Researchers at MIT have unexpectedly found a way to make transistors and other electronics components without using semiconductors.
The main problem with 3D printing electronics is that semiconductor elements consist of thin layers of silicon and are extremely fragile. Their functionality can be affected by dust, temperature, and humidity. Therefore, the chips are created in clean rooms where all factors are strictly controlled to ensure that the chips work accurately.
Modern chip design is extremely complex: they consist of billions of transistors and are manufactured using nanometer-scale technology. This process is much more precise than the capabilities of modern 3D printers allow.
The MIT scientists didn’t actually try to reproduce modern chips or even think about something like this — the opportunity arose almost by accident. Earlier this year, they made magnetic inductor coils using a process called extrusion printing — where a printer melts filament and sprays the material through a nozzle, making the object layer by layer.
The researchers noticed that the material they were using, a polymer filament doped with copper nanoparticles, exhibited a large spike in resistance when they passed a large current through it. As soon as the current was turned off, the resistance returned to its normal value. The property of changing resistance under the influence of current allows the creation of transistors.
«We saw that this is something that can help take 3D printing equipment to the next level. This method offers a clear way to provide a certain degree of «intelligence» to an electronic device», — says Luis Fernando Velazquez-Garcia, principal scientist at MIT’s Microsystems Technology Laboratory.
The team demonstrated fully 3D printed reusable fuses and transistors using this inexpensive material. Measuring a few hundred microns, these transistors are not as small and efficient as those in a modern processor. However, they are durable and can be used for simple tasks.
«The reality is that there are many engineering situations that don’t require the best chips. At the end of the day, all you care about is whether your device can perform the task. This technology is capable of meeting some of the» constraints,” Velázquez-García says.
Thanks to its biodegradable material and the lack of need for clean rooms, this method of manufacturing simple electronics can be used in places where it is difficult to produce high-quality devices, such as remote research laboratories, even on board spacecraft. Research published in the journal Virtual and Physical Prototyping.
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