Make Way For Flexible ICs

The push to develop intelligent sensors everywhere does not require everything to be on a silicon substrate. In fact, a growing part of the market increasingly is focused on flexible substrates.

The market for printed sensors is roughly $3.6 billion today, according to a new report by IDTechEx. In a decade, that number is expected to grow to $4.5 billion, according to the firm, with growth in hybrid image sensors increasing from less than $1 million today to $800 million in a decade.

While that may not seem like a huge top line number, these are not $100 processing elements. Typically they are printed on rolls of plastic and sold for pennies or less, much the way newspapers are printed, which is why the chip industry has largely ignored this space. Unlike developing chips at 7/5/3nm by shooting lasers through droplets of falling tin or controlling atoms of dielectrics, the majority of flexible circuits look like the kind of chips you’d find in a greeting card.

Neveretheless, the value of flexible substrates is growing, particularly for applications where a block of silicon or some other hard substrate doesn’t work. This is obvious for wearable electronics, and in industrial applications such as a valve, where developing a variety of sensors to measure things like flow and vibration are deemed too expensive in quantities of less than 1 million. A standard, off-the-shelf bundle of sensors glued to a piece of tape is much more economical, and it can be replaced as easily as putting on a new piece of tape.

This hasn’t gone unnoticed. Companies are beginning to look at just how these devices perform over time and under stress. Complex ink chemistries are under development, and more sophisticated patterning techniques on flexible materials other than just plastic are just beginning to gain ground.

Case in point: Researchers at Australian National University have discovered a novel organic material that is one atom thick and flexible. What makes this example particularly interesting is it can be used for optical as well as electrical signals, which makes it not only lightweight and cheap, but also very fast and extremely low-power. The researchers see this as essential in flexbile mobile phones, but that may be just scratching the surface.

What’s needed next is the same kinds of predictability built into these processes that everyone now expects from silicon chips. As flexible substrates begin showing up in more devices and applications, they almost certainly will become more complicated than strands of wire bonded to a piece of fabric or plastic. Understanding of how noise and other proximity effects will impact signals, and how various physical bending and handling will impact reliability over time are still largely absent from this part to the market, but they’re coming.

There are no studies into the stochastics of inkjet printing of circuits, because few if any have been used for critical applications so far. But as these devices become more capable and more widespread, that’s likely to change.

Whether the current chip industry will embrace this as an opportunity, or whether a separate market will grow up on its own, remains to be seen. But what’s clear is this market segment is beginning to get much more interesting, and as it becomes more established it may become an integral part of more complex system design. At that point, it had better work as expected.

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