Waterproof sensor can detect dirty swimming pools

 Australian researchers have developed a new microchip capable of continuously monitoring pH and chlorine levels that they say should make swimming pools safer.

 The device is the work of a team at the University of South Australia, who say their new ‘lab-on-a-chip’ technology makes monitoring swimming pools more affordable, more reliable, and is easy to install even on existing pools.

Associate professor Craig Priest said that the microfluidic chip could be particularly useful at the moment as Covid-19 makes people more aware of the importance of pool hygiene.

“Pool chemistry keeps swimmers safe from viruses and bacteria, yet getting it right takes a lot of effort,” he said.

“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.

“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 (13 per cent of the population) live in a house with a swimming pool. Existing pool-monitoring systems – either wireless swimming pool sensors with expensive hardware or labour-intensive manual testing kits such as those purchased at hardware stores – are used to monitor the safety of chemicals in pools.

“Many of the domestic pools samples showed flaws in manual pool testing,” Priest said.

“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 realise that there was actually too much.

“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.”

The research tested samples from 12 swimming pools (nine domestic, two public and one outdoor public) with measures taken on multiple occasions. Every sample had its own ambient situation – frequent public use, high leaf matter, different chlorination methods – ensuring realistic sensor challenges.

An over-dosage of chlorine can cause adverse health effects to the skin, eyes, and immune system, while under-dosage creates risks of infection for swimmers.

Research partner Stephen Thornton, from Tekelek Australia, said the new microchip has mass potential for both private and public 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.