'Glucolight' Monitors Blood Sugar through Skin Contact

Medical Design Briefs INSIDER

A new sensor gauges blood sugar through skin contact. The “Glucolight” is initially to be used in premature babies to avoid hypoglycemia and subsequent brain damage.

Glucolight’s measuring head with the smart membrane.

The Glucolight, developed by Empa, Laboratory for Protection and Physiology, and the University of Zurich, Switzerland, spares premature babies blood samples and enables the blood sugar level to be monitored permanently. The sensor’s novel measuring technology includes several parts: a microdialysis measuring head, a “smart” membrane, light sources, a pump, and a microfluidics chip with a fluorometer.

The smart membrane contains special dye molecules, known as spiropyrans. If UV light is beamed onto these spiropyran molecules, they alter their chemical structure and become charged (polar).

When irradiated with visible light, they revert to their original, neutral structure. As a result, the membrane “opens” if irradiated with UV light, and glucose molecules diffuse relatively easily through the membrane from the skin. If irradiated with visible light, considerably fewer glucose molecules pass through the membrane.

The measurement involves sticking the measuring head, which is around three centimeters in size, to the baby’s skin and irradiating it with visible light; some glucose molecules diffuse through the membrane from the skin. On the other side of the membrane, the glucose is mixed with a fluid and pumped through the microfluidics chip, while enzymes are added to trigger a reaction.

During the reaction, a fluorescence appears, which the fluorometer measures, and the computer uses the reading to calculate the glucose concentration. The process is then repeated with UV light. The computer then uses these two different readings to calculate the premature baby’s blood sugar level.

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