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Researchers Are Bending Memory for IoT Products

A photograph of the phase-change memory test vehicle bent around an 8mm aluminum rod.
A photograph of the phase-change memory test vehicle bent around an 8mm aluminum rod. (Image credit: Stanford University)

We're far past the point where personal computers are the only things we own processing data. Not only have we moved on to more portable devices, like smartphones, but we're also seeing everyday items, like mirrors, wristbands and even smart bandages and have need to compute. As we continue putting more chips into more things, there's need for flexibility -- literally. A research team at Stanford University addressed that this week with research around bendable memory that can serve as storage for flexible electronics. 

The report shared in Science enables the manufacturing of memory devices in a flexible substrate. The manufactured test device was also able to be wrapped around a metal pin with an 8mm diameter and still work. There was no decrease in performance even after 200 bending and straightening cycles, and stored information was readable up to 1,000 times before any sort of deterioration was seen.

In an attempt to develop storage options in a flexible medium, the researchers explored phase-change memory (PCM). Adding flexibility to electronics has been mostly pursued through the usage of plastic-based components (polymers), as they possess the characteristics required not to crack under pressure. The researchers discovered that plastic may actually be one of the most important enablers for PCM research in general because plastic can serve as an insulator, meaning it doesn't conduct heat or electrical currents well.

PCM makes use of components that change their atomic organization when they reach certain thermal thresholds. As the researchers explained: 

"Phase change materials leverage changes in structure into differences in electrical resistance that are attractive for computer memory and processing applications." As such, they created a PCM device that is flexible by using "layers of antimony telluride and germanium telluride deposited directly on a flexible polyimide substrate. The device shows multilevel operation with a low switching current density. The combination of phase change and mechanical properties is attractive for the large number of emerging applications for flexible electronics."

To know the stored value (or values, since phase-change has enough different conductivity levels to enable multi-bit information to be derived from them), one needs only send a tiny amount of electricity through it and calculate the resistance. PCM is nothing more than memory storage banks made of phase-change materials that display this state versatility. 

One benefit of this is that states are typically coherent: they don't change by themselves. That makes this a persistent memory system, meaning that a constant flux of energy isn't required for the information to be retrievable, which is important in an energy efficiency perspective. 

The issue with typical phase-change materials, however, is that energy must be driven through them in order to generate enough heat to initiate a phase change, and that drives efficiency down. 

This is where plastic may prove to be revolutionary. The Stanford researchers discovered that not only did plastic make the memory semiconductor flexible enough to be bendable, it also lowered the energy requirements for writing information to memory. The embedded plastic insulates the phase-change material, slowing down the energy loss that would otherwise occur if heat was propagating beyond the area of the phase-change material. The researchers quote their PCM design's power requirements as being 100 times lower than current ones fabricated on a silicon substrate. 

Ultimately, this research furthers the development of flexible tags that could be applied to extremely low-power materials that require flexibility from its electronics. New tech often starts off in the enterprise space, and possible applications for this research include biomonitors that can be attached to your internal organs and wearable electronics patches that can display information directly on your skin. 

The research could also help revolutionize phase-change-based computing, which is already preferred in neural network training, for example. Paired with the recent development and proof of concept production in the Plastic Arm project, which developed a flexible Arm processor built out of, you guessed it, plastic, it's only a matter of time until we more see bendable tech in our lives.