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Cornell ECE 5030 students Uma Mohan, Sarvesh Sukhatme and Priyanka Venkatesh have designed a Portable Device for Measuring Hydration and Body Fat. The project passes a small current through the body to measure the amount of hydration in the person. A 940 nm LED is used to detect the amount of fat the person has by shining it through a part of the body, the amount of light that passes through allows them to calculate the body fat of the person.
“We used a LM358 Opamp to make a voltage dependent constant current source. Setting the resistor connected to pin2 as 200 ohms sets the current as the (voltage magnitude/200) A. The voltage source used was a square wave with magnitude 0.2V and frequency 2Hz.”