Monthly Archives: November 2012

Dissolvable Micro Mirrors Enhance Imaging, Administer Heat, Deliver and Monitor Drugs

Tufts University School of Engineering researchers have demonstrated silk-based implantable optics that offer significant improvement in tissue imaging while simultaneously enabling photo thermal therapy, administering drugs and monitoring drug delivery. The devices also lend themselves to a variety of other biomedical functions.

Microscopic image of a silk optical implant embedded with gold nano particles. When implanted in tissue and illuminated with green laser light, the particles converted light to heat, turning the reflector into a thermal therapy to control bacterial infection or kill malignant cells. Photo: Fiorenzo Omenetto

Biodegradable and biocompatible, these tiny mirror-like devices dissolve harmlessly at predetermined rates and require no surgery to remove them.

The technology is the brainchild of a research team led by Fiorenzo Omenetto, Frank C. Doble Professor of Engineering at Tufts. For several years, Omenetto; David L. Kaplan, Stern Family Professor of Biomedical Engineering and Biomedical Engineering chair, and their colleagues have been exploring ways to leverage silk’s optical capabilities with its capacity as a resilient, biofriendly material that can stabilize materials while maintaining their biochemical functionality.

The technology is described in the paper “Implantable Multifunctional Bioresorbable Optics,” published in the Proceedings of the National Academy of Sciences online Early Edition the week of November 12, 2012.

“This work showcases the potential of silk to bring together form and function. In this case an implantable optical form — the mirror — can go beyond imaging to serve multiple biomedical functions,” Omenetto says.

Video: silk optical implant embedded with gold nano particles

Dean Abriola and Collaborators Win Project of the Year

The Strategic Environmental Research and Development Program (SERDP) announced that Tufts engineers and collaborators are recipients of a 2012 SERDP Project-of-the-Year Award in the environmental restoration area for their project modeling groundwater contaminants on military installations. SERDP also announced five award winners in other categories.

Groundwater contamination from chlorinated solvents on military installations is a significant environmental liability for the Department of Defense. Many of the dense nonaqueous phase liquid (DNAPL) source zones developed decades ago as a result of historical practices and continue to contaminate groundwater today. In order to successfully treat this contamination, it is essential to understand the physical characteristics of the source zones.

Dean Linda M. Abriola, professor of civil and environmental engineering, and colleagues at Tufts School of Engineering–including Eric Miller, professor and chair of the Department of Electrical and Computer Engineering; Kurt Pennell, professor and chair of the Department of Civil and Environmental Engineering; and Associate Professor Andrew Ramsburg–collaborated with John A. Christ of the U.S. Air Force Academy to develop innovative tools that, for the first time, can provide key information about a source zone’s structure and characteristics, also referred to as architecture. This work, which combines high-end computational techniques and physical models, can help explain why contamination persists, how long it will persist, and what the best options are for treating it.

High-end computational techniques and physical models can help explain why contamination persists, how long it will persist, and what the best options are for treating it.

Whether a source will persist for decades or centuries is believed to be related to the ratio of ganglia to pools of contamination. DNAPL source zones often occur in tow different forms in the subsurface: as pools of contamination or as ganglia, thin web-like shapes that seep into the pores of the subsurface. Knowing the ration of ganglia to pools will help site managers decide on the most effective treatment to use for a particular contaminated area. The field tools developed by Dean Abriola and her team provide the means to determine the best treatment approach, thereby reducing the time and resources Department of Defense must spend to remediate this contamination. These tools also have immediate and wide applicability to the remediation of a large number of non-military sites that require mediation of subsurface DNAPL contamination.


Tooth Tattoo

Gold, silk and graphite may not be the first materials that come to mind when you think of cutting-edge technology. Put them together, though, and you’ve got the basic components of a new ultra-thin, flexible oral sensor that can measure bacteria levels in the mouth. The device, attached temporarily to a tooth, could one day help dentists fine-tune treatments for patients with chronic periodontitis, for example, or even provide a window on a patient’s overall health.

