Detection of Urea in Adulterated Milk With 3% Fat Using Disposable Paper Sensor

Urea is one of the major adulterants in milk, which is added to increase the solid-not-fat and protein contents in adulterated milk, as well as its shelflife. Prolong consumption of excess urea beyond the permissible limit (70 mg/dL) leads to kidney disease and renal failure. As mostly run through unorganized sectors, reliable quality check of milk in India can only be done in the consumer end. That requires an in-home, portable device with simple test protocol. A disposable urea sensor is designed in this work from this motivation. It adopts impedimetry-based enzymatic technique, which is integrable with smart devices. Its disposable nature avoids any calibration shift resulted by the fat contents present in milk. The presence of urease makes the sensor sensitive to urea and tells the exact concentration in the range of 20-250 mg/dL. The response is linear and sensitivity is 1.36 Omega/mg/dL.