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Electric Fields Assemble Devices

The easiest way to assemble a device is to provide an environment that causes it to self-assemble. As components continue to shrink, this could become the only practical means of assembly.

In contrast, today's electronic devices are generally put together using tiny equivalents of assembly line robots that pick up and place components on chips. This approach can be scaled down only so far because at a certain point natural forces cause components to stick to assembly mechanisms.

Researchers from the National Microelectronics Research Centre (NMRC) in Ireland have sidestepped the problem by using electric fields to direct assembly. They have used the technique to assemble arrays of gallium arsenide light-emitting diodes onto silicon chips.

The method, dubbed Field Controllable Assembly, is compatible with contemporary optoelectronics manufacturing methods, and could lead to low-cost, rapid assembly of optical and electronic devices.

The researchers' self-assembly device contains an array of electrodes on a silicon surface that allows them to put electric fields of specific configurations on the surface of the chip. The fields attract electric charge at a particular spot and repel it everywhere else, allowing for rapid movement and assembly of components.

A key factor of the researchers' self-assembly technique is that the objects involved are not required to recognize the parts they must connect to.

The researchers' tests used components the width of a human hair, but could be used to assemble components several orders of magnitude smaller, according to the researchers.

The method could be used practically in two to five years, according to the researchers. The work appeared in the May, 2004 issue of Nano Letters.

--Technology Research News