College of Engineering News • Iowa State University

Four Iowa State engineering faculty receive NSF CAREER Awards

Reaching an important milestone in their careers, four assistant professors in the College of Engineering have been awarded 2009 CAREER Awards from the National Science Foundation(NSF).

The faculty honored with this highly competitive award—Dionysios Aliprantis, ECpE; Eric Cochran, CBE; Zhiqun Lin, MSE; and Qingze Zou, ME—will each receive approximately $400,000 over five years in support of their respective research and educational efforts.

“The college is very proud of our four NSF CAREER awardees this year,” says Balaji Narasimhan, associate dean of research and economic development. “These prestigious awards play a major role in launching our junior faculty’s careers since they recognize the importance of integrating cutting-edge research and innovative educational programs.”

From exploring new research on nanoscale polymer composites and structures to developing more effective scanning probe microscopes and motors and generators, their work will address a wide range of engineering challenges.

Optimizing electric machine performance

Electric machines as they currently exist may never be the same again if Aliprantis has his say about it. His project, “Sculpting Electric Machines for Unidirectional Motion,” aims to decrease the weight and size of motors and generators, as well as improve their efficiency and cost effectiveness.

“The vast majority of electric machines rotate in a single direction over their lifetime,” Aliprantis says. “Improved designs will lead to enhanced performance for the preferred direction of rotation. This research will initiate the systematic study of unidirectionally rotating electric machines.”

Aliprantis hopes to improve the performance of these machines by precisely sculpting the stator and rotor surfaces, thus affecting the electromagnetic field in the machine’s air gap. This will increase the production of electromechanical torque without compromising the machine’s electrical operational characteristics.

His methodology would allow wind turbine engineers to modify their generator designs to handle the most power possible using the least amount of materials. Similar design techniques also could be applied to machines in hybrid-electric vehicles, hybrid trains, aircraft, and ships.

Previous studies by European and U.S. researchers estimate that the use of high-efficiency motors in motor-driven systems—like the electric machines Aliprantis aims to develop—can lead to saving billions of dollars in overall economic operations and reducing millions of tons in carbon dioxide emissions worldwide. And what’s especially unique about Aliprantis’ work is that he is developing a framework to find optimal designs that can be applied to nearly any rotating electric machine type.

Investigating a new class of polymer composites

To understand the significant influence a composite can have on a structure, think of the blades in a wind power generator, which are made of carbon fibers. These carbon fibers are strong and flexible on their own, but without a matrix of polymers the fibers wouldn’t hold together.

Now, think of that relationship but on the nanoscale. That’s what Cochran is doing with the project “Block Copolymer Layered Silicate Nanocomposites: Thermodynamics, Dynamics, and Structure Property Relationships.”

As a starting point for this novel research, Cochran is looking at nanocomposites on a material with a single type of filler particle—clay. The project takes water that is naturally stuck to the surface of clay particles and replaces it with chemical groups that can cause polymers to form, essentially growing block copolymers directly from the surfaces of the clay. Ultimately, this work will provide insight into how to adjust specific parameters to develop certain types of structures.

The tough chemical structure of clay makes it a good candidate to begin research in this area. “The strength of the material can be imparted to the polymers, which will wrap each clay particle,” Cochran says. “Since block copolymers tend to self-organize, the clay particles will move with it, allowing us to precisely engineer where clay goes through synthetic techniques.”

The next level of this work is to establish what types of structures will be optimal for a specific use. One area that could benefit from this work is the packaging industry. Cochran’s work could lead to a cheaper material that adequately meets the packaging requirements of sensitive products such as electronics and medical devices.

Developing a new paradigm for creating hierarchical structures

Lin knows that controlling the spatial arrangement of components like polymers and nanoparticles can advance how new devices and materials are made. What he’s hoping to uncover with his research is how to make this control process simpler and more cost effective.

His project, “Evaporation-Driven Self-Assembly of Hierarchically Ordered Structures from Confined Solutions,” explores using evaporation as a tool for creating well-ordered structures.

Up to this point, studies have focused on creating hierarchical structures using lithographic techniques. These methods involve start-up and maintenance costs and require iterative, multistep procedures that make the structure formation process more complex and less reliable.

While Lin’s work could eliminate the need for lithographic techniques, using evaporation methods requires precise control over several factors, including evaporative flux, solution concentration, and the interfacial interaction between solute and substrate.

Overcoming these challenges would allow Lin to design hierarchical structures that consist of diblock copolymers or quantum dots self-assembled at the nanoscale. These structures would be made into multifunctional materials with unique optical, electronic, optoelectronic, and sensing properties.

“With ordered structures produced from a confined solution,” Lin says, “the fundamental scientific discoveries from this work may be applied to photonics, electronics, optical materials, magnetic materials, optoelectronics, nanotechnology, and biotechnology.”

Combining control engineering with nanotechnology and biomedical research

Over the past four years, Zou has been working to increase the speed of a scanning probe microscope (SPM) with ambitions to improve the technology as our eyes and hands to see, touch, and manipulate matters in the nano world.

His research has been delivering promising results, which is an important asset for his next project—rapid mechanical property characterization of soft materials such as DNA or cells.

The project, “Control Tools for Nanoscale Rapid Broadband Viscoelasticity Measurement and Mapping of Soft Materials,” must overcome the limitations of SPMs to work with these materials, as soft materials are dynamically evolving, making them difficult to characterize.

“Under current methods, the SPM can only measure the material viscoelasticity over a very limited frequency range, and the measurement time can be long, which generates large temporal measurement errors as the soft material itself can evolve rapidly,” Zou says. “I’m looking to new control algorithms to enable the measurement at a much larger frequency range within a much shorter time frame.” With these new control techniques, the SPM can acquire the necessary material response data quickly prior to the material’s properties changing substantially without inducing undesired spatial distortions.

The applications of Zou’s work are important in areas including biomedical sciences and nano/biomaterials. With such precise measurement capabilities, researchers can gain a better understanding of rapid nano phenomena like cell healing and dentin collagen dehydration, as well as accelerate the synthesis and design of nano/biomaterials such as biocompatible polymers for drug delivery.