New Lab-on-a-Chip Sensor Enables Continuous pH and Chlorine Monitoring in Pools

According to a new study a novel microchip can deliver accurate and consistent pool chemistry for reliable pool management, thus enabling continuous pH and chlorine level monitoring in swimming pools.

Thanks to the continuous monitoring, water hygiene and safety can be considerably enhanced for over 2.7 million Australians.

The new “lab-on-a-chip” technology was created by the University of South Australia (UniSA) with the help of top-class fabrication capabilities, in collaboration with Tekelek Australia, an electronics research and manufacturing company. The technology renders monitoring of swimming pools more reliable, more cost-effective, and easy to install—even in existing pools.

According to Associate Professor Craig Priest, a researcher and micro/nanofabrication expert from UniSA, the microfluidic chip could be a valuable addition to Australian swimming pools, specifically with COVID-19 making people more aware of the significance of pool hygiene.

Pool chemistry keeps swimmers safe from viruses and bacteria, yet getting it right takes a lot of effort. Backyard swimming pool management would be a lot easier with a continuous and automated water quality sensor that can reliably measure accurate chlorine and pH levels all summer. The sensor that we’ve developed is essentially a ‘lab-on-a-chip’—a network of microscopic pipes running through a credit card-sized chip.

Craig Priest, Associate Professor, University of South Australia

Priest continued, “The chip quickly and continuously does all the work of a chemistry laboratory using tiny amounts of chemical, without leaving the poolside. For pool owners, this removes the arduous task of manually testing swimming pools and avoids overuse of pool chemicals, which saves time, money and, most importantly, the risk of infection from incorrect pool chemistry.”

In Australia, 2.7 million people (almost 13% of the population) reside in a house that has a swimming pool. At present, current pool monitoring systems—wireless swimming pool sensors including high-cost hardware or labor-intensive manual testing kits such as those bought from hardware stores—monitor the safety of chemicals in pools.

However, according to Assoc Prof Priest, making pool owners become backyard chemists could make the summer fun a health hazard.

Many of the domestic pools samples showed flaws in manual pool testing,” Assoc Prof Priest says. One family’s swimming pool was seriously overdosed with chlorine, yet they had no idea. Having just bought their home, they did a quick water check at the local pool shop and were told that there was ‘enough’ chlorine in the water but didn’t show that there was actually too much.

Craig Priest, Associate Professor, University of South Australia

“A few weeks later, the chlorine levels dropped to zero, which not only highlighted a problem with the chlorinator, but also showed how quickly pool chemistry can become unsafe,” added Priest.

As part of the study, samples from 12 swimming pools (two public, nine domestic, and one outdoor public) were tested, with measures taken on several occasions. Each sample included its own ambient situation—high leaf matter, different chlorination methods, frequent public use—thus guaranteeing realistic sensor challenges.

While a chlorine over-dosage can have adverse effects on the health of the eyes, skin, and immune system, an under-dosage poses the risk of infection for swimmers.

According to Stephen Thornton, a research collaborator from Tekelek Australia, the new microchip exhibits mass potential for both public and private swimming pools.

Right now, the need to stay healthy is paramount for us all, and while we generally feel safe in our own backyard, we must remember that all swimming pools need to be accurately and efficiently monitored to ensure water safety. Partnering with UniSA has meant that we’ve been able to develop a product that truly meets the needs of the market, while also ensuring public health and safety.

Stephen Thornton, Tekelek Australia

At present, the researchers are in the final stages of creating the microchip with industry and hope to make it available on the market soon.

Journal Reference:

Elmas, S., et al. (2020) Photometric Sensing of Active Chlorine, Total Chlorine, and pH on a Microfluidic Chip for Online Swimming Pool Monitoring. Sensors. doi.org/10.3390/s20113099.