Sliver-Sized Sensor Monitors Glucose

A fully functional, minimally invasive microscopic monitor can be placed just under the skin and seen with the naked eye for very accurate, continuous glucose levels shown by simple color changes. The monitor could also be used to monitor astronauts in outer space and for diagnostic telemedicine.

The sensor is 1-2 millimeters long and 100-200 um wide, penetrates the skin easily and painlessly so users may insert or reinsert it when needed, and can be operational at least for several days at a time. Colors in the tiny sensor, which is smaller than the tip of a pencil, gradually change from orange (low glucose level) to green and then to dark blue, as levels increase. A deep, darker blue indicates the highest glucose level that can occur in diabetics.

The sensor can be monitored by eyesight and by electronic telemetry, using a watch-like device worn by the patient for data processing. Sensing itself does not require a battery or the collection of blood samples. There is no deterioration of the skin surface or other areas inside the skin and no danger of track infection.

The sensor was developed by Dr. Miklos Gratzi, associate professor of biomedical engineering at Case Western Reserve University (Cleveland, OH, USA), and co-principal investigator Koji Tohda, a bioengineering researcher at Case. Dr. Gratzi got the idea for the sensor while removing a splinter from his son's finger. Since it showed no open wound in the skin, he thought that a sensor like a sliver would be ideal for all kinds of biomedical applications because the skin would heal very quickly above it and after that, no track infection could occur.

The research is being partially funded by the U.S. National Aeronautics and Space Administration (NASA). The sensor has obvious potential applications in space for monitoring vital markers such as ions and metabolites in astronauts who become ill, and for helping doctors make a diagnosis from several thousand miles away.

"Many diabetics could benefit from this technology, freeing them from having to take samples from their fingers several times a day to monitor blood sugar levels,” noted Dr. Gratzi. "The monitor could also help doctors with close monitoring of electrolytes, metabolites, and other vital biochemicals in the body, primarily those of critically ill patients.” According to Dr. Gratzi, lab and in vivo testing of the sensor in laboratory animals have been going well. He reports that the sliver sensor could be ready for human testing within six months.




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