Scientists develop affordable sensor to detect lead in water

Artist’s impression of the chip surface, showing the on-chip light interferometer used to sense the presence of lead. The lead binding process to the crown ether is shown in the inset. Credit: Jia Xu Brian Sia

Engineers from MIT, Nanyang Technological University, and several companies have created a new, affordable technology to detect and measure lead concentrations in water.

This innovation could significantly help address the global health issue of lead contamination.

The World Health Organization estimates that 240 million people worldwide are exposed to unsafe levels of lead in their drinking water.

Lead exposure can harm brain development in children, cause birth defects, and lead to various neurological and cardiac issues.

In the U.S. alone, around 10 million households still receive drinking water through lead pipes, contributing to over 1 million deaths annually, according to MIT postdoc Jia Xu Brian Sia, the senior author of the study describing the new technology.

Traditionally, testing for lead in water requires expensive and bulky equipment, taking days to yield results.

Simple test strips can only indicate the presence of lead without quantifying its concentration.

The new system developed by the research team can detect lead concentrations as low as 1 part per billion with high accuracy, using a compact, handheld device. This technology provides instant quantitative measurements with just a droplet of water.

The team’s findings, published in Nature Communications, involve researchers from MIT, Nanyang Technological University, and other institutions.

The goal was to create a simple detection method using photonic chips, which utilize light to perform measurements.

The challenge was to attach certain ring-shaped molecules, called crown ethers, to the photonic chip surface. These molecules are capable of capturing specific ions like lead.

After years of effort, the team succeeded in achieving this attachment through a chemical process called Fischer esterification.

This breakthrough enabled the development of a chip that can detect lead in water at very low concentrations. The device works accurately even in water with varying acidity levels, ranging from pH 6 to 8, covering most environmental samples. It has been tested in both seawater and tap water.

Current lead testing methods require an expensive device called an inductive coupled plasma mass spectrometer, which is large and needs skilled technicians. In contrast, the new chip system is the core innovation, according to MIT graduate student and lead author Luigi Ranno.

Developing this technology into a practical handheld device involves combining the chip with a small laser and other components, a process requiring mechanical, optical, and chemical design, as well as establishing a supply chain.

The new system can be adapted to detect other contaminants, such as cadmium, copper, lithium, barium, cesium, and radium, by using different crown ethers tailored to each specific ion. This adaptability could lead to a versatile tool for water quality monitoring.

Ranno emphasizes the importance of making water testing more accessible, especially in developing countries. “People don’t measure their water enough because they need to collect and prepare samples for expensive equipment,” he says.

A compact, handheld device that even untrained personnel can use for on-site monitoring at low costs could revolutionize water testing.

Professor Juejun Hu, another key researcher, hopes for the technology’s rapid implementation to benefit society. “This innovation could have a significant impact on public health,” he says.

Other experts, like Hou Wang from Hunan University, commend the potential of this research to monitor industrial wastewater and detect multiple metal elements simultaneously.

The collaborative effort included researchers from various institutions and companies, utilizing advanced facilities at MIT, Harvard University, and Nanyang Technological University.

This new technology represents a promising step forward in ensuring safer drinking water worldwide.