Lehigh University 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 at Lehigh University. 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, at Lehigh University 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.

Gilchrist says he started thinking about the research project in 2016 and teamed up with Schultz. At the time, their offices were next to each other in Iacocca Hall on Lehigh's Mountaintop Campus. Their research spaces are now in the university's new Health, Science and Technology Building.

“The scientific effort is 50-50 between Kelly and me. Her science and my science are the perfect match for getting more accurate measurements for thermophoresis than have ever been done before,” says Gilchrist. “My idea was, we would approach this idea of, how do particles behave in complex fluids, in temperature gradients. My area of expertise is particle technology and transport and how things move and flow. Kelly’s expertise is in complex fluids and how to perform particle tracking microrheology.”

Gilchrist says they applied for Lehigh’s Collaborative Research Opportunity (CORE) grant and were initially denied. They applied again in 2018 and were successful, receiving a $60,000 grant from Lehigh’s Office of the Vice Provost for Research. The program is part of Lehigh’s strategy for “building a vital research portfolio that is responsive to the grand challenges of our society.”

The NSF grant followed.

The key, Gilchrist says, was showing how the research could be used to benefit mankind.

Teaming up with Cheng, who develops novel microfluidic devices for point of care and global health diagnostics, was the game changer.

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.

The development process has been very time-consuming, with weekly meetings among the collaborators from Lehigh, Tec-Masters and the Center for the Advancement of Science in Space that cover every detail and safety concern—from how hot the experiment could get to the possibility of a short circuit.

“It does take quite an effort to launch stuff into space, I’ve learned,” says Gilchrist. “It’s a complicated process. They want to be sure.”

The experiments involve 30 samples of tiny polystyrene fluorescent particles immersed in various fluids and gels and mounted on glass slides. Gilchrist says the samples will be heated on one side and cooled on the other. The microscope will track the motion of the particles to examine how they move in different temperatures. A camera in the microscope will take pictures and send them to the computer.

“You essentially remotely log in and open the software that would move the samples, turn on the microscope, turn on the heat, take images and download the images,” says Gilchrist. “It’s very much like a Microsoft Windows remote desktop environment. It’s like it’s in a lab down the hall, but it’s in space.”

Gilchrist initially envisioned himself and Ph.D. student Nazrin Hasanova ’21 as the operators of the microscope. Hasanova has worked with Gilchrist, Schultz and former postdoctoral researcher Maria Chiara Roffin for more than a year to help design the experiments and analyze data. But due to safety and security concerns, Gilchrist says, his Tec-Masters partners will likely be doing the daily login, in consultation with Gilchrist and Hasanova.

“After it gets in place, we have three weeks to run the experiments. We will be working with Tec-Masters to heat up the samples, take images and download data every night.”

Gilchrist expects he will have some interaction with the astronauts, who will have to, at the very least, set up the equipment, connect the computer to the Internet and start the experiments. “We think most of the operations will happen 4 p.m. to midnight. The astronauts sleep during that time, so there will be less vibration,” Gilchrist says.

The hope, Gilchrist says, is to have data in 2024 and then adequate time under the grant timeline to analyze the data and publish the results.

“If successful, we could continue,” he says. “If we are getting great data, we can ask to launch more samples.” 

--Story by Jodi Duckett