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Nanofoams for Better Body Armor, Layers of Protection for Buildings

Nanofoam at 50-micron scale
Nanofoam at 20-micron scale
Nanofoam at 5-micron scale
Nanofoams made from porous silica, with an average pore size of a few microns, seen at the 50-micron, 20-micron and 5-micron scale. Engineers are developing nanofaoms that disperse the force of an impact over a wider area than conventional foams.

Porous nanofoams might be the future of body armor and blast protection, say engineers at the Jacobs School. They are developing a new material that could be used to make better body armor; prevent traumatic brain injury and blast-related lung injuries in soldiers; and protect buildings from impacts and blasts. It's the first time researchers are investigating the use of nanofoams for structural protection.

"We are developing nanofoams that help disperse the force of an impact over a wider area," said Yu Qiao, a structural engineering professor. "They will appear to be less rigid but will actually be more resistant than ordinary foams."

Researchers are in the first year of a three-year program funded by the Army Research Office. "We are getting some promising results," Qiao said.

The nanofoams are like honeycombs. They are porous and light – pores make up anywhere from 50 to 80 percent of the structure. Researchers have been trying to determine the optimal pore size to absorb energy from impacts. They have manufactured samples with pore sizes ranging from 10 nanometers to 10 microns. Preliminary results show that when pore size reaches tens of nanometers, the material seems to perform best. Those samples absorb energy from an impact or blast over a wider area, which makes the material more resistant to impacts and blasts. By contrast, in ordinary foams, energy is absorbed in one localized area, leading to quick failure. This problem, called damage localization, means that ordinary foams do not perform well as protection against impacts or blasts.

"People have been looking at preventing damage from impacts for more than a hundred years," said Qiao. "I hope this concept can provide a new solution."

Wearable Sensors Help Bioengineers Understand Infant Brain Development

Neonatal intensive care has brought amazing advances in the survival of critically ill newborns, particularly in the area of stabilizing babies with heart and lung problems. Now, experts are focused on continuous monitoring in order to treat brain injuries as they occur, to reduce the prevalence of cognitive and motor development issues that result from seizures, ischemia and brain hemorrhage. Currently, newborns in intensive care are wired up with electrodes designed to monitor vital signals such as heart rate, respiration and electrical rhythms of the brain. A new study of patients in neonatal intensive care at two San Diego hospitals led by bioengineering professor Todd Coleman and Dr. Mary J. Harbert is testing whether all of those bulky electronics that can damage or cause inflammation could be replaced with a stamp-sized wearable patch.

Comprised of tiny circuits, sensors, and wireless transmitters, the patch sticks to the skin like a temporary tattoo, stretching and flexing with the skin while maintaining high performance. By combining simultaneous, real-time measurements of multiple vital signs with Coleman's unique expertise in signal processing and quantitative neuroscience, the research promises to open up a new frontier in doctors' understanding of the developing newborn brain. For example, new insights into brain development such as the relationship between certain brain injuries and developmental disorders. Future sensors will be built with the help of UC San Diego's new e-beam writer (see more).

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