Going with the Flow

What do tweezers made of light and phones that check your cholesterol levels have in common? Besides sounding like stuff from a science fiction novel, they also happen to be technologies developed by David C. Erickson, associate professor of Mechanical and Aerospace Engineering. While his research projects and inventions seem to span an unusually broad range of fields, they all tie into Erickson’s fascination with light and fluid dynamics on a nanoscale level. By exploring these two fundamental forces at the finest detail, Erickson is looking to change the way we use technology in our daily lives. “I’m an engineer,” says Erickson. “And as an engineer, my goal is to understand science and apply it to very specific problems. I like to drill down on specific applications, and find a way to contribute to addressing those issues.”

Fluid Mechanics: From Biggest to Smallest

Erickson originally hails from Edmonton, Canada, a city at the heart of the oil and gas industry that dominates the area. “Almost everyone there worked in the oil industry, at one level or another. My parents, our neighbors, it’s just what you did,” he says. Those who were mathematically and technically inclined would go to the University of Alberta and get engineering degrees, which is exactly what Erickson did. Through a series of co-op job experiences, however, Erickson quickly learned the field wasn’t for him. “We would be working in the extreme conditions of Alberta, sometimes it was minus-forty-degree weather,” he says. “I was the youngest guy there, so they’d put me on the bottom floor of the operation. We’d start at 8 AM and by 10 AM I’d have to go shower off because I would be covered in a coating of oil pitch by then. So it was after these experiences that I decided this was not the right career path for me.”

Erickson left the oil industry for a Ph.D. program at the University of Toronto, also in the field of mechanical engineering—but with a focus in nanotechnology. “I went from working in the biggest fluid mechanical industry in the world to the tiniest,” says Erickson. There, his graduate research focused on the fluid mechanics of molecules through very tiny channels, and investigating how these fluid dynamics coupled with chemical reactions. “We ended up with some tools that allowed us to effectively model these systems, and some new ways of speeding up chemical reactions,” says Erickson. He went on to the California Institute of Technology to do a post-doc, where he learned how to further develop ways of integrating fluid mechanics with electronics to make new types of technologies. “I got a nice picture of how to solve problems,” says Erickson.

Building Better Tweezers He began putting those tools to use when he accepted a faculty position at Cornell in 2005. Specifically, he began building new types of optical devices that can manipulate extremely small pieces of matter, including organic molecules such as DNA, or inorganic particles. These devices improved upon optical tweezers, which are laser-based instruments that harness the light’s inherent attractive and/or repulsive forces to trap and manipulate particles that are on the scale of several micrometers to a few hundred nanometers in size.

Erickson and his team began investigating ways to push the boundaries of this technique so that they could handle much smaller objects. This requires the optical tweezers to have a much stronger trapping capability, however. To accomplish this, they created waveguides (tubes that transport the light for manipulating the objects) which leak a super-strong evanescent field of light, like a halo, which was even more effective at both trapping and transporting nanoscopic objects as small as 60 nanometers. Thus, previously ‘untrappable’ objects, such as DNA, proteins, carbon nanotubes and quantum dots, were suddenly able to be trapped and examined using Erickson’s technology.

“He was the first one to use waveguides to manipulate nanoscale objects in solution,” says Bernardo Cordovez, who was Erickson’s first graduated Ph.D. student, and now colleague. “With that work, he and his group were able to break a fundamental physical barrier that had plagued optical manipulation researchers for decades, and opened up a new realm of possibilities in the control and analysis of nanoscale objects.”

This breakthrough led to the founding of a start-up company, Optofluidics, Inc., (of which Erickson is chairman, and Cordovez is now CEO). The company was named the Philadelphia Life Science Startup of the year in 2012 by the Philadelphia Chamber of Commerce, has won an IEEE corporate innovator award, and its technology (dubbed ‘Nanotweezer’) was named best new product silver award at the PITTCON 2013 conference. “They’re doing well,” says Erickson, “They’re generating revenue, with sales coming from Europe and China—their customers are a mix of research labs and industry players.” Cordovez is happy to have Erickson involved in the venture. “His input as the technology's creator is invaluable,” he says.

Bringing Microfluidics to Mobile Health More recently, Erickson’s lab has focused on a new application of their research—mobile health. “We started looking at things more on the applied side—to try to solve real problems,” says Erickson. He arrived at the idea of creating medical diagnostics for smart and mobile phones. Currently, the diagnostics that are available to people to use in their daily lives are typically glucose meters and pregnancy tests, Erickson explains. Both are easy to market; pregnancy tests are simple, only needing to give a binary, yes or no result, while glucose meters are used three times a day to check blood sugar levels, making it a profitable product for the company that sells them. “The vast majority of other diagnostic scenarios don’t fall into those categories,” says Erickson. Take, for example, cholesterol levels. The test must reveal a number, not a yes or no answer—and it only needs to be administered once in awhile, meaning it wouldn’t yield large profits for the company making the tests. “But, if you make those measurements on your smartphone, it dramatically reduces the barrier to entry,” Erickson says. “Now, you have this device that everyone’s carrying all the time—it has connectivity, and you’re already trained on how to use it, since everyone already knows how to use their smartphones, and all apps are designed to function in essentially the same way...so we recognized that, and saw a good possibility for a science and business opportunity.”

Erickson’s group has begun developing a device that uses this modern-day phenomenon, combining it with their developed microfluidic components and photonic technologies, so that any smartphone can be equipped with a small device that fits over the phone’s camera. Users obtain a blood sample using a simple finger stick, and insert the disposable chip with the sample into the analytical device on the phone. The optical interrogation technology processes the sample and the smartphone then displays the diagnostic results to the user on the app, along with information about optimal levels and suggestions for treatments. Currently, they’re developing the technology to be able to read micronutrient levels, vitamin deficiencies, cholesterol levels, and blood disease factors.

The technology could be useful for users in the U.S., where roughly 75% of people are vitamin D deficient and 60% have high cholesterol. It also holds significant promise for developing countries, where mobile phone use is on the rise along with nutritional deficiencies such as vitamin B12 in India. The tool has garnered widespread interest, as well as funding—in August 2014, the project was awarded a $3 million grant from the NSF.

Erickson is also investigating other health-related applications of his technology—specifically, developing cheap, mobile PCR machines that can run on solar power. PCR machines are devices used to amplify DNA samples, and are often used to conduct diagnostic assays or screen for bacteria or viruses. These machines typically cost thousands of dollars, and require a significant amount of energy to function. Thus, Erickson’s team is working on developing a solar-powered PCR machine that requires nothing but sunlight to run these key diagnostic tests. “This will enable you to do diagnostic testing in the absence of infrastructure,” he says. This capability could change health screening in remote areas, and the team has already conducted initial trials in Kenya and Uganda, where they have been able to run tests for a type of cancer called Kaposi’s Sarcoma, which is caused by a virus and can opportunistically infect people with AIDS. Thus, it is one of the most widely reported forms of cancer in certain areas of Africa.

As Erickson’s team’s research moves forward into this new frontier of technology, it seems evident that the work will follow along the same path of success that Erickson has previously forged with his work in optofluidics. “I think David really has the opportunity to train his students to not only create new products, but to create products in a category that didn’t exist only five years ago,” says Matthew Mancuso, a recent Ph.D. graduate from Erickson’s lab who currently works at LEK Consulting, a global management consulting firm. “David practices what he teaches, and constantly improves, keeping himself an amazing example of what you can achieve when you work hard.”