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Printed Electronics World
Posted on January 23, 2009 by  & 

Self-healing electronics

Traditional electronics sometimes has inbuilt redundancy to tolerate damage. NASA is interested in printed electronics because, being relatively large area, it can better tolerate damage by particles in space when the silicon chip is usually destroyed.
There is now an interest in self-healing electronics, with wireless sensor networks and the internet self healing by the mesh networking nature of the system rather than the design of the hardware. However, self healing devices are also of interest.
Of course we are a long way from mimicking the sea creatures that reform even when broken down to powder and dispersed in the water but IDTechEx has reported a French invention of a self healing elastic polymer. Break it and hold the two pieces together and they rejoin, forming one elastic polymer again even at room temperature.
In a completely different approach, it has been found that certain nanoparticles can be dispersed through a material and migrate to cracks so efficiently that self-healing composites, that repair themselves when damaged, can be envisaged.
Researchers at the University of Pittsburgh and University of Massachusetts have already experimented with composites made up of transparent plastic loaded with spherical particles only about five nanometers or billionths of a meter wide underneath brittle silicon oxide. At high temperatures, cracks form in the brittle silicon oxide because it and the plastic bonded to it expand at different rates in response to heat.
With the right coating, which in this case was an organic compound known as PEO, the nanoparticles automatically migrate toward cracks in the silicon oxide. This is essentially because the molecules the plastic is made of are about the same size as the nanoparticles, making it hard to mix them. When a crack forms, the plastic has a chance to force the particles out - the nanoparticles burrow past the molecular chains making up the plastic like meatballs slipping through spaghetti, with the chains rebounding after the particles move past to leave the plastic intact. This ability to migrate toward and cluster around the cracks depends very much on the size of the nanoparticles.
While the researchers have demonstrated composites where embedded nanoparticles migrate to and cluster around cracks, they still have to develop a material where such nanoparticles can then seal the crack.

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Posted on: January 23, 2009

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