The sensor, dubbed a “tooth tattoo,” was developed by the Princeton nanoscientist Michael McAlpine and Tufts bioengineers Fiorenzo Omenetto, David Kaplan and Hu Tao. The team first published their research last spring in the journal Nature Communications.

The sensor (A), attached to a tooth (B) and activated by radio signals (C), binds with certain bacteria (D). Illustration: Manu Mannoor/Nature Communications

Before the tooth tattoos can undergo clinical testing, however, researchers will have to overcome some limitations. In order for the sensor to detect specific strains of bacteria, McAlpine says, his team will need to create new peptides or similar molecules that bond with only one particular strain. Constructing those won’t be easy. McAlpine notes that he’ll need to work with biologists to build them from the ground up, a process that could require the development of entirely new methods for assembling organic molecules in the lab.

The sensor’s physical size is also a consideration: the prototype is a bit too large for use in humans (the team tested it on a cow tooth), so making the whole package smaller will be another challenge. And, Kugel notes, thickness is a factor, too. It’ll be important to determine if patients will accept having a foreign object, no matter how thin, attached to their teeth.

“People are very sensitive,” Kugel says. “They can feel objects in the mouth that are 50 or 60 microns across”—about the thickness of a sheet of paper. “If it’s at all irritating to a patient, he or she will complain about it. You’d need to make sure it’s actually comfortable enough to leave in place for long periods of time.”

[David Levin is a freelance science writer based in Boston. This story was first published on TuftsNow, Nov. 1, 2012.]

Multitasking Overload and HCI Intervention

In an article on “The new workforce: Distracted and Drowning in Info“,  Steve Yoder writes:

“[T]here’s a growing body of research indicating that multi-tasking cuts into performance. Videogamers, who might be expected to have highly developed attention-switching skills, perform worse when multitasking than they do otherwise, according to a study in the July issue of the research journal Attention, Perception, & Psychophysics. And a study in the Proceedings of the National Academy of Sciences found that multitasking took a toll on the short-term memories of people between the ages of 60 and 80.”

Yoder references work conducted by Computer Science Professor Rob Jacob who has developed a wearable brain scanner that detects when workers are overwhelmed with multitasking and offloads some of the work to a computer. Jacob’s research in real-time measurement and machine learning classification of functional near infrared spectroscopy (fNIRS) brain data leads has allowed him to develop, use, and evaluate brain measurement as input to adaptable user interfaces for the larger population.



Breaking Point

They’ve got limited resources: a fixed amount of basswood, Elmer’s glue and an X-Acto knife. The goal: span an 18-inch gap with a bridge that holds as much weight as possible. That’s the plan at least, as teams of engineering students in Masoud Sanayei’s structural analysis course prepare for an annual competition, where they will learn real-life lessons.

“These are junior structural engineers with limited knowledge of applied mechanics and structural engineering in bridge design,” says Sanayei, a professor of civil and environmental engineering.

The teams put their designs to the test in a public contest of strength and skill, with bridges rated on aesthetics, load carried and efficiency (the ratio of bridge load to weight).

This year’s entries included colorful bridges that twisted, bent and snapped under loads ranging from less than 20 pounds to nearly 200 pounds. In a previous competition, one bridge withstood 376 pounds, still the record.

The “spaghetti” bridge from an earlier competition, a spectacular failure. Photo: Courtesy of Masoud Sanayei

The “spaghetti” bridge from an earlier competition, a spectacular failure. Photo: Courtesy of Masoud Sanayei

“They see there are so many ways for a structure to fail,” observes Sanayei. And it is failure that describes Sanayei’s most prized possession—a photograph of what he calls the “spaghetti” bridge—a warped and buckled span that was terribly designed and thus collapsed spectacularly during one competition.

“Understanding structural failures is crucial to the learning process,” says Sanayei, who requires the students to write a detailed analysis of where and why their bridges failed—and how they would go about preventing such failures.

“This is a real learning experience for structural engineers who, in the future, are going to design our highway bridges for safety, efficiency and durability,” says Sanayei.