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.”