Flexible electronics (flex circuits) is science fiction becoming reality. Traditionally, just electrical components attached to a flexible substrate, and not quite the paper thin electronic newspaper many dream of. Recent research is attempting to push towards that concept and make the circuitry flex with the substrate. The main issue that has held back progress in this area comes from how the integrated components effect each other as the substrate bends. As the circuit flexes the components get close to each other and cause electromagnetic interference, short circuit, and generally degrade the overall device.
University of Tokyo's PEN Flash (via University of Tokyo)
Back in 2009, a research team from the University of Tokyo (UT) made flexible organic flash memory in a polyethylene naphthalate (PEN) resin substrate. Geared towards e-paper devices or large-area sensors, the non-volatile memory could be curved until it reached a radius of 6mm before the onboard transistors started to interfere with each other's operation. The group, led by Takeo Someya and Tsuyoshi Sekitani stated that they would attempt to fix this issue by adjusting the layers. No new developments have come from the school.
KAIST Flexible RRAM around a 1cm quartz rod (left) and the memory layer cross section (right) (Via KAIST)
However, the Korea Advanced Institute of Science and Technology (KAIST) has just overcome past issues with flexible memory by simply adding a newer technology into the mix, memristors. The research team, led by Professor Keon Lee of the Department of Materials Science and Engineering at KAIST, overcame all issues by placing single-crystal silicon transistors alongside the memristor elements, which are unaffected by "cell-to-cell" interference. The result, KAIST's flexible non-volatile resistive random-access memory (RRAM).
Professor Lee commented on the achievement, "This result represents an exciting technology with the strong potential to realize all flexible electronic systems for the development of a freely bendable and attachable computer in the near future."
The memristor, conceived by Leon Chua in 1971, was first commercially produced at HP Labs in 2008 and is being considered as a replacement for Flash, SSD, SRAM, and DRAM within the next few years. The KAIST team has demonstrated that their RRAM flexible memory can write/read/erase perfectly and could bring the budding technology into whole new markets. Consider memory embedded into clothes or shoes, a necessary component for the much lauded flexible display and batteries on the way.
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What is the symbol for a memristor?
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