It took a few minutes to figure out why Mark Hersam, professor at Northwestern University (Chicago, Illinois, US) is being featured in an Oct. 21, 2014 news item on Nanowerk,
One of the longstanding problems of working with nanomaterials–substances at the molecular and atomic scale–is controlling their size. When their size changes, their properties also change. This suggests that uniform control over size is critical in order to use them reliably as components in electronics.
Put another way, “if you don’t control size, you will have inhomogeneity in performance,” says Mark Hersam. “You don’t want some of your cell phones to work, and others not.”
Hersam, a professor of materials science engineering, chemistry and medicine at Northwestern University, has developed a method to separate nanomaterials by size, therefore providing a consistency in properties otherwise not available. Moreover, the solution came straight from the life sciences–biochemistry, in fact.
The technique, known as density gradient ultracentrifugation, is a decades-old process used to separate biomolecules. The National Science Foundation (NSF)-funded scientist theorized correctly that he could adapt it to separate carbon nanotubes, rolled sheets of graphene (a single atomic layer of hexagonally bonded carbon atoms), long recognized for their potential applications in computers and tablets, smart phones and other portable devices, photovoltaics, batteries and bioimaging.
The technique has proved so successful that Hersam and his team now hold two dozen pending or issued patents, and in 2007 established their own company, NanoIntegris, jump-started with a $150,000 NSF small business grant. The company has been able to scale up production by 10,000-fold, and currently has 700 customers in 40 countries.
“We now have the capacity to produce ten times the worldwide demand for this material,” Hersam says.
NSF supports Hersam with a $640,000 individual investigator grant awarded in 2010 for five years. Also, he directs Northwestern’s Materials Research Science and Engineering Center (MRSEC), which NSF funds, including support for approximately 30 faculty members/researchers.
Hersam also is a recent recipient of one of this year’s prestigious MacArthur fellowships, a $625,000 no-strings-attached award, popularly known as a “genius” grant. [emphases mine] These go to talented individuals who have shown extraordinary originality and dedication in their fields, and are meant to encourage beneficiaries to freely explore their interests without fear of risk-taking.
An Oct. 20, 2014 US National Science Foundation Discoveries article by Marlene Cimons, which originated the news item, describes Hersam’s research and his hopes for it in more detail,
The carbon nanotubes separation process, which Hersam developed, begins with a centrifuge tube. Into that, “we load a water based solution and introduce an additive which allows us to tune the buoyant density of the solution itself,” he explains.
“What we create is a gradient in the buoyant density of the aqueous solution, with low density at the top and high density at the bottom,” he continues. “We then load the carbon nanotubes and put it into the centrifuge, which drives the nanotubes through the gradient. The nanotubes move through the gradient until their density matches that of the gradient. The result is that the nanotubes form separated bands in the centrifuge tube by density. Since the density of the nanotube is a function of its diameter, this method allows separation by diameter.”
One property that distinguishes these materials from traditional semiconductors like silicon is that they are mechanically flexible. “Carbon nanotubes are highly resilient,” Hersam says. “That allows us to integrate electronics on flexible substrates, like clothing, shoes, and wrist bands for real time monitoring of biomedical diagnostics and athletic performance. These materials have the right combination of properties to realize wearable electronics.”
He and his colleagues also are working on energy technologies, such as solar cells and batteries “that can improve efficiency and reduce the cost of solar cells, and increase the capacity and reduce the charging time of batteries,” he says. “The resulting batteries and solar cells are also mechanically flexible, and thus can be integrated with flexible electronics.”
They likely even will prove waterproof. “It turns out that carbon nanomaterials are hydrophobic, so water will roll right off of them,” he says.
A Sept. 17, 2014 Northwestern University news release congratulates Hersam on his award while describing his response to the news and providing more information about his work as a researcher and teacher (Note: Links have been removed),
The phone call from the John D. and Catherine T. MacArthur Foundation delivering the very good news was so out of the blue that Hersam initially thought it was a joke.
“Then I went into shock, and, I think, to some extent I remain in shock,” said Hersam, who received the call in his Cook Hall office. “As time has gone on, I’ve appreciated, of course, that it’s a great honor and, more importantly, a great opportunity.”
A dedicated and popular teacher, Hersam is the Bette and Neison Harris Chair in Teaching Excellence and professor of materials science and engineering at the McCormick School of Engineering and Applied Science.
“There are very few awards that provide unrestricted resources, and this one does. No strings attached,” he said. “That’s a great opportunity for a researcher — to have that level of freedom.”
Hersam is one of 21 new MacArthur Fellows recognized today (Sept. 17) by the MacArthur Foundation for “extraordinary originality and dedication in their creative pursuits and a marked capacity for self-direction.”
“I am very grateful and thankful to the MacArthur Foundation, to current and previous members of my research group and to my colleagues and collaborators over the years,” Hersam said. “Scientific research is a team effort.”
Hersam views his principal job as that of an educator — a role in which he can have more impact on unsolved problems by harnessing the minds of hundreds of young scientists and engineers.
“I love to teach in the classroom, but I also believe that scientific research is a vehicle for teaching,” Hersam said. “Research exposes students to difficult unsolved problems, forcing them to be creative. I want them to come up with truly new ideas, not just regurgitate established concepts.”
Hersam, who joined Northwestern in 2000, also is professor of chemistry in the Weinberg College of Arts and Sciences, professor of medicine at the Northwestern University Feinberg School of Medicine and director of Northwestern’s Materials Research Center.
Taking an interdisciplinary approach that draws on techniques from materials science, physics, engineering and chemistry, Hersam has established himself as a leading experimentalist in the area of hybrid organic-inorganic materials, with a focus on the study of the electrical and optical properties of carbon and related nanomaterials.
Hersam and his research lab have been working primarily with carbon nanotubes and graphene, but the support of the MacArthur award will allow the lab to diversify its materials set to other elements in the periodic table.
Earlier this year Hersam testified before U.S. Congress to push for “coordinated, predictable and sustained federal funding” for nanotechnology research and development.
The MacArthur Foundation’s website hosts a video on its ‘Mark Hersam’ webpage,
Interestingly, Hersam, in the video, describes a carbon nanotube as a rolled up sheet of graphene (it’s also described that way on the Foundation’s ‘Hersam’ webpage),
Graphene, a single atomic layer of hexagonally bonded carbon atoms, and carbon nanotubes, rolled sheets of graphene in single or multiple layers, have long been recognized for their potential applications in electronics, photovoltaics, batteries, and bioimaging.
It’s a good way of describing carbon nanotubes but the odd thing is that carbon nanotubes were discovered in 1991 (Timeline of carbon nanotubes entry on Wikipedia and in The History of Carbon Nanotubes on nanogloss.com) before graphene was first isolated in 2004 (my Oct. 7, 2010 posting).