When algae produce toxins in lakes or other waterways, it is best to detect too much as soon as possible. A new smartphone-based system can help, providing on-site readings in minutes. Typically, researchers need to monitor levels of potentially harmful algae by collecting water samples from water bodies and then taking them back to the lab. The problem is that by the time these samples arrive in the lab for testing, the number of algae may have increased significantly.
With this in mind, scientists at the National University of Singapore have developed a three-part system: a 3D printing platform with electronic components, a smartphone placed on the platform, and a reusable microfluidic chip.
The chip is coated with a polymer called titanium oxide, which generates current when exposed to light. Place it on your smartphone’s screen and deposit water droplets on it. The phone then projects a graph of bright and dark areas on the chip, creating a voltage change on its surface. This changes the surface tension of the droplets and causes them to flow into dark areas.
There, tiny microfluidic channels on the chip surface guide water to the transparent area of the device, above the smartphone camera. In addition, as the water flows through the channel, the chemical mix of any algae cells that stain the presence is present.
With the help of the platform’s built-in LED light source and green filter, the phone is then able to take pictures of water samples, with all the algae cells fluctuating. They can then be easily calculated through a companion app, allowing users to determine whether algae levels in the lake are rising to dangerous levels.
The entire process can be done in 15 minutes on site, and the entire unit (excluding mobile phones) costs around $220 to manufacture.
In tests with traditional blood cell counters, the researchers found that smartphone systems were 90 percent accurate in monitoring levels of four different types of toxin-producing algae. Further development will further increase this figure.
Bae Sung Woo, lead scientist and associate professor, said: “The combination of sample preparation, data capture and analysis on the chip makes our system unique. With this tool, we can conduct water quality testing anytime, anywhere. “
A paper on the study was recently published in the journal Harmful Algae.