Plotting chemicals

Team member Seunghun Hong gets to grips with writing on the nanoscale

Researchers at Northwestern University have built a device that can draw patterns of tiny lines just 30 molecules thick and a single molecule high. The device known as an eight-pen nanoplotter produces eight identical patterns at once and extends the team's previous dip-pen nanolithography towards mass producing nanoscale devices and circuits by converting what was a serial process to a parallel one.

The method, which is analogous to using a quill pen but on a billionth the scale, could soon be made competitive with optical and stamping lithographic methods used for patterning large areas on metal and semiconductor substrates, including silicon chips.

With the eight-pen nanoplotter, only one of the read-write heads - the primary nanopen, is actively controlled by computer, the other seven writing tips are passive and follow the lead of the pen with the imaging tip, drawing identical patterns a fixed distance apart. "Our multiple-pen, parallel process nanoplotter gives the nanotechnologist a powerful new tool", explains chemist and team leader Chad Mirkin. "The miniaturisation of the plotter writing technique opens up exciting avenues of doing things differently, better and on a much smaller scale than they are today", he says.

Mirkin and colleague Seunghun Hong suggest that the technology could support hundreds even a thousand nanopens working in parallel to miniaturise electronic circuits and even produce patterned arrays of DNA for biological assays and genomics. It could also be used to place thousands of different medical sensors on an area much tinier than the head of a pin.

Mirkin hopes to have a working 50-pen nanoplotter by the end of 2001.

Reference:
C. A. Mirkin and S. Hong, Science, 2000, 288, 1808.^*

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