New Electronic Water Sensor Detects Lead from Corrosion

The electronic lead sensor features two pairs of electrodes. Photo courtesy of Wen-Chi Lin, Burns Lab, University of Michigan.

A new electronic sensor could alert users to the presence of lead within days. The sensor was developed by University of Michigan (Ann Arbor, Michigan) researchers following the water crisis in Flint, Michigan, where corrosion of service pipes after a water source change caused lead to leach into the water supply.

According to Mark Burns, T.C. Chang Professor of Chemical Engineering at the university, standard sample tests require running water for several minutes—missing any lead that leaches from the home’s own pipes.

Burns says the sensor, costing ~$20, could be placed at key points in a city water system and at taps in homes. The trick is separating lead from other metals that may be present, most only hazardous in very high doses.

In response, researchers designed the sensor to differentiate by relying on two pairs of positive and negative electrodes, each with a neutral neighbor. The negative electrode offers electrons to positive ions, capturing most metals. The metals are already oxidized in water, meaning they have given up some electrons. As such, they prefer to get electrons back.

However, lead is attracted to the positive side, as it is the only contaminant metal that readily loses more electrons and oxidizes further. As lead builds up on the positive electrode, it reaches the neutral electrode, closes the circuit, and generates voltage. Above a 1 V signal, the system registers a hit.

“There could be an app that would monitor all the taps, and it could just send you a message when it detected an event,” Burns says. Researchers are now seeking partners to bring the technology to market.

Source: University of Michigan, www.umich.edu