Lehigh Professors to Conduct Experiments in Space to Study Thermophoresis

Gravity is the force that keeps us tethered comfortably to the earth. It influences multiple physical, biological and chemical phenomena, helping to keep our bodies and our planet in working order. But the effects of gravity can sometimes hinder scientific discovery.

That’s the case for James Gilchrist, the Ruth H. and Sam Madrid Professor of Chemical and Biomolecular Engineering. His solution? Send his experiments into space—specifically, to the International Space Station, where there is no gravitational pull.

Gilchrist, along with Kelly Schultz, associate professor of chemical and biological engineering, and Xuanhong Cheng, professor of bioengineering and materials science and engineering, received a $400,000, four-year grant in 2021 from the National Science Foundation (NSF) and the Center for the Advancement of Science in Space (CASIS), which is the manager of the International Space Station orbiting laboratory.

The grant is to study “Thermophoresis in Non-Newtonian Fluids for Bioseparations.” Thermophoresis is a natural phenomenon in which a temperature gradient causes particles to migrate. It is used to separate molecules within a sample and could provide a way to detect the presence of disease in bodily fluids.

But the problem is that temperature gradients cause a change in fluid density, and gravity takes over, causing the fluid to stir. The experiment detects the fluid flow, not the movement solely due to thermophoresis. Gravity, then, limits the detail of the data that can be extracted.

Sending the experiment into space will leverage microgravity conditions to advance fundamental understanding of the movement of particles through liquids and gels, says Gilchrist. The understanding will help advance science in practical ways—such as helping to detect viral load.

He explains:

“Let’s say you go to a Japanese restaurant and get a bowl of miso soup. It’s mesmerizing. When it’s still hot, all the ingredients are swirling around. The liquid inside the bowl is hot, and because it’s hot, its density is lower, and the hot fluid rises and colder fluid near the surface falls, and recirculation ensues. But we want to study how the particles move due to the temperature gradient, not the fluid flow.

“The only real way around that is to reduce the impact of gravity because the change in density doesn’t result in buoyancy in microgravity,” he says. “There’s no recirculation.”

The space mission’s code name is TABOOS, which stands for Thermophoretic and Brownian Optical Observation System.

The team’s “lab in a box” launched Aug. 1 from Northrop Grumman’s Mid-Atlantic Regional Spaceport on Wallops Island in Virginia. It will be part of the payload of the NG-19 Cygnus spacecraft aboard an Antares rocket. NASA contracts with Northrop Grumman and SpaceX for resupply missions.

Gilchrist says the lab experiments are scheduled to be launched in mid-December on NG-20 and he plans to view that one in person.

“I want to see it go up,” he says.

Cheng invents devices that separate viruses in order to detect viral loads from biological fluids and natural samples. “This is necessary to monitor infection and the environment,” Cheng says, adding that the research will generate fundamental knowledge about thermophoresis that will aid in the development of viral separations.

Cheng, working with the Office of Creative Inquiry at Lehigh, takes undergrad students to Sierra Leone in West Africa over the summers to learn about the healthcare challenges of the people there.

Knowledge gathered from fundamental research could inform Cheng’s work on devices to help improve public health in resource-limited countries, Gilchrist says.

Gilchrist and Schultz have spent the last two years working with Huntsville, Ala.–based Tec-Masters, Inc., to develop the lab equipment for their experiments, which includes a compact microscope with a camera and a computer. Tec-Masters specializes in “systems engineering services for flight payloads, including design, development, prototyping and digital engineering,” according to its website. The equipment will also be used for unrelated research by another university, Gilchrist says.