This year’s engineering school Innovation Research Grants are funding efforts to allow computers to use walls as mirrors to peer around corners, build hearing aids that better isolate sounds, and create a safe, long-lasting fire-retardant spray.

The projects number among 19 awardees of annual research grants awarded for 2022. Rodney Priestley, Princeton’s Pomeroy and Betty Perry Smith Professor of Chemical and Biological Engineering and vice dean for innovation, and postdoctoral research associate Xiaohui Xu are working to develop the fire-retardant spray, a finely tuned mixture containing polydopamine, which is similar to the proteins that help mussels cling to wood and stone. The mixture could someday be sprayed onto building materials and vegetation to prevent the spread of fire.

Many fire-retardant materials currently used in furniture and building insulation release hazardous gasses during combustion. Ammonium polyphosphate is a safer alternative, but breaks down quickly when exposed to moisture in the air. Priestley and Xu are investigating a method to combine ammonium polyphosphate with polydopamine-coated silica (a major component of sand), and spray it onto flammable materials to create a multi-layered fire barrier. An advantage of this fire-retardant material is that it can firmly adhere to the target substrate, which increases the potential for long-term protection in the environment.

Xu has tested a polydopamine-coated silica spray on cotton and foam, and found that it forms a carbon char barrier when exposed to fire.

“This is the first step. In the next step we are going to mix these nanoparticles with ammonium polyphosphate, another environmentally friendly flame-retardant material. We want to combine these to further improve the fire-retardant properties,” said Xu, a Presidential Postdoctoral Research Fellow who has also led research on a solar water purification device inspired by pufferfish.

Xu and Priestley’s work is supported by the Yang Family Fund and the David T. Wilkinson Innovation Fund.

Princeton Engineering’s Innovation Research Grants are funded by Princeton alumni, parents and other donors. This year’s awards, which total more than $1.9 million, include:

Project X Fund

Project X funding enables Princeton engineering faculty members to pursue exploratory research geared toward “creativity, tinkering and risk-taking.” The fund is made possible by G. Lynn Shostack in honor of her late husband David Gardner, a 1969 Princeton graduate. The following CBE-related projects won Project X grants:

Jonathan Conway, an assistant professor of chemical and biological engineering, for the project “Engineering auxin plant hormone-degrading bacteria for improved plant growth and productivity”;

Michael Webb, an assistant professor of chemical and biological engineering, and Hang Zhang, a graduate student in chemistry, for the project “Molecularly informed investigation of contact charging between insulating polymer surfaces”;

Helen Shipley Hunt Fund

Made possible by Helen Shipley Hunt, who earned a master’s degree in mathematics from Princeton in 1971, this fund supports research aimed at improving human health, with a focus on applied projects. From CBE, Shipley Hunt funds were awarded to A. James Link, a professor of chemical and biological engineering, for the project “Engineering hairpin peptides as a protein-protein interaction inhibitors.”

Forese, Wilke and O’Brien Family Funds

The Forese, Wilke and O’Brien families each established funds to support innovative research in human health.

These funds were awarded to Mark Brynildsen, an associate professor of chemical and biological engineering, for the project “Bacterial Jekyll and Hyde: investigating the impacts of ploidy on heteroresistance.”

Editor's note: This article was adapted from the original, which includes information on all of this year's Innovation Research Grants.