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Kidney disease is one of the complications due to long term diabetes. This is presently identified by serum creatinine and urea. Any elevation in serum urea is also exhibited in sweat. Moreover its concentration in sweat is three times higher than serum level. Based on these facts, we developed an electro optical technique to quantify sweat urea concentration and thus relating it to kidney disease. We approached this work in two stages; at first with aqueous solution and then with sweat samples. First aqueous solutions of 14 different urea concentrations ranging from 60 mg/dL to 350 mg/dL are prepared. When urease is added to this colorless solution, ammonia is liberated. Then ammonium ion reacts with the coloring agent and gives different shades of blue color. This variation in color is sensed by electronic circuitry, where RGB lights are incident sequentially in time controlled fashion. The reflected light from the solution are picked up by the light sensor and mapped on to CIE chromaticity chart. This kind of test is also performed on sweat samples collected from the participants and allowing it to sediment for 15 minutes. The result of this study demonstrates gradual variation in colour space in CIE chromaticity chart. (towards dark green) as the concentration of urea increases. Also sweat sample of control, diabetes and diabetic kidney disease (DKD) found to lie in the range of 60 to 135 mg/dL ,136 to 250 mg/dL and above 251mg/dL respectively. This technique being simple and non-invasive could help us self-examining kidney function among diabetes.
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