Transcending space-time with SAXS

Scientists and engineers working with the tiniest of building blocks have long endured constraints of both space and time. Namely, researchers often have to travel great distances and collect many hours of instrumental data to get a look at the nanostructures they construct. 

But that’s not the case in South Carolina these days. The University of South Carolina installed a cutting-edge Small-Angle X-ray Scattering (SAXS) laboratory in the Horizon building last year. As time constraints go, the new instrument is truly revolutionary, according to Morgan Stefik, director of the lab.

“The state of the art with SAXS has changed a lot in the past 10 years,” says Stefik, who joined the Department of Chemistry and Biochemistry as an assistant professor in 2013. “In my Ph.D., one sample required about 10 hours to measure, so you can imagine that being a pretty huge bottleneck. But with this machine it often takes just 10 minutes to get data. It’s a game changer.”

And that goes for everyone from the Low Country to the Upstate. The Columbia campus now hosts the only SAXS instrument in the state, but, through the NSF-supported South Carolina SAXS Collaborative, it's available to every researcher therein.

“There were 26 faculty in total, from 5 different universities, all with a great research need to have access to SAXS, who put the NSF proposal together,” says Stefik, who is the lead PI. “Many of them had been traveling to national laboratories to get data, which slows down your research. Now we have a shared facility that everybody has the capability to drive to, with no one more than 2 hours away.”

They don’t even have to make the trip, in fact. Stefik says that samples can be shipped and loaded by staff. The system is highly automated, with multi-sample holders that can be placed in the instrument and left to run sequentially overnight by computer. Once samples are in, the device can even be operated remotely.

For researchers who construct or study materials that have building blocks measured in nanometers, one-billionth of a meter, SAXS is a powerful analytical technique. It can readily and rapidly probe structural features on the order of 5 to 150 nanometers and, as a general-purpose instrument, even outside that range.

As part of the facility’s outreach program, students from primarily undergraduate colleges in South Carolina visit the SAXS facility every summer for an introduction to the technique and what it can do. Stefik finds that natural nanostructures can get a conversation going.

“One that’s pretty neat is we take hair from the students and put it in,” Stefik says. “Inside a single hair we find there is roughly a 10-nanometer repeat spacing. That gets the students engaged. What do you think that means? And we talk through it and consider what would it mean if there were a periodic structure inside the hair, every 10 nanometers.”

“A typical hair is about 50 microns across, or 50,000 nanometers, so that means that across one hair diameter you could fit 5,000 repeats of that structure. So your hair is kind of built like a rope, with thousands of keratin bundles acting as filaments across the width.”

Stefik is intent on creating synthetic materials with similar kinds of nanostructure complexity. As just one example, his team is working to construct an inorganic mesh with nanoscale pores that could be used to power electronics such as cell phones. By adjusting the pore size and wall thickness in the mesh to optimal conditions — and the process of finding what works best involves experimentation dependent on high-throughput SAXS data — lithium ions might be able to flow in and out so swiftly that recharging a smartphone would take just half a minute.

That’s the sort of technological promise that nanomaterials hold, and Stefik is hardly the only scientist or engineer in South Carolina aiming high. The constant hum from the SAXS instrument in Horizon is testament to that.

“Our machine does not sleep. A calendar for it is booked 24/7 at 80 percent, Stefik says. “The manufacturer tells us that we have the highest throughput install that they’ve had.”