Nanosprings Could Lead to Biomedical Sensing Applications

Originally Published MDDI December 2003

R&D DIGEST

Eric Swain

A new zinc oxide nanostructure could end up forming the basis for parts of medical microsystem applications. 

Researchers at the Georgia Institute of Technology (Atlanta) have developed a technology called nanosprings. Helical shapes are formed from long single crystals of zinc oxide. Significantly, they have piezoelectric and electrostatic polarization properties that could be of use in small-scale sensing and microsystem applications, perhaps in the medical field.

Nanosprings are similar to “nanobelts,” first reported in 2001, but are smaller. They are up to several millimeters long but are 10–60 nm wide and 5–20 nm thick. 

“These structures . . . are a major step toward a new system of nanostructures,” says Zhong L. Wang, director of Georgia Tech's Center for Nanoscience and Nanotechnology and a professor at its School of Materials Science and Engineering. “Piezoelectric and polar-surface-dominated smart materials based on zinc oxide are important because they could be the transducers and actuators for future generations of nanoscale devices.”

Specifically, he says, “they could be used to measure pressure in biofluid or in other biomedical sensing applications. You could use them to measure nano- or piconewton forces. In micromechanical systems, these structures could provide the coupling between an electrical signal and a mechanical motion.” In addition, fluid flows, airflows, strain forces, and acoustical waves that were previously imperceptible might now be detected.

Also, the structures appear to have a strong electrical charge because of electrostatic polarization. That means they might attract specific molecules, which would make them useful as biosensors to detect single molecules or cells. Thus they might be a fit for in-body biomonitoring applications.

“We would like to use these materials for in situ, real-time, nondestructive monitoring within the body with high levels of sensitivity,” says Wang, who has been collaborating on the research with Xiang Yang Kong. 

It will be a while before applications are found, however. “We can cut this material into specific lengths and manipulate it, but that's only the first step,” Wang says. “We need to know how to integrate this into existing technology. We can generate voltages, but how can we measure them? We must learn to calibrate a system, and quantify the data to know what force is being applied.”

Support for the research came from the National Science Foundation, the NASA Vehicle Systems Program, and the Department of Defense Research and Engineering program.

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