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Anna Du noticed plastic. It was scattered on the shoreline. She was walking along Castle Island's beach. That's in South Boston. She reached down to pick it up. She quickly realized there were many more tiny pieces. There were more than she could handle.

"When I realized how many pieces there were. It seemed impossible," says Du. She was in sixth grade at the time.

Du approached the problem like any good scientist. She did a little research. She learned that 8 million metric tons of plastic end up in the oceans every year. And there's an additional 150 million metric tons that are already there.

Then she got to work. She built something that could help solve the issue. She built a remote-operated vehicle. It is called an ROV. Her ROV could move through water. It could spot plastics on the ocean floor.

Du entered her ROV in the Broadcom Masters competition. It is a contest. It is for science. It is for technology. It is for engineering. And it is for math. These fields are known as STEM. It is for young students. Entries come from all over the world.

The competition is organized by the Broadcom Foundation and Society for Science and the Public. It has been running for eight years. Nearly 5,000 students were nominated this year. They were in sixth grade. They were in seventh grade. And they were in eighth grade. They were nominated after competing in regional science fairs. Of those, 2,500 applied online for consideration. That pool was narrowed down to 300 projects. These were dubbed "Broadcom Masters." The top 30 finalists gathered in Washington, D.C. They came to showcase their projects. The top prize was $25,000. There were other cash prizes as well.

Du's ROV is made with PVC pipes. It is inspired by ROVs of all sorts. It is like the Curiosity lander. Curiosity spies on the surface of Mars. It is also like the deep sea arctic Nereid ROV. It is at Woods Hole Oceanographic Institution (WHOI). Du's ROV has two separate systems. There is a navigation system. And there is a detection system. The navigation system is pretty simple. It uses propellers to move through the water. It also uses a novel combination of fishing weights and foam pool floats. These allow it to move up and down.

"The real invention here is the sensing." That's according to Dana Yoerger. He is a roboticist. He is also an engineer. He works with WHOI's Nereid. It is a ROV. It travels great distances in the arctic. It hosts a suite of sensors on board. These include acoustic sensors. It has chemical sensors. And it has biological sensors. Du was in awe of Nereid. She nicknamed her ROV Nereid Jr. Bt her vehicle has a different skill set than its namesake. "The ROV is nicely done for a 12-year-old and hers is quite clever," Yoerger adds.

The detection system is the "actually cool part." That's according to Du. She uses a high resolution infrared camera along with three different kinds of light. These spot the plastic. Du's detection methods are made up of two different wavelengths of infrared light. They illuminate the absorption spectra in microplastics. This makes them stand out from the sand. It also makes them stand out from plant life.

She also uses visible light. This spots unnatural colors. These might make the plastics stand out. (Du was also one of ten finalists in the Discovery Education 3M Young Scientist Challenge this year. You can see a demo in her application video.) The apparatus doesn't actually collect the microplastics. But it does identify where they are accumulating. She has applied for a patent. It is for the functional elements of the ROV.

"She has an impressive basic kind of engineering instinct to break down a problem like this and then go after it." That's according to Casey Machado. He is a WHOI engineer. He works with Nereid. "She was able to follow that up with the technical work, construction and design to make a working prototype. This is very cool. It's sounds simple. But it's a level of thinking that's really impressive."

Du first read about the challenge of locating ocean microplastics. It is unlike the Great Pacific Garbage Patch. Microplastics are not floating on the surface. So she knew that an ROV would be the most efficient tool for the task. Taking buckets and buckets of water samples and analyzing them in a lab would not be effective. It could never be done to the scale needed. She needed a mobile lab. It needed to find the plastics in-situ.

Du attends public events at MIT. She also goes to workshops. She has been going since she was five years old. She picked up the engineering skills necessary to build her ROV from these sessions. She got them from maker labs. These were at local libraries. She also learned from YouTube.

She says actually getting her device to move through water well was tricky. It was even hard to choose the right kind of glue. It would hold the PVC pipes together.

The ROV would flip over. This happened when she tried to move it up and down. This was before she added fishing weights. There was a lot of trial and error as she tested her ROV. She tested it in Boston Harbor.

She was asked about future plans. She said she wanted to somehow address the effects of climate change.

"Especially with climate change happening all around the world, I think there's a lot of problems that could be solved with new inventions," says Du. "Right now, I'm mainly just focusing on plastics because there's still a long way to go."

Du credits her parents for fostering and supporting her interest in STEM. They took her to MIT's student outreach activities on weekends. She says she has been able to meet students and scientists there. As a result she has her sights set on attending the university. She wants to become an engineer.

"I know I want to be an engineer because I like building things to help solve world problems," says Du. "But I'm not sure what kind of engineer I want to be yet."

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This 12-year-old girl built a robot that can find microplastics in the ocean

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Anna Du noticed plastic. It was scattered on the shoreline. She was walking along Castle Island's beach. That's in South Boston. She reached down to pick it up. She quickly realized there were many more tiny pieces. There were more than she could handle. "When I realized how many pieces there were.

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THIS EXPERIMENT REQUIRES ADULT HELP
IT DEALS WITH VERY HOT LIQUIDS
BE SMART AND BE SAFE - ONLY DO THIS WITH ADULT HELP.

You will need

A wooden skewer (you can also use a clean wooden chopstick)

A clothespin

1 cup of water

2-3 cups of sugar

A tall narrow glass or jar

What to do

1. Clip the wooden skewer into the clothespin so that it hangs down inside the glass and is about 1 inch (2.5 cm) from the bottom of the glass. (as shown)

2. Remove the skewer and clothespin and put them aside for now.

3. Get a helpful adult!

4. Pour the water into a pan and bring it to boil.

5. Pour about 1/4 cup of sugar into the boiling water, stirring until it dissolves.

6. Keep adding more and more sugar, each time stirring it until it dissolves, until no more will dissolve. This will take time and patience and it will take longer for the sugar to dissolve each time.Be sure you don't give up too soon. Once no more sugar will dissolve, remove it from heat and allow it to cool for at least 20 minutes.
NOTE: While it is cooling, some people like to dip half of the skewer in the sugar solution and then roll it in some sugar to help jump start the crystal growth. If you do this, be sure to let the skewer cool completely so that sugar crystals do not fall off when you place it back in the glass.

7. Have your friendly ADULT carefully pour the sugar solution into the jar almost to the top. Then submerge the skewer back into the glass making sure that it is hanging straight down the middle without touching the sides.

8. Allow the jar to fully cool and put it someplace where it will not be disturbed.

9. Now just wait. The sugar crystals will grow over the next 3-7 days.

Want colored rock candy? Add food coloring to your sugar water and make sure sure that it is pretty dark in color for the best result.

How does it work?

When you mixed the water and sugar you made a SUPER SATURATED SOLUTION. This means that the water could only hold the sugar if both were very hot. As the water cools the sugar "comes out" of the solution back into sugar crystals on your skewer. The skewer (and sometimes the glass itself) act as a "seed" that the sugar crystals start to grow on. With some luck and patience you will have a tasty scientific treat! Enjoy!

Science Bob

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MAKE YOUR OWN ROCK CANDY - ScienceBob.com

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THIS EXPERIMENT REQUIRES ADULT HELP IT DEALS WITH VERY HOT LIQUIDS BE SMART AND BE SAFE - ONLY DO THIS WITH ADULT HELP.

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Learn what pirates are with fun facts for kids. Find out more about the life of a pirate and improve your knowledge with DK Find Out.

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Why do we have to drink water? | Highlights Kids

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Learn why it's so important to drink enough water.