A prick-free test for diabetes

By Kirtiman Awasthi
Published: Saturday 15 March 2008

diabetics can now now keep the needles at bay. They have an option--non-invasive semiconductor sensors--to test blood sugar levels. The sensor will tap acetone levels in the body, say researchers in Kolkata.

Acetone, derived form the breakdown of fat, is a volatile organic compound found in the breath of a person. Its concentration in a healthy individual ranges from 0.5-0.9 ppm (parts per million). The concentration increases in diabetics.

The researchers have made a nano gamma iron oxide semiconductor sensor (-Fe2 O3) for measuring acetone levels in breath, which works in spite of the presence of over 200 volatile organic compounds in human breath. Various semiconductor sensors have been tried out earlier but there were limitations. "Semiconductor sensors earlier could detect acetone only in the absence of volatile organic compounds and only at higher concentrations--above 10 ppm. Sensors need to detect acetone at a pathological range--0.5-2 ppm," says Shirshendu Chakraborty from Central Glass and Ceramic Institute, Kolkata.

-Fe2 O3 could detect acetone at concentrations as low as 1 ppm and in the presence of volatile organic compounds. To prepare the semiconductor, the researchers used ferric nitrate and hydrazine. They synthesized a powder and coated it on the surface of thin alumina tubes fitted with gold electrode. Gold electrode is used for carrying electrical charge from the body to the semiconductor sensor.

The findings will contribute to developing cheap and compact semiconductor sensors for non-invasive monitoring of blood sugar.

"The sensor should cost about Rs 500, which is less than three times the price of existing kit. It will last for three to five years," Chakraborty said. The researchers are looking for commercial partners. The study was published in Current Science (Vol 94, No 2, January 25, 2008).

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