement. In Noviosense’s final design, the device will wirelessly transmit glucose data to a phone when it is held near the eye, or, for continuous measurement, to a pair of eyeglasses, Wilson says. The company compared its device to needle-based glucose monitors that measure the analyte in both blood (the gold standard) and interstitial fluid (a close second in accu- racy). The results: 95 percent of the data points from tear glucose measurements were either the same as blood or fell within an acceptable range of error. The tear data wasn’t as good as blood, but it was about the same as interstitial fluid. That beats previous studies by a lot. Reported by: IEEE Spectrum 1 5 November