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:
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.
