Can't measure trace elements accurately? This graphene sensor has a million times higher sensitivity!

Popular Science Times (Intern Wang Yuke) Engineers at the University of California, San Diego have developed an ultra-sensitive sensor made of graphene that can detect extremely low concentrations of lead ions in water.

The device has achieved a detection limit of lead in the femtomolar range, which is 1 million times more sensitive than previous technologies. This scientific research result was recently published in the international academic journal Nano Letters.

Lead exposure is a serious health problem. Experts have pointed out that lead concentrations of one part per billion in drinking water may affect human growth and development.

The device in the study consists of a single layer of graphene mounted on a silicon wafer. Graphene has a remarkable conductivity and surface-to-volume ratio, which makes it an ideal platform for sensing applications. The researchers enhanced the sensing capabilities of the graphene layer by attaching molecules to its surface.

The researchers used aptamers as ion receptors, which are short single-stranded DNA (deoxyribonucleic acid) or RNA (ribonucleic acid). The binding affinity of the receptors for lead ions was further enhanced by customizing the DNA or RNA sequence, which would ensure that the sensor would only trigger when bound to lead ions.

The researchers also analyzed the system's thermodynamic parameters, such as binding energy, capacitance change, and molecular conformation, and found that they played a key role in optimizing the sensor's performance. By optimizing each thermodynamic parameter, as well as the design of the entire system, from the electronics and materials all the way to the ion receptors, the researchers created a sensor that can detect lead ions with unprecedented sensitivity and specificity.

"This technology is designed to overcome cost and reliability issues," said Bandarushi, an author of the paper. "Given its relative ease of manufacture, our ultimate goal is to use it in homes."