Focus on Research
Penn State Intercom......April 24, 2003

New flat motor can drive shape
shifters, movers and shakers

By Barbara Hale
Public Information

Penn State engineers have developed a low-cost, high-torque rotary motor, based on "smart" materials, that can be configured in a wide range of formats, including one as flat and thin as a CD case.

The inventors say that, in the flat format, the motor could be used to drive changes in the camber of airplane wings or fins, essentially shape-shifting the curvature o f the wing or fin surface. In other formats, the motor could work in tightly integrated spaces where other motors can't fit. For example, the "smart" material motor could serve as the drive element in thinner, lighter, laptop computers or other compact, portable consumer products or in manufacturing equipment that processes things by moving or shaking them.

Gary Koopmann, distinguished professor of mechanical engineering and director of Penn State's Center for Acoustics and Vibration (CAV), led the development team. He said the flat motor has a starting torque advantage over conventional electric motors since speed is not required for high torque output. The prototype flat motor has reached a free speed of 760 revolutions per minute and a maximum torque of 0.4 Nm. Components for the prototype cost less than $150 off-the-shelf. Koopmann estimates that an optimized version of the flat motor might cost as little as $10 to mass produce.

The device was patented recently by Penn State. The inventors are Koopmann; Chen Weicheng, CAV laboratory manager; George Lesieutre, professor of aerospace engineering and CAV associate director; Jeremy Frank, president, KCF Technologies; and Eric Mockensturm, assistant professor of mechanical engineering.

The new motor works by translating the bending of a "smart" material into the turning of a shaft. The "smart" material the inventors use is PZT (lead zirconate titanate), an inexpensive, commonly available piezoelectric that elongates when an electric field is applied to it. By bonding PZT to both sides of a tiny, flexible, metallic strip, they create an "arm" that can bend to the left and right in response to an electric field. Placing 12 of the "arms" star-fish-style around a central shaft, the inventors stimulate them simultaneously and they all bend in the same direction. A passive clamping system, either a ball and spring arrangement or a commercial one-way roller clutch, acts as a kind of turnstile that only allows the motion to ratchet along in one direction, translating the bending into rotation of the central shaft.

Koopmann explained that using passive clamping significantly improves the performance and lowers the cost of the flat motor versus inch-worm type designs, which also use the small oscillatory motions of smart materials but require precision machining.

The development of the new motor was supported by grants from the Defense Advanced Research Projects Agency.

Barbara Hale can be reached at bah@psu.edu.

$1 million NIH grant awarded
to conduct sleep apnea study
at Hershey Medical Center

Sleep apnea, a sleeping disorder that may affect as many as 18 million Americans, has emerged as a risk factor for high blood pressure, cardiovascular disease and premature death.

Urs Leuenberger, associate professor of cardiology, Penn State College of Medicine, and associate director of the Penn State General Clinical Research Center, was recently awarded a $1 million grant from the National Heart, Blood and Lung Institute ­ National Institutes of Health to conduct a study that may help to explain the connection between sleep apnea and heart disease.

"Some studies have already demonstrated a strong link between sleep-disordered breathing and hypertension and suggest that sleep-disordered breathing may cause high blood pressure, but the mechanisms are unknown," Leuenberger said. "We will look to the sympathetic nervous system, which controls blood vessel function, for answers."

Obstructive sleep apnea is a disorder in which a blockage in the throat or upper airway causes a sleeping person to temporarily stop breathing. Although millions of Americans have sleep apnea, only a fraction of them have been diagnosed by a physician.

A person with obstructive sleep apnea will experience multiple interruptions -- as many as 60 or more per hour -- in their breathing during the night, often caused by soft tissue temporarily collapsing and covering the wind pipe. This causes short periods of hypoxia or lower than normal oxygen in the blood.

"Our preliminary data showed that, when the blockage occurs, the sympathetic nervous system increases in activity and raises blood pressure in response to the drop in oxygen. At the same time, blood vessels aren't able to function normally," Leuenberger said. "In someone with obstructive sleep apnea, this can happen many, many times each night putting a lot of stress on the cardiovascular system."

The study aims to determine whether, after time, the increased stress on the cardiovascular system leads to a sustained increase in blood pressure.

In the study, which will be conducted in the National Institutes of Health-funded General Clinical Research Center at the medical center, a variety of measurements will be taken from 220 patients -- 110 with diagnosed sleep apnea and 110 without the condition. In some of these tests patients will put on a mask and breathe lower than normal amounts of oxygen to mimic the hypoxic state caused in patients with sleep apnea.

In addition to blood pressure measurements, some patients will undergo microneurography, which measures sympathetic nerve traffic -- the messages sent by the Central Nervous System and directed to the blood vessels.

Other patients will undergo microdialysis in which tiny probes are placed into the interstitial space -- spaces outside of cells -- in the leg to test the chemicals released by the muscle and the blood vessel response to the chemicals.

Doppler ultrasound will be used to measure blood flow in the arms and legs and patients' will be weighed because sleep apnea is more often seen in people who are obese.

