Pro­fessor of Chem­istry Mark Nussbaum spent the fall semester on sab­batical at Col­orado State Uni­versity,
devel­oping small microfluidic devices that allow for portable chemical analysis. Mark Nussbaum | Courtesy

Pro­fessor of Chem­istry Mark Nussbaum’s sab­batical at Col­orado State Uni­versity allowed him to hike out­doors in the Rocky Moun­tains almost every weekend — some of the same types of envi­ron­ments where his research devices may someday be used.

Nussbaum per­formed ana­lytical chem­istry research in the area of microflu­idics in Charles Henry’s lab, the chair of the department of chem­istry at Col­orado State Uni­versity, alongside Henry’s group of 20 graduate stu­dents.

“Dr. Nussbaum is the third faculty member in 15 years that has done a sab­batical with me,” Henry said in an email. “I also typ­i­cally have one to three vis­iting grad stu­dents from uni­ver­sities around the world. While Mark was in the lab, there were stu­dents from Brazil and Thailand.”

Nussbaum reached out to Henry, who said he has been actively researching in the field of microflu­idics since 1998, after Nussbaum had famil­iarized himself with Henry’s work.

Microflu­idics con­sists of devel­oping small devices for trans­porting and mixing small amounts of solu­tions in order to find any chemical signal that would indicate the presence of a chemical marker of interest. These devices have numerous pur­poses.

“The goal is to make devices that people can use outside of a lab­o­ratory setting so that there is some­thing you can more easily take into a third-world country or a rural place, so that you can do envi­ron­mental or medical diag­nostic testing,” Nussbaum said.

Nussbaum worked in two areas of microflu­idics: paper-based and small plastic devices. The former, also referred to as a lab-on-a-chip, resembles an elec­tronic chip equipped with channels for chemical reac­tions to occur. A desired sample is added, whether it be blood, urine, or water, and a color change or other indi­cator denotes that a key diag­nostic marker like a spe­cific protein, small mol­ecule, or metal ion is present in the sample.  

“You can imagine some­thing like litmus paper, but much more sophis­ti­cated,” Nussbaum said. “You can modify the paper by putting channels directing where liquid will flow and mix. One easy way to do that is through wax printing.”

Wax printing involves placing thicker paper into what looks like a standard com­puter printer, which then prints designs with wax rather than ink. The wax then sinks through the paper when exposed to heat, cre­ating a 3‑D barrier to water or another aqueous solution of chemical or bio­logical reagents.   

Nussbaum said Henry’s research group is doing a lot with paper-based microflu­idics, pri­marily as a way of testing for markers of certain dis­eases or looking for envi­ron­mental con­t­a­m­i­nants in water or air using the devices.

“There are some dis­eases that are espe­cially prevalent in third-world coun­tries that could be more easily diag­nosed if the patients had access to lab facil­ities to do chemical diag­nostic tests,” Nussbaum said. “Instead of having the space available, it would be easier to make some of these small devices and have them available to diagnose dis­eases like sal­mo­nella or other bac­terial infec­tions.”

Nussbaum also said there can be problems with paper-based microflu­idics: Solu­tions don’t always mix quickly on paper, and the devices are less repro­ducible than desired. In response to these chal­lenges, he also helped develop some small plastic devices made using 3‑D printing.

“You could put a solution in one part of the device and then flip it over so that the fluids would mix instan­ta­neously, so you would have a lot of simul­ta­neous mixing of solu­tions,” Nussbaum said. “We call it ‘mix-bricks,’ kind of like Legos you would make solu­tions in and then attach together to improve mixing.”

This was not the first or last time Nussbaum will work with microflu­idics, he said.  Nusbaum did some microflu­idics research using dif­ferent mate­rials during his last sab­batical at Ireland Uni­versity College Cork, and said he plans to guide some of his stu­dents at Hillsdale in imple­menting their own research using microflu­idics with these new tech­niques.

Dean of Natural Sci­ences Christopher Van Orman said it is important for pro­fessors to go on sab­batical for this very reason, and said some of his own sab­bat­icals included trav­eling both to the Uni­versity of Michigan and the Stanford Syn­chrotron Radi­ation Lab­o­ratory.

“Sab­bat­icals help to maintain the quality of edu­cation that is pro­vided to our stu­dents,” Van Orman said.

Nussbaum said he will write an article based on his fall research and plans to con­tinue col­lab­o­rating with Henry in the future.

Nussbaum said devel­opment with microfluidic devices as a means for diag­nosing disease is still in its ear­liest stages. He said it is hard to develop some­thing simple and inex­pensive when con­di­tions like poor water quality or heat could make it hard for a device to be effective.

There are existing devices used, such as test kits for testing water pol­lu­tants, but the pro­to­types from some com­panies are not as user-friendly.

“If it involves beakers, it isn’t quite what we want,” Nussbaum said. “We want some­thing simpler.”