A hot glue gun stick has more uses than gluing fabric material together or working on an arts and crafts project. Jonathan Felts, a fifth-year Ph.D. candidate in MechSE, explores the functionality of polymer—the material in hot glue—at the nanometer scale.
“Polymer technology is going to be very big in the future because it is lightweight, flexible and can possess many of the optical and electrical properties found in materials currently used for most consumer electronics,” Felts said.
Felts is a Department of Energy Office of Science Graduate Fellow (DOE SCGF) who noted that he developed his nanotechnology project from the financial support and overall flexibility that came from the fellowship’s stipend. With help from MechSE professor William P. King, Felts uses nanometer sharp atomic force microscope (AFM) tips as a tool for nanomanufacturing.
“The AFM employs a microcantilever beam with a nanometer sharp tip attached to the end, much like a small record player stylus, to interrogate samples at the interface between the sharp tip and a surface,” Felts explained.
Conventionally the AFM was designed to measure nanometer-scale surface topography, but it has been expanded to measure and modify materials in a wide variety of ways throughout the last 25 years. Felts works with AFM tips that have heaters built into the free end, allowing him to apply very localized heat to surfaces.
“Now we have a 10 size nm hotspot,” Felts said. “Every process on the planet somehow depends on temperature, and we can explore and exploit this temperature dependence at the nanometer scale.”
Felts turns the hot AFM tip into a hot glue gun by coating it in polymer. When the tip gets hot, the polymer on the tip melts and flows onto a surface. Controlling the tip temperature while scanning the tip along a surface provides a method for patterning polymer at the nanometer scale.
According to Felts, his interest in nanotechnology began when he found a book on the topic during his freshman year of undergraduate classwork at Georgia Tech.
“I was quite fascinated with the idea of controlling processes at the nanometer scale,” Felts said, “But I wasn’t ready in my first year of undergraduate to commit to attaining a PhD to work on the subject. Sophomore year, I decided to do a co-op for General Electric [GE]. I decided that if I didn’t love my co-op job, I would go to graduate school to pursue my original fascination with nanotechnology.”
After two semesters of working with GE, he decided to apply to graduate school.
“I wanted to be at the forefront of technology,” Felts said. “I decided to go into nanotechnology because I wanted to work on something interesting and challenging.”
After applying to several schools to continue his education, Felts said he received a call from Professor King—formerly a professor at Georgia Tech—who asked him to consider Illinois for his higher studies.
“He had a pretty good answer for me for every concern I had about choosing Illinois over Georgia Tech or any other school,” Felts said. “He made a strong case for Illinois, and his research closely aligned with my interests.”
Felts looks forward to using his research on atomic force microscopes and working with polymer technology to further improve nanomanufacturing. There are many emerging nanolithography techniques—including heated-tip-based nanomanufacturing—that are well suited for patterning chemistry at the nanometer scale. Although a lot of effort has gone into patterning chemistry at the nanometer scale, very little research has focused on measuring the chemical composition of the patterned chemistry.
“Usually to measure chemistry, you have to look at the materials’ interaction with light, which is difficult to do at the nanometer scale because the light wavelengths are hundreds of nanometers to microns. These light wavelengths are relatively large compared to the structures we are trying to measure,” Felts said. “It’s very hard to confine the light to such a small point to achieve nanometer scale resolution.”
Felts further worked with the atomic force microscope and discovered that he can measure nanostructure expansion when they interact with infrared light. Polymer absorbs infrared light, causing it to heat and expand, which an AFM tip can detect, providing a method for nanometer scale infrared absorption measurements.
“You can measure the chemistry at the nanometer scale, which is an important capability as nanomanufacturing matures enough to produce an actual product,” Felts said.
As for the future after his PhD degree, Felts said that although he wants to pursue work in the labs, he is still passionate about teaching. At Illinois, he has taught both intermediate heat transfer and conduction heat transfer class for two semesters while the professor was gone.
“When the professor was out of class, he let me teach the class,” Felts said. “I showed up about a dozen times a semester and gave a lecture.”
For now, Felts’ goal is to conduct postdoctoral research in a federal lab. Then he plans to build on his professional research experience, from where he hopes to return to academia.
“I do love teaching,” Felts said. “But I would like to build up my research career first, and then return to the classroom when I am ready.