flexible electronics

Recent breakthroughs in printed and flexible electronics herald a whole new age of gadgets, imaging devices and user interfaces.

The nature of the underlying electronics needs to change as our computing requirements change. We’re moving into an era of wearable gadgets that require flexibility and new user interfaces – and there are many advances required to make that happen.



Some of those advances were on show last week at IDTechex’s Printed Electronics Europe show in Berlin, which as usual also took in events dedicated to other narrow fields such as graphene and energy harvesting (on which I reported last year). The stuff on show this year was particularly mind-blowing.

One of the most impressive technologies was this, from ISORG and Plastic Logic (remember them?) — a flexible image sensor that won the show’s product development award:


In that setup, a small picture of the Mona Lisa is resting directly on the sensor, which combines Plastic Logic’s flexible transistor technology (underneath) with ISORG’s organic photodetector technology (layered on top). The large-area sensor is directly reading and transmitting the picture, with minimal thickness and weight. You couldn’t do that with a standard CMOS imaging sensor, for example, because that needs a minimum distance for focalization.

The potential applications are wide-ranging. Imagine sticking an evolution of that sensor behind a tablet screen, for example: you’d turn the screen into a scanner (perfect for receipts, perhaps) and a fingerprint reader (bye-bye dedicated modules like Apple’s TouchID), but you’d also unlock a whole new era of gesture control. The sensor uses infrared and it can read things that are close to but not touching the screen, as ISORG demonstrated with this arrangement:


Here, the company ripped open a standard, non-touch LCD monitor and stuck a sensor array directly behind part of the screen. In this picture, the software is tracking a finger that’s moving just in front of that part of the screen without touching it, with pretty impressive sensitivity and in three dimensions.

Contactless controls have great potential in the medical field, which ISORG will target first, but also in consumer electronics and even connected but screen-less items – think of the implications for internet-of-things devices and logistics (smart scanning stock shelves, for example). The technology could also be used to create user interfaces for wearable devices, and it would certainly make copiers and scanners much thinner by replacing their bulky, moving CCD arrays.

As Laurent Jamet, co-founder of the Grenoble, France-based ISORG, said in a presentation: “It was difficult to think a couple of years ago that a piece of plastic would become a camera, but that is now the reality.”

And speaking of screens that can read stuff:


This is very low-tech compared to the flexible imaging sensor, but it’s interesting nonetheless. It’s a system called Touchcode, from T+Ink, that seeks to replace relatively pricey RFID technology in some use cases. With RFID, you have to embed electronics into your travel card or keyfob or whatever – here, you just use conductive ink, which is cheaper, thinner and more flexible, to transmit information to the reader.

The best thing about this system is that the reader can be found in any modern mobile device: the screen. Capacitive touchscreens usually work because of the conductivity in your finger; here, they just read the conductive pattern of the ink on the smart card, smart packaging or what have you. In this example, holding the promotional “Cars 2″ card over the suitable app brings up an image of the relevant car. It’s a darn sight easier to use – and more pleasing to the eye – than a QR code that needs to be held in front of the phone’s camera.

Back to proper printed electronics now. Here’s a flexible temperature sensor array from PST Sensors, a spinoff from my alma mater, the University of Cape Town in South Africa:


This is cool – excuse the pun – for a couple of reasons. First off, PST prints with proprietary silicon nanoparticles that it can stick into a variety of ink types and therefore use on pretty much any surface (PST has a patent on printing electronics onto paper). Silicon is abundant and cheap, and perfect for printing electronics, such as temperature sensors, onto packaging.

Sensor arrays of the type shown above could be used to cover wide areas and record specific temperatures at specific points – at PST’s stand, one array was designed for chemists working with a bunch of test tubes; they could put the lot onto one array and take temperature readings for each specific tube.

PST claims it can make a temperature sensor of any size or shape and put it anywhere. As founder David Britton said: “The benefit of printing electronics isn’t cost; the benefit of printing is form factor.”

That was definitely a recurring theme at the show. Check this out:


This is from a company called, somewhat unimaginatively, Printed Electronics. The firm, with clients ranging from the aerospace to the automotive sectors, was tasked by a customer with developing a method of printing electronics onto any 3D surface. It did so and is now trying to find other applications. In a move close to my heart, they demonstrated their capabilities by printing a circuit, microcontroller and temperature sensor directly onto a standard wine bottle, along with LEDs – a very smart system for high-end wines that will be stored, if you ask me.

“We did that because we didn’t know what else to print,” senior electronics design engineer Leon Giquel said.

Or how about this – light sensors for blinds are not a new idea, but they don’t tend to be integrated into the blind itself:


That one’s from the Holst Centre in Eindhoven, the Netherlands. The organic photo diodes can sense incoming light and adjust for more or less exposure. The center is also working with chemicals giant DuPoint and others on flexible plastic OLED lighting:


Finally, to make a brief foray into the energy-harvesting side of the show, I was very impressed with these switches from Swiss input tech specialist Algra. They operate using piezoelectricity – a tiny plate inside the switch registers pressure of just a few micrometers and uses it to generate just enough juice to send out a wireless signal:


That means the switches don’t require any battery or external power, and they can accordingly be built into all sorts of furniture and other items. Because they have no moving parts as such – you don’t feel a tactile click or anything – they also have an extremely high mechanical lifetime. One implementation shown in the picture involves a system that could be built into a restaurant table for calling waiters, who would wear some kind of wearable device to see who needs them.

In short, thin has always been in, but the technology is now getting so thin and flexible that the future looks bright for new form factors, user interfaces and applications. You can see tangible progress from year to year, and it’s all rather exciting.

Via Gigaom