Thursday, March 01, 2007

From the Labs: Nanotechnology

Continued from page 1

By Kevin Bullis

Practical Nanosensors
An easier way to make nanowire sensors and integrate them into electronics could lead to handheld detectors of pathogens, cancer

Source: "Label-Free Immunodetection with CMOS-Compatible Semiconducting Nanowires"
Eric Stern et al.
Nature 445: 519-522

Results: Researchers at Yale University have found an easier way to manu­facture nanowire sensors, and their process is compatible with those used to make computer chips. The sensors can detect small concentrations of proteins about as reliably as previous nanowire sensors could.

Why it matters: Today, detecting biological molecules in ultrasmall concentrations requires tagging them with fluorescent dyes and viewing them through bulky optical readers. Nanowire sensors generate electronic signals rather than optical ones, and they do not require tagging, so they can be much smaller and easier to use. As a result, they could lead to handheld sensors that can screen for faint traces of hundreds of pathogens or for early signs of cancer. The new technique could also make it much easier to integrate nanosensors and the electronics that process their signals on individual chips. Such sensors would be more practical to mass-produce.

Methods: The researchers first created patterns on silicon using conventional lithography; chemical etching then removed the nonpatterned silicon, leaving behind silicon wires. But because the wires were still too thick, the researchers let the etching agent continue to eat away at the material under the edges of the pattern.

Next Steps: The researchers are demonstrating the sensors' ability to detect different molecules, such as virus particles, DNA, and a wider range of proteins.