Researchers at MIT have unexpectedly found a way to 3D print active electronics, that is, transistors and components that control electrical signals, without using semiconductors or even special manufacturing technology.
This goes far beyond what we can currently do with 3D printers. If this method is perfected, it could eventually usher in a new wave of prototyping, experimentation, and even DIY projects for do-it-yourselfers.
With 3D printing, any combination of materials, including thermoplastic filaments, resins, ceramics and metals, are layered in successive thin layers to form a 3D object. This means you can print all kinds of things, from action figures to jewelry, furniture, and buildings.
So why not 3D print electronics? The main challenge is that semiconductors, which are traditionally made from pure silicon and cut into thin wafers to be made into tool chips, are very brittle. Its functionality can be affected by dust, airborne particles and microbes, and even temperature and humidity. They are also carefully handled in clean rooms, where air quality and other factors are carefully controlled to ensure that the chips manufactured inside them function accurately.
Additionally, modern chip design is extremely complex, with millions or billions of transistors packed into tiny processors using nanometer-scale processing techniques. This is much more precise than we can currently achieve with standard 3D printers.
For reference, the IBM Gekko chip that powered the Nintendo GameCube in 2001 had 21 million transistors. The Apple A12 Bionic chip in the 2018 iPhone XS contains 6.9 billion transistors and is manufactured using 7nm process technology.
To be clear, 3D printing modern devices is not at all what the MIT researchers were looking for. In fact, they didn't even have semiconductors in mind when they discovered it.
The researchers were making magnetic coils using a process called extrusion printing for another project. It was then that they realized that the material they were using (a polymer strand impregnated with copper nanoparticles) exhibited a significant increase in resistance when an electric current was passed through it. Once the current was stopped, the resistance of the material dropped to normal.
This is the property we see in semiconductors like silicon. That's why we use it to make transistors that turn on and off to form logic gates in processors.
“We saw that this was something that could help take 3D printing devices to the next level,” said Luis Fernando Velásquez García, senior research scientist at MIT's Microsystems Technology Laboratories. “It offers a clear way to provide a certain degree of 'intelligence' to an electronic device.”
Luis Fernando Velásquez García
The team demonstrated fully printed resettable diodes and transistors using this inexpensive material. These are simple, yet essential components of electronic devices that typically use semiconductors that are difficult to work with.
These transistors are a few hundred microns in size, which is not as small or as powerful as what you would find in an iPhone processor. However, they are durable and can be used for a variety of simple applications. It's about something as simple as a motor switch, turning it into parts for integrated circuits.
“The truth is that there are many engineering situations that do not require the best chips,” said Fernando Velásquez-García. Ultimately, all you care about is whether your device can do the job or not. This technology is capable of addressing such limitation.
By using a biodegradable material and not requiring clean rooms, this method can be used to make simple electronics in places where advanced manufacturing is difficult, such as remote and “onboard spacecraft” research laboratories.
That's what I call a happy accident. The research article has been published in the journal Virtual and Physical Models.
Source: MIT News
