A family in rural Kenya field tests the point-of-use fluoride biosensors. (Image: Janet Barsolai)

Researchers from Northwestern University have collaborated on the implementation of an accurate, low-cost, and easy-to-use test for detecting toxic levels of fluoride in water. The new biosensor device has been field tested in Kenya — proving that testing water for fluoride can be easily accomplished outside of a lab and accurately interpreted by nonexperts.

The study was co-led by Northwestern Anthropologist Sera Young and Synthetic Biologist Julius Lucks — the first time the married couple collected field data together. The work builds on prior research from the two.

In 2017, Young’s team developed the Water Insecurity Experiences Scales to provide a measurement of global water insecurity that takes human experiences into account. Young partnered with the Gallup World Poll to publish estimates for half of the globe using the WISE scale in 2022 in Lancet Planetary Health.

Prompted by this research, Lucks and his lab began to investigate naturally occurring biosensors. In 2020, the team published work on repurposing biosensors in a cell-free synthetic biology system, allowing the detection of harmful water contaminants such as fluoride in the field, naming the platform ROSALIND.

To further Young’s research on improving global water security, the latest iteration of the Lucks Lab’s ROSALIND technology improved the speed and usability of the device to allow for easy transport to locations where harmful levels of fluoride are a safety concern.

The research team collected 57 water samples from 36 households in rural Kenya to evaluate the accuracy of the fluoride concentration measurement when compared with the gold-standard method of fluoride photometer. They also designed their studies to examine whether the results could be easily interpreted by non-expert users.

The results showed that the point-of-use had an 84 percent chance of correctly predicting fluoride levels above the World Health Organization limit of more than 1.5 parts per million. In addition, the tests were found to be highly usable, with only 1 of 57 tests with an interpretation discrepancy between the user and scientific team.

“This is a whole new way to measure water quality,” said Young. “The study shows that we can get a test into people’s hands that is based on some very complex biology but works very simply.”

“It also points to the feasibility of such tests for other chemicals like lead and PFAS,” said Lucks.

A potential next step for the fluoride test could include mapping where geogenic fluoride is located globally. Closer to home in Chicago, the pair is interested in investigating the usability of an at-home test for rapidly detecting lead in water, as well as in leveraging this research as a model for interfacing social sciences with synthetic biology to increase the impact of synthetic biology innovations.

For more information, contact Stephanie Kulke at This email address is being protected from spambots. You need JavaScript enabled to view it.; 847-491-4819.