MP Guard: Two 14-Year-Olds Build a Coconut-Fiber Microplastic-Skimming Robot

A small robot with a large environmental target

MP Guard is a compact water-surface robot designed by eighth-grade students Brandon Miranda and Adriel Magana. Arizona State University reported on the project in April 2025 after the students demonstrated it publicly at Harvest Preparatory Academy in Yuma. Both students were 14.

The machine is roughly notebook-sized and uses a rotating mechanical skimmer to collect suspended or floating particles. A filter made from sustainable coconut-husk fibres then traps the collected material. The students' goal is to remove microplastics from waterways before those particles are ingested by aquatic organisms or dispersed further through the food web.

How MP Guard works

ASU's description allows the prototype to be broken into a clear sequence:

The project therefore combines a coarse mechanical collector with a finer fibrous filtration medium. Coconut coir is a sensible low-cost material for a prototype because it is fibrous, renewable and mechanically robust. The key unresolved question is the minimum particle size it can reliably retain at a useful flow rate.

• Movement/skimming: the robot moves at the water surface.
• Rotating cylinders and ratchet: a sharp-toothed rotating component physically intercepts particles.
• Transfer to filter: collected material is directed toward a filter stage.
• Coconut-husk fibre capture: the fibrous mat traps fine debris, with the students intending the system to collect microplastics too small to see with the unaided eye.

Built with inexpensive, accessible materials

The project is notable for its deliberately improvised construction. ASU reports that the students used a 3-D printer, duct tape, pool noodles and LEGO pieces. That component list demonstrates a design philosophy that is common in successful school robotics: use inexpensive materials to prove the mechanism first, then redesign for durability once the concept works.

The students sometimes had to wait as long as 12 hours to reprint the 3-D ratchet after design changes. Their original idea was a drone-like device that would move over the water surface, but funding constraints forced them to simplify and pivot. An intermediate idea used a common oil filter before the skimmer/filter configuration evolved.

Six months of iteration

Miranda and Magana developed MP Guard over roughly six months as members of their school's robotics club while participating in the FIRST LEGO League Innovation Project. The 2025 challenge encouraged students to propose solutions to ocean problems. Their school is in Yuma, in the Sonoran Desert, so the project also became part of an effort to connect inland Arizona students with ocean science.

When the students reached technical difficulties, school staff connected them with Vernon Morris, an environmental scientist and professor affiliated with Arizona State University. Morris provided feedback on the prototype. ASU's article places the mentorship within a broader ocean-literacy collaboration involving ASU and other science-education partners.

The March 2025 demonstration

On 13 March 2025, the students tested MP Guard in a small plastic pool in front of an audience of nearly 100 people. ASU reports that the skimmer moved, the cylinders rotated, the sharp-toothed ratchet collected particles and the coconut-husk filter trapped the material. The successful demonstration was an important proof of mechanical operation.

However, the test was not an open-ocean or river trial. The public ASU source does not provide a laboratory particle count, removal percentage, litres-per-minute flow rate or smallest verified microplastic size. Magana explicitly described future ocean testing as a goal. That distinction is important: "designed to trap microplastics invisible to the eye" describes the design intention, while a standardized particle-size efficiency curve would be needed to verify the claim quantitatively.

Patent and scale status

ASU said the demonstration showed a machine with the potential to be scalable and patented. That is not the same as reporting that a patent had already been granted or that the device had reached commercial scale. No granted patent or deployed fleet was identified in the source set used for this article.

Why a surface skimmer is both useful and limited

Surface robots can be effective for buoyant debris because they can concentrate cleanup on visible accumulation zones, marina edges, drainage outlets or river hotspots. They are also easier to retrieve and maintain than submerged systems. But microplastics do not all stay at the surface. Some polymers sink; others remain suspended through the water column or become incorporated into sediment and biological material.

Therefore, even a highly effective MP Guard-style robot would solve only one part of the microplastic problem. Its best use may be intercepting particles in specific transport zones before they disperse more widely.

Engineering questions for a next-generation MP Guard

• Particle-size efficiency: precisely measure retention at 5 mm, 1 mm, 100 µm and smaller size classes.
• Non-target capture: test whether plankton, insects, larvae or plant material are unintentionally trapped.
• Filter clogging: coconut fibre may clog quickly in algae- or sediment-rich water.
• Weather resistance: open water introduces wind, waves, UV exposure and corrosion.
• Autonomy: a practical cleanup robot needs navigation, obstacle avoidance and reliable retrieval.
• Waste handling: microplastic-rich fibre filters need controlled disposal or regeneration.
• Scale economics: many small robots may be required to treat meaningful areas.

Why MP Guard is worth following

MP Guard does not yet have the performance data needed to call it an ocean-cleanup technology at scale. The project is worth following because two 14-year-olds translated an environmental problem into a functioning electromechanical system, iterated after failed designs, changed direction when funding was limited and sought expert feedback. That process is how early engineering prototypes mature.

The next leap would be to move from a demonstration pool to controlled field trials with known microplastic concentrations and independent particle counting.

Evidence note

Evidence note: The public evidence confirms a functioning pool-demonstration prototype and details its construction. It does not provide a standardized microplastic-removal efficiency or real-ocean performance result.