WHY THIS MATTERS IN BRIEF
As we store more sensitive information in a wider array of devices we need ways to protect it and electronics that dissolve are one way.
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Neurons are remarkable. Simply by firing in certain patterns and at particular frequencies in concert with one another, they endow us with something incredibly valuable – memory. So it’s no wonder that scientists have long sought to mimic neural networks, which are both compact and efficient, with electronic devices.
One way is with the development of memristors, devices that retain a “memory” of the direction and amount of electrical charge that has flowed through them. Over the past decade, researchers have made some progress in developing memristors, but the latest advance comes with a twist – this new memristor can dissolve in water.
It’s part of a growing trend to create what I call Transient Electronics, that is electronic systems that perform their tasks and then dissolve into nothing. And if you ask who might be interested in such a technology, well it has applications in not only defence, where you want your drones, for example, to vaporise if they’re captured, like this so called Vampire Drone that turns to gas at sunrise from DARPA, the US military’s bleeding edge research arm, as well as healthcare applications, where we don’t necessarily want electronic “stuff” hanging around in your body forever – such as these bio-electronic implants that heal damaged nerves, which I talked about recently.
While the new memristor design could also result in more environmentally friendly electronic devices, it is, for now, perhaps most useful for those who want to stop valuable information from falling into the hands of an enemy.
“Combining transient materials that can physically disappear on demand within a memristor device can be an effective way to achieve secure storage applications,” explains Hong Wang, a researcher at the School of Advanced Materials and Nanotechnology, at Xidian University in China, adding, “For example, it can be more convenient for us to throw a transient storage device in water when information security is under serious threat. This [holds] great value for military applications, especially.”
Wang’s team recently published a description of their design for a soluble memristor in IEEE Electron Device Letters. Using a water-assisted transfer printing method, they were able to transfer layers of silver and magnesium oxide, in combination with tungsten-based electrodes, onto transient substrates. They arranged these components so that the end result is a memristor that mimics the signalling between neurons.
Just as a threshold amount of calcium ions dictates how many signalling molecules neurons are released to their neighbours, a threshold amount of voltage can be used to control the flow of silver ions through the memristor.
But with neurons, the frequency at which they fire is key to creating a strong neural network. Neurons that fire in rapid succession are more likely to form stronger connections with one another. This phenomenon is captured by the common saying, “Neurons that fire together, wire together.” This same effect can be seen in the silver–magnesium oxide memristor, applying voltage more frequently strengthens the conductance of the device.
This system closely mimics the short-term plasticity of our own neural system, Wang notes.
“It proves that such a transient synaptic device can emulate short-term neural activity effectively, which paves the way to create secure neuromorphic computing applications.”
This new design will need a bit more work though before it’s commercialised, but it does demonstrate a desirable method for stopping information from falling into enemy hands. Simply throw it into some deionized water and the key components will dissolve within 30 minutes.
