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EETE OCTOBER 2012

NEWS & TECHNOLOGY FLEXIBLE ELECTRONICS Ultra-thin, flexible chip features bendable and stretchable interconnects By Julien Happich Imec announced it has integrated an ultra-thin, flexible chip field are welcomed to join the R&D program. with bendable and stretchable interconnects into a package For the demonstration, the researchers thinned a com- that adapts dynamically to curving and bending surfaces. mercially available microcontroller down to 30µm, preserving The resulting circuitry can be embedded in medical and life- the electrical performance and functionality. This die was then style applications where user comfort and embedded in a slim polyimide package unobtrusiveness is key, such as wearable (40-50µm thick). Next, this ultrathin chip health monitors or smart clothing. Today, was integrated with stretchable electrical most electronic appliances are rigid, or wiring. These were realized by pattern- at most mechanically flexible. A growing ing polyimide-supported meandering number of applications, however, require horseshoe-shaped wires, a technology electronics that dynamically adapt to developed and optimized at the lab. curving and bending surfaces. Some ex- Last, the package is embedded in an amples include biomedical systems such elastomeric substrate, e.g. polydimeth- as unobtrusive, wearable health monitors ylsiloxane (PDMS). In this substrate, the (e.g. electrocardiogram or temperature conductors behave as two dimensional sensors), advanced surgical tools, or con- springs, enabling greater flexibility while sumer electronics such as mobile phones embedded in smart preserving conductivity. textiles. Imec’s associated lab at the University of Ghent has This research is supported by the Agency for Innovation by pioneered this technology, moving it toward industrial applica- Science and Technology in Flanders (IWT) through the SBO- bility. Industrial partners that want to build a critical lead in this BrainSTAR project. GaAs nanowires on graphene for new flexible optoelectronic devices By Nick Flaherty RESEARCHERS IN NORWAY are commercializing a new mobile phones,” he said. “Our invention fits perfectly with the technique to grow vertical GaAs nanowires on graphene for production machinery they already have. We make it easy for new flexible optoelectronic devices. The hybrid material offers them to upgrade consumer electronics to a level where design excellent optoelectronic properties, says Professor Helge We- has no limits.” man, a professor in the Department of One possible device with very Electronics and Telecommunications large market potential is a nanowire at the Norwegian University of Sci- solar cell. This type of solar cell has ence and technology in Trondheim. the potential to be efficient, cheap He is also CTO and co-founder of and flexible at the same time. The the company created to commercial- invention also makes it possible to ize the research, CrayoNano. “We imagine a future with self-powered have managed to combine low cost, nanomachines and advanced 3D inte- transparency and flexibility in our new grated circuits built on graphene and electrode,” he said. semiconductor nanowires, enabling The technique uses atomically thin smaller and more efficient electronics. graphene and Molecular Beam Epi- Weman sees flexible self-powered taxy to grow vertical nanowires. “We do not see this as a new consumer electronics integrated into everything from clothes to product,” said Weman. “This is a template for a new production notepads, and of course traditional cell phones, tablets and ex- method for semiconductor devices. We expect solar cells and ercise accessories. “Semiconductors grown on graphene could light emitting diodes to be first in line when future applications become the basis for new types of device systems, and could are planned.” transform the semiconductor industry by introducing graphene “Companies like IBM and Samsung are driving this develop- as a preferred substrate for many applications,” he said. The ment in the search for a replacement for silicon in electronics as technology has been patented by NTNU Technology Transfer, of well as for new applications, such as flexible touch screens for which CrayoNano is a spin-off company. 8 Electronic Engineering Times Europe October 2012 www.electronics-eetimes.com


EETE OCTOBER 2012
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