• Professor A. John Hart with a folding paper cylinder. Paper's ability to fold and unfold many times and retain its integrity is a motivation for Hart's work on origami-inspired engineering.

    Photo: Denis Paiste/Materials Processing Center

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Faculty highlight: A. John Hart

Mechanical engineering professor explores the science and technology of nano manufacturing.

Associate Professor of Mechanical Engineering A. John Hart hopes progress in the science and technology of micro and nano manufacturing will enable new technologies in such areas as consumer electronics, medical devices, and arts and crafts.

"Being in mechanical engineering, in the area of manufacturing, I feel especially motivated to do things that can make a practical impact in how materials are made and how everyday things are improved," Hart says.

His expansive interests include carbon nanotubes and graphene, 3-D printing and other additive manufacturing processes, and origami-inspired engineering. He is also interested in using nanoscale and microscale structures as media of art and communication. His "Nanobama" microscopic faces of Barack Obama, created in 2008, were noticed by newspapers from Japan to Eastern Europe and drew attention from the White House. The tiny carbon-nanotube images of President Obama were made from patterned carbon nanotubes and imaged using a scanning electron microscope.

Hart, who received his PhD at MIT in 2006, returned to MIT from the University of Michigan last July to join the MIT faculty. His Mechanosynthesis Group, which has straddled the two campuses during an 18-month transition, has already grown to 17 members at MIT. Recent projects, undertaken at both Michigan and MIT, include:

  • The Robofurnace, an automated system for high-throughput synthesis of nanomaterials, including carbon nanotubes (see ‪related article on graduate student Ryan Oliver)
  • Understanding of the role of chemical and mechanical coupling in carbon nanotube forest growth (see related article on postdoctoral associate ‪Mostafa Bedewy)‬‬
  • High-speed self-assembly of colloidal systems, in both 2-D and 3-D
  • A new concept for direct-write printing of solid particles at small scales, funded by the Deshpande Center at MIT
  • Exploration of the folding mechanics of paper, and design principles for achieving folding of paper into small-scale engineered surfaces and structures

The Robofurnace project, which has its own website and Twitter feed, is being rebuilt at MIT with improved mechanics. "With our combined expertise,” Hart says, “we decided to simply take an engineering approach, an off-the-shelf furnace, and mechatronic hardware to achieve two objectives: one, to build a machine that could help out the researcher by increasing the number of experiments that he or she could do per day, and two, to enable improved control via the use of automation. I wouldn't say it's a breakthrough scientifically or technically, but it's inspired by a perspective on what tools we can build to improve the outcomes and the pace of our research and to use automation to discover hidden factors in the process."

Hart envisions a day when multiple labs will have automated systems like Robofurnace, automatically sharing data and using software-driven analysis.

Hart was assistant professor of mechanical engineering, chemical engineering, and art/design at the University of Michigan from 2007 through June 2013. "I had a great time as a faculty member in Michigan, but it was a wonderful opportunity to come to MIT,” Hart says. “I'm motivated to be the best group leader and mentor that I can be, and to chart a vision toward important new materials and manufacturing technologies."

His team at MIT includes three former Michigan students who became MIT students, as well as two continuing Michigan students who are visiting at MIT, Ryan Oliver and Sei Jin Park, and seven new MIT graduate students recruited last year. Work on origami-inspired manufacturing is led by graduate students Abhinav Rao and Megan Roberts, and digital printing is led by doctoral candidate Justin Beroz. This semester, Hart is teaching 2.S998, a new graduate class on additive manufacturing, with graduate student Jamison Go as lead teaching assistant. Hart also plans to teach a professional short course on 3-D printing and additive manufacturing this summer.

Work in the group is supported by several companies as well as the National Science Foundation, Air Force Office of Scientific Research and Office of Naval Research, National, and the Deshpande Center at MIT. The group is affiliated with the MIT Department of Mechanical Engineering, the Laboratory for Manufacturing and Productivity (LMP), Microsystems Technology Laboratories (MTL), the Materials Processing Center (MPC), the Center for Graphene Devices and Systems, and the MIT Energy Initiative (MITEI).

Additive manufacturing, also called three-dimensional printing, has made an impact in markets as diverse as medical and dental products, such as Align Technology's Invisalign-brand clear thermoplastic braces, and jewelry from sites such as MakerBot, Etsy, and Shapeways. Airplane makers are using 3-D printing to produce lighter, stronger parts using computational design and taking advantage of the geometric flexibility of the additive process. Airbus, for example, is adopting a metal 3-D printed jet-engine hinge that is half the weight of the part it replaces.

Additive-manufacturing revenues hit $2.2 billion worldwide in 2012, but Hart says the most significant growth is yet to come. "By their nature, additive methods such as 3-D printing are not going to replace high-throughput manufacturing operations,” he says. “For example, if you wanted to make a large quantity of this remote control on my desk, or something else, out of plastic, injection molding, for example, would continue to be a more scalable method because of what governs the physics of the process. Nevertheless, the emerging capability to print pretty much any shape you want, with some limitations, out of plastic and other materials, means that we can think of the small-volume manufacturing of a variety of customized objects and products. These can range from everyday convenience objects such as phone cases to lifesaving objects enabling new medical treatments. For example, I see emerging examples where custom medical implants can be printed from scan data of the patient."

Although he's keeping details under wraps, Hart says his group is working on improving additive manufacturing at small scales, where materials could be polymers, metals, or semiconductors. "I'm also interested in innovative concepts for macroscale additive manufacturing,” he says. “How do you make the process of 3-D printing a polymer or a metal 10 or 100 times faster, or how do you make the cost one-tenth of the current cost?"

Because the new additive technologies are more deployable by small shops, they could open new markets for locally made, customized products. "It will be interesting to see how that affects the dynamics of craft fabrication and localized manufacturing, enabled by digital sharing of designs," Hart says. "If you want to get something made, if the process to make it can be completely digitized, does it matter where it's made or who makes it?"

Hart also is exploring paper folding as a model for using folding as a tool to transform materials into novel structures with functionality. The NSF-funded origami project is a collaboration with researchers at the University of Michigan. "It's also one of these areas at an intersection where I hope our expertise can be useful," Hart says. "Paper is an amazing material, but what if you could make papers out of other things, paper-like materials, and what if you figure out how to, in a real engineered way, fold things at a wide range of scales?"

Demonstrating a set of complicated folds on a typical letter-size sheet of paper, Hart asks: "If instead of being 10 inches on a side, or 100 millimeters on a side, what if I want it to be 1 millimeter on a side? How in the world do I fold it up like this? I'm not going to do it with my hands; I'm not going to do it with a little robot. I have to program that functionality into the material itself. I'm not saying what it might be useful for, but let's just think about the process and if it could be made out of a novel nanostructured material with optical functionality or energetic functionality. I think that's really interesting also because of the versatility of folding as a transformational process. It's easy to make things in sheets at very high speed and to pattern them in 2-D. It's much harder to build in 3-D, but transformation by folding presents a new opportunity. If you can bring to bear the materials manufacturing process and then mathematics of the performance of the material, then I think there can be a real interesting convergence."

Topics: Carbon nanotubes, Faculty, materials, Mechanical engineering, Materials processing

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