PROVIDENCE, R.I. [Brown University] — In 2014, a team of Brown University and Rhode Island School of Design students took part in the Solar Decathlon, an international student competition to see who could design and build the most innovative, efficient and livable solar-powered home.
After two years of design and construction, the students unveiled Techstyle Haus, an energy-sipping passive house with a roof and walls made from high-performance textile materials. The house took its place among 19 other entrants on the grounds of France’s Palace of Versailles for a competition that showcased how ingenuity could drive the frontiers of sustainability. For many of the few dozen students involved, the competition became a defining moment in their educational careers. It also became a turning point for one of the students’ advisers, Derek Stein, who at the time was an assistant professor of physics at Brown.
Working with students on the project, Stein realized his expertise in biophysics could be brought to bear in solving critical problems in sustainable design and construction. In 2024, Stein retired from his professorship to dedicate himself full time to a new venture, Adept Materials, which develops sustainable building technologies based in part on his research at Brown.
Earlier this year, Adept rolled out its first consumer product, Lilypad, a paint and primer system designed to manage spikes in indoor humidity to prevent mold and deterioration of wall surfaces. In September, Fast Company named Lilypad a winner in its Innovation by Design Awards. This month, TIME named Lilypad one of its Best Inventions of 2026.
Despite his retirement from Brown, Stein maintains close ties to the University as an emeritus professor, and works closely with Brown Technology Innovations — Brown’s technology transfer office, which helps researchers commercialize inventions and discoveries — as his company continues to grow. In an interview, Stein spoke about how his research and teaching at Brown contributed to his entrepreneurial venture.
Q: How does Lilypad paint work, and what challenges for consumers does it address?
Simply put, Lilypad is a paint and primer system that absorbs excess water vapor from the air when the humidity spikes and releases it back out into the air when humidity drops. So if you’re taking a shower or doing laundry, the system helps to manage that increase in indoor humidity. The paint is able to take up excess moisture, while the primer sits behind the topcoat and helps keep that moisture from entering and accumulating inside the walls. Then when the humidity goes back down, the water is released into the air again.
Conventional paints contain fillers, which you can think of as ground-up pieces of rock that primarily add bulk to the material. What we have done is replace some of those inert fillers with desiccant materials, similar to the silica gel packets that you find in packaging that keeps your new boots or your vitamins dry. Silica gel has nanopores — tiny nano-scale holes. By incorporating them in our paint, we get the ability to absorb and safely store water. And the process is reversible, so any water that’s absorbed can also be released. We’ve shown that a gallon of Lilypad can hold and release up to a soda can’s worth of water, which is roughly how much water is released as vapor from a 10-minute shower.
This is really a way to deal with the problems associated with indoor humidity. Excess moisture contributes to aesthetic problems like peeling paint, but you can also get mold growing in walls, and that can become a fairly significant health issue. Those are the kinds of problems we’re aiming to fix.
