Health & Medicine – Page 59

David Son uses some of the Earth’s most common building blocks to create complex new materials with potential wide-ranging applications.

Son conducts research on polymers containing silicon. One of the main elements in the Earth’s crust, silicon is the major ingredient in common sand, and is readily available.

“It’s fairly easy and inexpensive to transform silicon into compounds we can manipulate,” says Son, associate professor in SMU’s Department of Chemistry in Dedman College. “And because silicon is an inorganic element, it gives materials great stability against temperature changes and oxidation.”

Silicon-containing polymers might be used to create more heat-resistant and longer-lasting plastic materials than common organic polymers such as polyethylene or PVC, Son says. One example is the silicone ovenware widely available in stores. Pans made of silicon polymers are temperature-safe, naturally nonstick, and so flexible that they can be turned inside out to remove baked goods.

Most polymers are what chemists call the straight-chain type, with each molecule consisting of atoms laid more or less end-to-end. Son’s research focuses on a new class of polymers called dendrimers, also known as “arborols” for their molecular resemblance to trees with many branches.

The dendrimers’ structure gives them many advantages.

“You can dissolve them much more easily in solvents,” Son says. “Because the molecules are shaped like balls, they roll right over each other and don’t get tangled up the way straight-chain polymers do, so you can use them as lubricants.”

Other possible uses include new drugs in which medicines are encapsulated in the dendrimers’ branches, transported to targeted areas of the body, and then stimulated to release medication directly to those sites.

Most recently, Son has begun creating materials that merge metal ions with organic compounds called ligands. Ligands can be as simple as water or as complex as ethylenediaminetetraacetic acid, or EDTA, a compound commonly used as an anticoagulant in medicine.

Son is especially interested in how nitrogen- and sulfur-based ligands bond with silver, gold, palladium, and platinum, which are elements with well-established catalytic properties. He hopes to create compounds that can be used to improve everything from optics to plastics manufacturing.

Platinum and palladium compounds are used industrially to spark reactions in other materials. Creating better catalysts, Son says, could enable more efficient manufacturing processes, for example, at lower temperatures or with fewer defects.

Son received his Ph.D. degree in organic chemistry from MIT and has conducted research at the Argonne National Laboratory and the Naval Research Laboratory.

The movement of aquatic life can appear inexplicable when viewed through the glass of an aquarium tank.
But Paul Krueger believes the mechanics that jellyfish and squid use to maneuver can be applied to technology in the emerging field of “micro” vehicles.

Krueger, associate professor in the SMU Bobby B. Lyle School of Engineering‘s Department of Mechanical Engineering, is studying a mechanical system similar to that used by jellyfish and squid to understand pulsatile propulsion and apply it to exotic engineering applications like micropropulsion. Krueger’s research results eventually might propel tiny vehicles — sizes of a centimeter, millimeter or smaller — used in microsurgery, create micro-submarines for undersea caverns exploration, or maneuver small aircraft for military surveillance.

“Small flight-capable or submersible vehicles are of great technological interest because their diminutive size permits increased portability and access to otherwise inaccessible locations,” Krueger says.

Creating new propulsion schemes is “paramount to the design of micro vehicles because traditional propulsion designs, such as propellers and steady jets, become too inefficient at small scales,” he says.

Krueger believes that pulsed jets, consisting of a series of jet pulses with no flow between them, is a promising approach to developing micropropulsion capability. He plans to develop a model system that propels itself using pulsed jets generated by a volume-displacement mechanism. The behavior of this representative vehicle will help reveal how to adapt pulsed jet propulsion for small-scale vehicles.

Krueger’s research is being supported through a five-year, $400,000 Faculty Early Career Development award from the National Science Foundation, partially because of its multidisciplinary nature and potential for educating pre-college students.

As part of the research, he is collaborating with a biologist who is an expert on squid biomechanics, enhancing cross-disciplinary efforts between the fields of biology and mechanical engineering.

Krueger also plans to incorporate the study of micropropulsion devices and its applications to biology, marine life, and medical applications into introductory material for mechanical engineering courses.

“Illustrating applications of mechanical engineering in different fields may be a key factor in attracting new students from various backgrounds to study mechanical engineering,” he says.

Krueger joined the SMU Lyle School of Engineering in 2002. He received his B.S. in mechanical engineering in 1997 from the University of California at Berkeley. Krueger received his Ph.D. in aeronautics in 2001 from the California Institute of Technology.