Joshua Brake, Harvey Mudd College – Using Light to Analyze Plants

Light can help us in a variety of ways that are still being determined.

Joshua Brake, assistant professor of engineering at Harvey Mudd College, looks inside plants to find one.

Joshua Brake is an Assistant Professor of Engineering at Harvey Mudd College in Claremont, California.

Before joining the faculty at Harvey Mudd, he received his Ph.D. and M.S. in Electrical Engineering from the California Institute of Technology (Caltech) and his M.S. and B.S. in Engineering with an Electrical Concentration from LeTourneau University. During his Ph.D. studies he developed new tools and techniques in biomedical optics to see deeper into tissue.

He enjoys teaching digital electronics because of the powerful and complex systems that can be built from a series of simple-to-understand modules. In addition to his passion for electrical engineering and optics, he enjoys working with students to hone their oral, written, and visual communication skills. When he’s not in the lab or at his desk, you’ll likely find him spending time with his wife and son, outside running in the year-round Southern California sunshine, or rooting for his favorite sports teams (New York Mets and Tennessee Titans).

Using Light to Analyze Plants

My research is in biophotonics, a field at the intersection of optics and biology.

My current project is focused on plants—with the aim to exploit the light-piping property of plant stems and roots to develop the next generation of optical tools to provide new ways to investigate plant roots and their surrounding environments.

This research was inspired by a discovery from plant biologists in the 1980s which revealed that light can propagate through plants, much like optical fibers. Surprisingly, nobody in the biophotonics community has done much with this over the past three decades, and I began to wonder, as an optical engineer, what could we do with it?

Inspired by some Star Trek science fiction, the big-picture goal is to develop a tricorder of sorts for analyzing the health of an individual plant or collection of plants in a minimally invasive way. To do this, we send light into plant roots through their stems and measure the photons that are reflected back from within the stem and roots.

The backscattered light is detected using interferometry, a strategy used in optics to amplify and measure very weak signals—our first aim is to measure a plant’s structural information like the number and length of the roots. After that, we want to explore using different wavelengths of light to tease out additional information like water content and the biochemical composition of the soil surrounding the roots in the root-adjacent region called the rhizosphere.

Ultimately, this technology could be used to help analyze how plants are growing in a field over a certain period of time since it doesn’t require that the plant to be uprooted. There are also interesting opportunities for analysis in the wake of climate-related events like droughts and wildfire where a tool like this could even be used to assess the health of the plants and soil that remain after a fire.