The soul of a new chip

Living systems can be used to produce microscopically small components of uniform size that potentially can be used to build electronic devices, according to researchers at The University of Texas at Austin.

By combining proteins from viruses with inorganic elements commonly used as semiconductors, a UT Austin research team has produced hybrid materials called electronic biocomposite materials. Biocomposite materials exist in nature in the form of such substances as shell and bone.

By extending the processes that result in naturally occurring biocomposites to substances commonly used in construction of electronic components, the scientists said they are paving the way for development of a host of technological marvels — potential building blocks for transistors, wires, connectors, sensors and computer chips far smaller than anything manufactured so far.

‘Nature has amazing control over forming materials like shells and bones, but never ‘moved on’ to electronically important materials like semiconductors,’ said Dr. Angela M. Belcher, of UT Austin’s department of chemistry and biochemistry and the UT Austin Texas Materials Institute. Belcher explained that ‘in my group, we focus where nature left off. We are learning from nature, learning how nature makes materials and applying this to other systems.’

Belcher and her graduate student, Sandra Whaley have been isolating viruses containing proteins that can combine with gallium arsenide, silicon, indium phosphides and zinc selenide. Belcher and her students have identified proteins at the ends of viruses that can tell the difference between similar semiconductor alloys and bind to the ones the scientists prefer.

‘We are the only group using this approach,’ said Belcher, a materials chemist with expertise in the fields of biomaterials, biomolecular materials, organic-inorganic connections and solid-state chemistry.

When the living proteins bind to the inorganic particles chosen by the scientists, the particles eventually will be ‘assembled’ by the proteins into desired patterns. In effect, the living organisms ‘grow’ uniform components so tiny scientists must use atomic force and electron microscopes to see them.

Belcher says a rough comparison could be made to a car putting itself together on an assembly line, although she said the assembly line process is primitive in comparison with the precision that the viruses can achieve. ‘A lot of organisms can make materials better than we can manufacture them,’ she said.

Belcher says any commercialisation of products resulting from her research would be some years away. The next research step will be working with the materials to try to integrate them into electronic devices.

The new field of biocomposites appears to overturn some of the basic concepts most people have about a natural world divided among animals, vegetables and minerals. Actually, the dividing lines between what is considered biological and what is considered mineral always have been fuzzier than is commonly assumed.

‘Biocomposite materials have been in existence for millions of years. We, ourselves, are biocomposite materials,’ said Belcher.

Belcher said her researchers went through 100 million viruses before slowly determining which ones worked best with certain materials. She said various virus and semiconductor combinations were tried. Only proteins that bound themselves tightly to the semiconductor survived the experiment and were cloned.

Belcher’s work cuts across the fields of inorganic chemistry, materials chemistry, molecular biology and electrical engineering. ‘We are a multi-disciplinary lab. We do it all,’ she said. ‘This project would not have worked without the ability to use all three approaches. I would not have been able to come up with this idea had I not studied in all these fields.’

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