As the price of microcontrollers plummeted, so did the appearance of more. Today you will find microcontrollers in your car, your household appliances and even children’s toys. But you don’t often see them embedded in things that are either too cheap or too flexible, like a bandage. Part of the reason is the price of silicone chips and part of the reason is that silicone chips do not appreciate flexibility. What if you could make a CPU out of flexible plastic for less than a penny? What application should that open? Pragmatic – an organization working to make this possible – thinks it will open up a whole new world of smart items that is unimaginable today. They worked with a team from the University of Illinois at Urbana-Champaign to create a prototype plastic CPU with impressive results.
It’s still a matter of research and dreams, but a team of researchers has worked to create 4-bit and 8-bit processors using IGZO-indium gallium zinc oxide-semiconductor technology. This technology can be placed on plastic and will work even if you bend it around a radius as small as a few millimeters.
The main problem seems to be the yield. When the ARM 32-bit M0 CPU was placed on plastic, the yield was poor due to the high number of gates. These new processors are simplified 4-bit devices that account for 81% of the yield. As a result, it can cost less than a penny to manufacture the devices.
The final design fits in at 5.6 square millimeters of die and has about 2,100 devices – comparable to an Intel 4004. In contrast, the M0 has more than 56,000 devices. 8-bit plastic CPUs also worked but had a similarly low yield. What do you do with a flexible CPU that costs a penny or two? Does it require more than a typical 4-bit processor?
Of course, the University of Illinois Urbana-Champaign is home to a very famous fictional computer and some non-fictional computers. However, although the M0 was placed on plastic, it was not without significant compromises.