Helping Monitor Toxic Algal Blooms

You’ve probably seen algal blooms — that green scum that grows on ponds and lakes. The blooms can be toxic to people and animals, and they can create dead zones in the water. They can also be costly to treat.

“If we can find some efficient way to monitor the distribution of algae on the water, we can know when they will become an algal bloom, and we can treat them before that,” says Zhiheng Sheng ’19.

He and Calvin Tang ’20, both physics majors, did a Mentored Advanced Project with Josh Weber, assistant professor of physics. Their goal was to build a prototype device that could stimulate algae with a laser to make it fluoresce.

The project involved electronics and coding, along with some optics and biology.

“It really brings a lot of different aspects together,” Sheng says. He enjoyed the hands-on nature of the project that required him to think critically and creatively to solve problems as they arose.

The measurement device he and Tang built from scratch uses a modulated LED signal to stimulate fluorescing algae and a photodiode to capture the signal. The LED is submerged underwater while the photodiode is placed at the surface.

They performed tests on the device in a tank to check the waterproofing and the signal’s transmission through water. They confirmed that the measurement device and all other individual electrical components could function under water.

Collaborating together and with Weber, the faculty mentor they relied on for electronics knowledge, was an important part of the research project’s success. This independent project was also part of a larger collaboration with Andreas Velten, assistant professor of electrical and computer engineering at the University of Wisconsin-Madison.

They’ve also been honing their professional communication skills through presentations at the Conference of Undergraduate Research and Scholarship at Monmouth College and Grinnell’s own Student Research, Scholarship, and Creative Activity Symposium.

Undergraduate research opportunities like this, which allow for deeper discovery, are a powerful part of a Grinnell education.