"Together, this information will help us to shed light on the connection between sleep apnea and heart disease," Leuenberger said. "We hope that our findings might lead to a higher level of awareness among physicians and better treatment options for patients with obstructive sleep apnea."

Large-scale climate change linked
to fluctuations in Arctic mammals

By Barbara Kennedy
Eberly College of Science

Scientists have shown, for the first time, that changes in a large-scale climate system can synchronize population fluctuations in multiple mammal species across a continent-scale region.

The study compares long-term data on the climate system known as the North Atlantic Oscillation with long-term data from Greenland on the population dynamics of caribou and musk oxen (shown below).

"The Arctic can provide useful early-warning signals for the rest of the world because the species that live in this sensitive region are expected to be among the first to show the effects of the Earth's changing climate," said Eric Post, assistant professor of biology, who is a coauthor of the study along with Mads C. Forchhammer, associate professor of ecology at the University of Copenhagen in Denmark. "Here we have a very simple system with a very clear signal: two species on opposite sides of a continent that never mix, never compete for food and have no common predators, yet their population dynamics are synchronized. The only thing they have in common is the large-scale climate system that influences weather throughout the northern hemisphere."

Post and Forchhammer studied seven herds of caribou and six herds of musk oxen in Greenland, where the two species live on opposite coasts and are separated by an impassable continentwide ice sheet spanning about 600 miles at its minimum width. "We chose to study these two species in Greenland because their complete physical and ecological separation rules out the alter native explanations that have confounded previous studies of the role of climate in synchronizing population dynamics, leaving only weather as the controlling factor," Post said.

The large-scale system that affects winter weather in Greenland and much of the northern hemisphere is the North Atlantic Oscillation (NAO). "The North Atlantic Oscillation can be pictured as a fluctuating pressure corridor that squeezes and channels the westerly winds between North America and northern Europe, influencing the direction and speed of the winds and affecting temperature and precipitation on both sides of the North Atlantic Ocean," Post explained. "It also bears some relation to the much larger Arctic Oscillation, which is centered over the North Pole and which seems to exert its greatest influence on spring temperatures in the northern hemisphere."

In order to gauge how strongly the North Atlantic Oscillation affects local weather conditions on the coasts of Greenland, the researchers compared records of each herd's local weather history with the NAO index -- a measure of the condition of the North Atlantic Oscillation that has been in use from 1864 to the present. They then sequentially compared each of the caribou herds with each of the musk ox herds, looking at the degree of their geographical separation, the timing of their population fluctuations, the weather conditions affecting each herd and the degree of the NAO influence on the herd's population dynamics.

'We found that whenever the NAO had an approximately equal effect on the population dynamics of two herds, these fluctuations were more synchronized, even though the herds were on opposite sides of the subcontinent of Greenland," Post says. Similarly, the researchers found that whenever the North Atlantic Oscillation exerted opposite effects on herds of the two species, their population dynamics were out of phase with each other -- when one was thriving the other was declining.

RESEARCH
NEWS IN BRIEF

$1.25 million NIH award
funds study on feeding brain

Ian Simpson, professor of neuroscience and anatomy, recently was awarded a four-year, $1.25 million grant from the National Institutes of Health to study the blood-brain barrier, a system that regulates nourishment for the brain.

"The bottom line is understanding how the brain receives its fuel," Simpson said. "There are several diseases which are associated with impaired uptake of nutrients in the brain such as Alzheimer's disease. Other conditions such as stroke and diabetes also are closely related to the supply and demand of energy to the brain."

Simpson's goal is to investigate how the blood-brain barrier, which is made up of tightly coupled endothelial cells in the tiny blood vessels of the brain, serves as gatekeeper for the passage of nutrients intothe brain. These cells create a physical barrier, which can be "opened" only by interaction of the nutrients with specific transport proteins.

Two of the most important nutrients for brain health are glucose, which is the primary energy source for the brain, and iron, which is required for several different biochemical processes.

Both glucose and iron are essential for normal brain function and will be the focus of this investigation.

Scanlon receives
Investigator Award

Dennis P. Scanlon, assistant professor of health policy and administration, has received a three-year, $275,000 grant from the Robert Wood Johnson Foundation through its Investigator Awards in Health Policy Research program.

Investigator Awards are given annually to a select group of individuals whose crosscutting and innovative research shows the greatest promise of tackling the most challenging health-care and health policy issues facing America today.

Scanlon will use his award to assess whether relying on private sector purchasers of health care can lead to demonstrable improvements in quality as envisioned by the Institute of Medicine and others.

Specifically, he will conduct projects with private sector purchasing organizations such as the Leapfrog Group and the National Business Coalition on Health.

PENN STATE'S RESEARCH HERITAGE

At the Petroleum Refining Lab, chemists conducted the University's first major industry-sponsored research beginning in 1929. They improved the refining process of crude oil and pioneered in identifying its components. The lab was razed in 1958, but Penn State still ranks among America's top universities in industry-sponsored research.

Back