Can flexible chips track your girlfriend's mood? Spoiler: coming soon

The topic of flexible chips began to be accelerated back in the 2010s, but this development still raises more questions than answers. We decided to figure out who was at the origins and when, how technologies changed, and whether flexible chips can really be used to monitor everything: from the shelf life of a product to the state of human health.

How it all began

Traditional chips for electronic devices are produced on silicon substrates. But silicon is a rigid material, so such substrates cannot be bent. At the same time, both a supercomputer and wireless headphones need a processor. And while a hard chip can easily fit into a server, developers have a more difficult time with small devices like headphones or smart watches. Then scientists thought that the chips could be made flexible. Here's how the work progressed.

2011

The thickness of the thinnest experimental silicon chips at this time is 2 nm. The École Polytechnique Federale de Lausanne has created a computer chip made from molybdenite. The thickness of one layer of this material is only 3 atoms, which means that chips can be made three times thinner than the thinnest silicon ones. The material picks up electrical signals better than silicon. That is why scientists have suggested that molybdenite transistors will have higher energy efficiency, and this opens up prospects for the production of more complex chips.

Another advantage of molybdenite is its flexibility, so it can be used to create flexible chips. It seemed that one day, based on such chips, they would make a computer that could be twisted, or elastic devices that could be attached to the skin, and they would follow the curves of the human body.

Swiss scientists worked on molybdenite chips for another eight years, but since 2019 there is no news about developments.

Also in 2011, Belgian scientists presented the world's first processor based on organic semiconductors at the ISSCC exhibition. The chip had 4000 transistors and 8-bit logic. The processor was similar in power to a silicon chip from the 70s, but it had an important advantage: it was bendable. It was assumed that the chip could be used in displays and other devices – for example, to find out whether products are suitable for consumption. In addition, scientists stated that flexible chips are about 10 times cheaper than silicon chips and that it is only necessary to establish mass production of raw materials for their manufacture. No one, of course, fixed anything.

2017

In Austria they created a primitive microprocessor based on the same molybdenite. The microprocessor had 115 transistors, and in size it turned out to be hundreds of times larger than those installed in Intel and ARM processors of that time.

The developers were confident that increasing the performance of the chip would not be difficult. They believed that their version of a flexible microprocessor would be easier to use in wearable devices and touch screens. If a smartphone with such a display falls, it will not break, but simply bend. But in Austria, the topic of flexible molybdenite chips did not come up either – there is no news about fresh developments.

2021

If nothing has been heard about the developments of Swiss, Belgian and Austrian researchers for a long time, then the “British scientists” from ARM tried their best. They first released their flexible chip prototype in 2015. But, according to the developers, then the general level of technology development prevented them from creating a full-fledged experimental model. Only in 2021 they introduced a new flexible chip – a functional processor PlasticARM.

Instead of silicon and molybdenite, the developers used polyamide for the substrate, and the transistors were made using TFT technology – thin-film metal-oxide. The almost 60 mm2 chip is a 32-bit version of the Cortex-M0 microcontroller from ARM, which is equipped with 128 bytes of RAM and 456 bytes of ROM. According to the developers, the new chip is at least 12 times more complex than any of its predecessors.

The processor operates at frequencies up to 29 kHz, and consumes no more than 21 mW of energy – and this is a significant achievement for flexible chips. Although, if you compare PlasticARM with the “inflexible” ARM Cortex-M0+ processor, the comparison will not be in favor of the first. ARM Cortex-M0+ at frequencies up to 1 MHz consumes almost half as much.

After a series of tests, ARM developers stated that the chip completed all test programs and is fully functional. In their opinion, even with low productivity, a flexible chip can be used in everyday situations – for example, to control the quality of milk, alcohol and perfumes, and used in the production of clothing and wearable patches. And perhaps this is also due to the low cost of production. True, the developers have not yet said how much such a chip could cost.

Latest Developments

Flexible chips and devices with them have not yet entered mass production, so scientists and engineers continue to work in this direction.

September 25, 2024 British chip manufacturer Pragmatic Semiconductor introduced A 32-bit microprocessor that is fully functional even when twisted.

Flex-RV runs on the open RISC-V instruction set. Thin-film transistors made of indium gallium zinc oxide (IGZO) are placed on a flexible polyamide substrate and supplemented with machine learning functions. The developers believe that they have created an ultra-low-cost version of the microprocessor that will be compatible with many devices.

To produce a flexible chip, a polyamide substrate with a thickness of 0.6 microns was used. The test sample has a matrix size of 9 × 6 mm and 20 contacts. The core area of ​​each microprocessor is 17.5 mm2, and the number of elements is 12,596. The processor power consumption is 5.8 MW at 3 V. The Flex-RV architecture allows for connection of external devices, such as a display.

Unlike Flex-RV, all previous versions of flex chips were non-programmable. And the Pragmatic Semiconductor processor can run arbitrary programs written in high-level languages, such as C. The ISA can also be extended with new instructions, while the processor remains RISC-V compatible.

The chips were tested at rest and then under mechanical loads. In the first case, the average clock frequency was 52 kHz, and the maximum was 60.

To test the functionality of the chip under mechanical stress, it was wound around a smooth cylinder until the chip bent to the radius of curvature of the cylinder. The processor was tested on 3-, 4- and 5-mm parts. The experiment showed that the chip works correctly with a bending radius of 3 mm, while losing only 2.3–4.3% in performance. Clock speed indicators changed slightly.

Pragmatic Semiconductor believes that the new flexible chip will be in demand in common consumer products:

• intelligent packaging and labels – to track the quality of contents and simplify the search for items in warehouses;

• smart patches — in order to administer subcutaneous medicine in a timely manner to people who constantly need such procedures;

• disposable medical implants and test strips – to monitor the body's condition, such as glucose levels;

• smart clothing – to track vital signs and physical activity. For example, a Canadian company Hexoskin already produces T-shirts with sensors that monitor the quality of breathing, physical activity of a person, and heart rate indicators.

At the beginning of 2024, Pragmatic Semiconductor launched its own production of flexible chips, the cost of which will be approximately one dollar. So, perhaps soon we will actually see smart milk bags on the shelves that will transmit data to the database that it has turned sour.

So what awaits us?

The table compared the latest flexible chips with the A16 Bionic chip found in the iPhone 14 Pro.

It is clear that the performance of traditional chips is thousands of times higher than that of flexible ones. But existing samples are flexible and do not pretend to work in smartphones and other complex devices. But for everyday tasks in medicine, retail, and logistics, flexible microprocessors are quite suitable. For example, these were used by an Australian startup in its development – electronic headband on the head for people with ADHD. It provides mild electrical stimulation to the brain and can replace medications taken for ADHD.

Experts who study flexible electronics, thinkthat the technology has a great future. The chips will be used in smartphones, and then they can be worn as a wide bracelet on the wrist. Or in robotics, so that robots can better sense the environment and their own body – almost the same as a person.

But potential users of devices with flexible chips react differently. For example, Russian users are afraid that smart products will monitor them and “push” advertising:

Europeans are more concerned about the environmental friendliness and recyclability of flexible chips, especially if they are used in packaging and medical products, because in this case the chips will be practically disposable.

In the team's opinion mCloudsflexible chips are not such a fantasy, they can enter the market en masse in just a couple of years. What do you think about this?