These Creative Kids Designed A Way To Measure All The Plastic In The Ocean

Not content with the usual beach cleanups, they came up with a sensor that scans the ocean for trash.

It’s hard to know exactly how much plastic trash is floating around in the ocean–one recent estimate was five trillion pieces, but most of the tiny scraps haven’t been measured yet. Researchers may soon have a better answer thanks in part to the creative work of kids as young as five.


Cesar Harada, a Hong Kong-based designer known for his shape-shifting sailing robot, started working with a group of children from a local school and ended up with an optical sensor that can automatically scan the ocean for data on trash.

The students, from Hong Kong Harbour School, had done beach cleanups before, but wanted to do more. “The school was interested in doing something a bit more creative,” says Harada.

While Harada helped make it happen, the final design was based on the kids’ ideas. “One kid had an idea of building a machine in the shape of a shark, so fish would be afraid and not be captured,” says Harada. “Another thought of having a big net so we could physically capture the plastic, and compare it to what we’ve sensed through the optical sensor. A very smart and scientific idea.”

Others suggested different ways to attract the plastic, and different shapes–like a whale-sized sensor, because typical sensors are tiny and can’t give a precise measurement over a large area. As they incorporated some of the ideas, the team hacked together a prototype from lamps, webcams, and plumbing supplies.

“We worked from the things that we had available at hand,” says Harada. “Some said, ‘I have a toy boat I can give to the experiment.'”

After testing a prototype in a swimming pool and the harbor, the team shared the plans on the DIY site Instructables. Now, Harada is collaborating with Ocean Cleanup–the organization led by a 20-year-old inventor who aims to use giant arrays to collect plastic trash–to put the sensors to work.


“They’ve been asking me to join their engineering team,” he says. “But I wasn’t interested in joining unless the project was open source. And so after we had a prototype of the optical sensor, I told them I would be happy to work on it with them if it was open source.” They agreed.

The students didn’t stop with the plastic sensor. After seeing a news story about Bangladeshi children dealing with an oil spill, they worked with Harada on a low-cost sensor that can measure oil pollution in water and then shipped the tools off to Bangladesh. They also helped Harada, over Skype, as he took samples of radiation near Fukushima.

Soon they’ll have a new space to work: Hong Kong Maker Bay, under construction now, will be a massive maker space focused on social and environmental impact. “It’s a place where adults and kids can play together,” says Harada.

He’s genuinely convinced that the students have a meaningful role to play–the projects aren’t just educational. “I believe in the power of the creativity of kids,” he says. “I really think that they can give a substantial contribution to the field.”

“We can no longer shield kids from the ugly truth,” he says in a recent TED Fellows talk. “We need their imagination to invent better solutions.”


About the author

Adele Peters is a staff writer at Fast Company who focuses on solutions to some of the world's largest problems, from climate change to homelessness. Previously, she worked with GOOD, BioLite, and the Sustainable Products and Solutions program at UC Berkeley, and contributed to the second edition of the bestselling book "Worldchanging: A User's Guide for the 21st Century."