Hillcrest High's Mobile Microplastic Purifier: A Boat-Shaped Cleanup Prototype for Rivers and Lakes

What the students built

The Hillcrest team developed a portable, boat-shaped microplastic purification system intended to move between lakes, rivers or other bodies of water. That mobility is central to the concept: instead of constructing a fixed treatment installation at each site, the students wanted one platform that could be transported and redeployed.

The 2025 Tim Draper High School Utah Entrepreneur Challenge described the device as combining reverse osmosis, semi-permeable membranes, organosilanes, a high-speed suction intake pump and solar energy . Local reporting focused on the boat-shaped prototype's semi-permeable membranes and organosilane chemistry, which were intended to trap or chemically fix microplastics so that a suction system could collect them.

What are organosilanes doing in a microplastic purifier?

Organosilanes are silicon-containing molecules used to modify surfaces. Different silane groups can make a surface more hydrophobic, hydrophilic or chemically reactive. In a microplastic-removal concept, a tailored surface can be designed to interact more strongly with plastic particles than untreated material does.

The Hillcrest project materials say organosilanes help "chemically fix" or neutralize microplastics. Public sources do not disclose the exact silane chemistry, coating process or binding capacity. This is an area where the team's future technical publications would need to distinguish between three possible functions: making particles adhere to a surface, aggregating them into larger structures, or chemically altering their surface enough to make downstream filtration easier.

The engineering system

Local reporting describes a prototype that required much more than a filter cartridge. The students learned to solder motor wiring, program an Arduino, connect a Raspberry Pi, create an application for the prototype and use 3-D printing. The group reportedly spent about three months building and troubleshooting the system, often working on weekends.

The prototype's key subsystems can be understood as follows:

• Mobile hull/platform: allows the device to be deployed on open water.
• Suction intake: moves contaminated water through the collection system.
• Semi-permeable membrane stage: separates particles according to size/transport behaviour.
• Organosilane-treated components: intended to improve microplastic capture.
• Electronics: Arduino and Raspberry Pi components support control and the team's app.
• Solar-energy concept: the official 2025 competition description lists solar energy as part of the design.

Testing and iteration

The team did not begin with an open-water field trial. According to the Midvale Journal, one early practical test took place in a bathtub to check the suction system. The group went through multiple design failures, rewiring and reprinting parts. That is a useful detail because it shows the device was a genuine prototype under iteration rather than only a presentation concept.

At the same time, the public sources reviewed here do not provide a controlled removal-efficiency percentage, litres-per-hour throughput, particle-size distribution, membrane fouling rate or field performance in a real lake or river. The award recognizes the quality of the entrepreneurial prototype and pitch, but it should not be treated as proof that the purifier is already capable of large-scale environmental remediation.

The 2025 competition result

The Lassonde Entrepreneur Institute at the University of Utah recorded "Microplastic Purifier (Hillcrest High)" as the second-place winner of the 2025 Tim Draper High School Utah Entrepreneur Challenge. The team received US$5,000 for second place and also won the US$500 Top Online Vote Award. All top-20 finalists received additional finalist awards and were offered places in the Lassonde Founders programme, including housing-scholarship support.

• Second place: US$5,000
• Top Online Vote Award: US$500
• Finalist award: US$100 for each finalist team under the competition structure
• Lassonde Founders offer: Top finalists offered programme participation and housing scholarship support

The project predates the award year

A Devpost page titled "Microplastic Purifier," created by Sashwath Narayanan and Om Sanghvi, shows the project being submitted in August 2024 to several hackathons. That page already mentions organosilanes, a suction mechanism and reverse osmosis. This matters for historical accuracy: it is better to describe the device as a project that developed through 2024 and achieved major recognition in 2025 than to imply that every element was invented for the first time in 2025.

Follow-on work in 2026

Hillcrest students continued working on microplastic-related entrepreneurship. In February 2026, a different Hillcrest project called MCAP won the US$10,000 grand prize in the 2026 Tim Draper High School Utah Entrepreneur Challenge. MCAP is a bottle-cap system intended to filter microplastics and nanoplastics from drinking water. Sashwath Narayanan was publicly identified with that team.

MCAP should not be confused with the 2025 boat-shaped purifier: it is a separate follow-on concept. The connection is useful because it shows that at least some of the students continued developing water-pollution solutions after the 2025 award.

Technical questions that determine whether the boat concept can scale

• Capture rate versus water volume: open-water cleanup needs very high throughput because microplastic concentrations can be low and dispersed.
• Membrane fouling: algae, silt and organic matter can rapidly clog fine membranes.
• Selectivity: the system should avoid removing excessive plankton or other useful biological material.
• Organosilane safety: coatings and reaction products must remain stable and non-toxic in aquatic environments.
• Energy balance: pumping and propulsion energy must be compared with the amount of pollutant removed.
• Waste handling: collected microplastic material requires safe storage and disposal.
• Weather and navigation: a small prototype must be redesigned for waves, wind, debris and collision risk.

What the project combines

The Hillcrest purifier tries to bridge two very different fields: water-treatment chemistry and mobile robotics. Fixed treatment plants can process huge volumes but only at a fixed location; autonomous or portable surface systems can move to hotspots but have much smaller treatment capacity. The students' idea is to make the treatment stage itself mobile.

The project's next scientific milestone would be a transparent field test reporting exactly how many particles, what size range and what mass of plastic the device removes per hour in real water. Until such data are available, the 2025 purifier is best understood as an award-winning functional prototype and entrepreneurial engineering project.

Evidence note

Evidence note: No peer-reviewed or independently verified microplastic-removal efficiency for the 2025 Hillcrest mobile purifier was identified in the public sources used here. Competition success demonstrates innovation and entrepreneurial promise, not regulatory water-treatment validation.