Experimental setup of the device detecting lead ions in a drop of water. Credit: Bandaru Lab/UC San Diego
University of California San Diego engineers developed a novel ultra-sensitive graphene sensor to detect trace level lead ions in water. The sensor is capable of record-breaking femtomolar detection limits, one million times more sensitive than current sensing technologies.
Published in Nano Letters, the sensor is comprised of a single graphene layer mounted on a silicon wafer. To achieve its astounding detection limits, the detector also contains a linker molecule on its surface to serve as an anchor for ion receptors.
“With the extremely high sensitivity of our device, we ultimately hope to detect even the presence of one lead ion in a reasonable volume of water,” said Prabhakar Bandaru, a professor in the Department of Mechanical and Aerospace Engineering at UC San Diego. “Lead exposure is a serious health concern, and it has been indicated that a lead concentration at the level of parts per billion in drinking water could lead to pernicious outcomes, such as stunted human growth and development.”
Another contributing factor to its sensitivity to lead is the inclusion of an aptamer as the ion receptor. Known for their existing selectivity towards specific ions, the aptamer was also enhanced by tailoring its DNA to ensure the sensor would only be triggered after binding to a lead ion. This aptamer inclusion not only improves the sensitivity of the sensor but also provides unparalleled selectivity to the target ion.
Current methodologies for lead detection rely on robust instrumentation or low-cost home test kits which offer poor reliability and detection limits. “The technology that we developed aims to overcome the issues of cost as well as reliability,” said Bandaru. “Our goal is for it to be eventually deployed in homes, given its relative ease of manufacture.”
Despite the sensor only being a proof of concept, Bandaru believes the sensor could be implemented in several real-world applications. The team intends to begin scaling up sensor production for commercial use by collaborating with industry partners.