More disruption ahead: Wireless sensors that can be printed at home

What does this mean for companies that have built their own disruptive tech offerings around wireless sensors? Maybe less than you'd think.


A prototype of Thinfilm's smart wine bottle.

Credit: Thinfilm

3D printing is now synonymous with disruption innovation.

A stroll through the RAPID 3D Conference earlier this year would have told you that, if the daily industry and business news headlines haven't.

But if you have been paying close attention to the issue, you would have noticed a common theme: Few, if any, of these 3D-printed products involve micro-electromechanical systems.

So sure, you've got your 3D-printed prosthesis parts, drones, even electrical cars. But, the basic electrical components, such as wireless sensors, tend to be manufactured via traditional means.

Now, that doesn’t mean such components can't be printed. Thinfilm, a printed electronics specialist headquartered in Oslo, Norway, is turning heads with its near field communication sensor-based products, such as the debut earlier this year of a "smart" Johnnie Walker Blue Label whiskey bottle.

But, as they might say, this has not been something you could try at home.

Now, UC Berkeley engineers say they have cracked that particular nut. Their proof of concept is a smart cap for a container of milk that can show if it has spoiled — which is an interesting, if not ironic example, as that is the one of the use cases that Thinfilm is also targeting.

UC Berkeley engineers collaborated with Taiwan’s National Chiao Tung University on this project. The study was published in a Nature Publishing Group journal called Microsystems & Nanoengineering.

"Our paper describes the first demonstration of 3D printing for working basic electrical components, as well as a working wireless sensor," said senior author Liwei Lin, a professor of mechanical engineering and co-director of the Berkeley Sensor and Actuator Center.

"One day, people may simply download 3D-printing files from the Internet with customized shapes and colors and print out useful devices at home."

Let's look at what Berkeley has done.

How to build a smart cap from scratch

The first issue the researchers tackled was the unfortunate fact that polymer, which is a very popular material for 3D printing because of its flexibility, is a poor conductor of electricity.

So the researchers built a model using polymers and wax. The wax was removed when it hardened, leaving behind hollow tubes into which liquid metal was injected and then cured. Thin wires were crafted into resistors, flat plates into capacitors. Add a plastic milk cartoon cap plus inductor to the equation and, voilà: a resonate circuit.

Then, with a flip of the carton, a bit of milk entered the capacitor gap. The final step: leaving the milk carton out on the counter for 36 hours. Which never happens in anyone's house ever.

This was the experiment's result, according to the researchers:

The circuit could detect the changes in electrical signals that accompany increased levels of bacteria. The researchers periodically monitored the changes with a wireless radio-frequency probe at the start of the experiment and every 12 hours thereafter, up to 36 hours. The property of milk changes gradually as it degrades, leading to variations in its electrical characteristics. Those changes were detected wirelessly using the smart cap, which found that the peak vibration frequency of the room-temperature milk dropped by 4.3 percent after 36 hours. In comparison, a carton of milk kept in refrigeration at 39.2 degrees Fahrenheit saw a relatively minor 0.12 percent shift in frequency over the same time period.

Success, in other words.

"This 3D-printing technology could eventually make electronic circuits cheap enough to be added to packaging to provide food safety alerts for consumers," said Lin. "You could imagine a scenario where you can use your cellphone to check the freshness of food while it’s still on the store shelves."

In point of fact, that scenario has already been imagined. More importantly, though, it has been commercialized. One doesn't always lead to the other.

Thinfilm's smart prototype of Diageo's Johnnie Walker Blue Label whiskey bottle? It was equipped with a printed NFC sensor tag supported by Thinfilm's new OpenSense technology to track the bottle. The consumer taps his or her smartphone to the tag on the bottle, which is encoded at the manufacturing site, to find out if the bottle has been opened or not and where it originated in Diageo's supply chain.

Still a dream

The many moving parts necessary to this product's rollout suggests that this is not something that can be done at home.

Consider just the manufacturing process for Thinfilm Memory, the company's printed memory. It describes it on its website:

We begin with a thin, inexpensive plastic (PET or PEN) for our substrate. On the plastic substrate, we gravure print our bottom electrode, then coat a layer of ferroelectric polymer. Next, we use a second gravure print station to add our top electrodes, followed by screen printing a series of carbon pads. Carbon is a cost-effective way to expand the contact area available on the memory labels. Finally, two patent-pending protection layers are printed via rotary screen.

It is all done on a single, multistage press at InkTec, the company's partner production site in Korea. The finished rolls are converted to labels via industry-standard converting methods.

Customized components

To be fair, the Berkeley researchers are not claiming that their wireless sensors can be built at home right now. Or even, for that matter, in the foreseeable future.

Challenges include the extremely small size of modern electronics. Also, as Lin noted, home production of these sensors would not be cost-effective "since current integrated circuits are made by batch fabrication to keep costs low."

This is where the Berkeley-National Chiao Tung University project has great potential, though: individual, one-off customized sensors for very specific 3D-printed microelectronic devices that would cost a great deal to manufacture otherwise.

Testing for health applications comes to mind, and indeed, Lin's team is currently working on developing an implantable device with an embedded transducer that can monitor blood pressure, muscle strain and drug concentrations.

Smart wine companies need smart bottles

Here's the issue with emerging technology: It is very easy to get wowed by the proof-of-conceptness of it all, but in the end these products need to find commercial homes — and commercial users — to have any kind of real impact.

Thinfilm, you see, is not bringing its products to market in isolation; it first had to convince other companies of its potential so that it could scale it out.

Thinfilm's latest endeavor is a smart wine bottle — a product for which the G World Group, an authentication company specializing in transparency and accountability solutions, recently placed a seven-figure unit order.

G World will be offering an anti-counterfeiting solution powered by Thinfilm’s NFC technology to authenticate individual bottles throughout the supply chain.

Its first destination is China, where stats show 50% to 70% of all wine sold in the country could be fake. The percentage is even higher for premium brands.

The cost per bottle of using this solution is not very high, Jennifer Ernst, Thinfilm’s Chief Strategy Officer, tells me — perhaps 20 cents to 30 cents per bottle. There are alternative on the market, she notes, such as an inserted cap mechanism. However these deter only certain discrete activities, such as the refilling of the bottle with a counterfeit wine.

Nor are they cheaper — and perhaps more to the point for wine companies, they don’t offer end-to-end protection that G World is promising, from packaging, shipping, stocking and to the end purchase, where the buyer opens the wine in its original factory-sealed state.

It is a new world indeed — new enough that even first adopters such as G World require a financial commitment from its own customers before setting out.

That seven-figure unit order was placed on behalf of Ferngrove Wine Group, a Chinese-owned, Western Australia wine company that supplies premium red wine to the Asia-Pacific region and exports more than 600,000 bottles annually to China alone.

First, though, Ferngrove will field-test the smart wine bottle before it makes further financial commitments. And so it goes.

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