14 Apr 2019 by Margaret Harris

Photo of rows of lithium-ion cells
Prototype lithium-ion cells made by Sila Nanotechnologies, which the company claims have a 20-40% higher energy density than conventional cells. Image courtesy of Sila Nanotechnologies.

Silicon nanomaterials that squeeze 40% more energy into batteries. A smart watch that gives people with diabetes a pain-free way of tracking their blood glucose levels. “Smart” sensors that help prevent repetitive strain injuries and diagnose faults in remote equipment. A replacement for toxic chemicals in flame-retardant materials. These are just a few examples of the innovations discussed in Berlin last week at IDTechEx Europe, an annual conference that focuses on some of the hottest topics in science and technology.

On 10 April, while the rest of the physics community (judging from Twitter, at least) was cooing over the first image of a black hole, scientists from two start-up companies, SiLiBand Sila Nanotechnologies, outlined their plans for manufacturing lithium-ion batteries with silicon anodes instead of conventional graphite ones. The idea of replacing graphite with other materials, including silicon, isn’t new, and it’s easy to see why it’s attractive: the specific capacity (roughly, how much energy a material can store) of silicon is 4200 milliamp hours per gram (mAh/g), compared to graphite’s measly 372 mAh/g. Other factors, such as the make-up of the cathode, limit the expected improvement in storage capacity to 40% rather than a factor of 10, but that’s still significant. I’d love it if my mobile phone battery lasted 40% longer, and an electric car that travelled 40% further between charges would be a game-changer for many consumers.

There’s a problem, though: silicon anodes swell and shrink by up to 300% during charge-discharge cycles, causing irreversible damage to the battery. SiLiB’s solution is to make its anodes from silicon nanowires grown on an ultrathin stainless-steel mesh that is flexible enough to cope with the swelling. The results seem promising: CEO Arnon Blum presented data showing that SiLiB’s batteries retain 70% of their capacity after 300 charge cycles, and there were audible sighs of disappointment from the audience when he said that the product is still in development.

Sila Nanotechnologies, in contrast, hopes to launch its first commercial product later in 2019, albeit for smart watches rather than the electric vehicles its CEO (Gene Berdichevsky, an early Tesla employee) had in mind when he co-founded the company in 2011. Sila’s anodes are made from a silicon-dominant nanocomposite material, and while the company’s business-development manager, Craig Weich, declined to give details (“My slides were a lot more interesting before our IP folks reviewed them,” he joked), the basic idea is that the nanocomposite incorporates enough space in its structure for the silicon to swell inside it. According to Weich, the main thing delaying the material’s commercial roll-out is that it’s difficult to manufacture it in large quantities – which is why Sila is targeting the market for smart watches rather than mobile phones or electric vehicles.

Pain-free glucose monitoring

Another company hoping for a piece of the smart-watch market is PKVitality, a Paris, France-based start-up that aims to give people with diabetes a pain-free way of monitoring their blood glucose levels. PKVitality’s smart watch fits over (and communicates with) an adhesive patch containing millimetre-long microneedles that sample the interstitial fluid in the upper layers of the skin. This interstitial fluid reacts with glucose oxidase enzyme in the patch, liberating electrons and making it possible to infer blood glucose values from the resulting electric current. Because nerves in the wrist are more than 1mm below the surface, PKVitality CEO and founder Luc Pierart claims that applying the patch is no more painful than running a fingernail over the skin – a huge improvement over the several-times-daily fingerprick tests that most people with diabetes use to monitor blood sugar.

Photo of a watch with an adhesive patch underneath it.

PKVitality’s watch isn’t commercially available yet, and some aspects of it still need work. During the question-and-answer session, Pierart acknowledged that the watch needs to be worn pretty much continually to keep the patch in place and avoid damaging the microneedles. Its accuracy as a glucose monitor has also so far only been tested in animals. However, a preliminary study on pigs found that blood-glucose results were 99% accurate, and Pierart claims that the smartwatch interface also helps to reduce the stigma that some people with diabetics feel when using fingerprick tests and conventional glucose monitors.

Sensors for the workplace

Another company that aims to use innovative sensors to reduce pain is Myontec, a Finland-based start-up founded by a physicist, Pekka Tolvanen. Myontec bills itself as “the world’s first comprehensive out-of-the-lab muscle monitoring system provider”, and its system consists of a shirt and shorts fitted with conductive textile sensors that measure activity in 14 muscle groups at once. A mobile app records data on the wearer’s movements, and by comparing these data to reference data, Tolvanen claims that Myontec’s scientists can identify potential causes of repetitive-strain injuries.

Work-related musculoskeletal disorders are a major contributor to global ill health, and they also cost the world’s economy around €400bn a year in lost work time. Tolvanen has calculated that Myontec’s services could save a 1000-employee company up to €1.5m a year in reduced sick days, and he and his colleagues have carried out several test projects. In one study, Myontec’s experts found that the forearm muscles of workers in a meat-cutting factory were being heavily overloaded by the long-bladed knives they had to use. After the factory’s owner switched to medium-sized blades, instances of carpal tunnel syndrome among workers fell by 100%.

Reducing pain isn’t the only way that smarter sensors can improve people’s lives. On the conference’s second day, I spoke to scientists at a start-up called Flicq that makes sensors for industrial installations. According to business development manager (and physicist-by-training) Ikenna Gaius, Flicq’s sensors make it possible to identify and diagnose problems with machinery remotely, rather than waiting for the apparatus to fail or sending out engineers to perform maintenance on a fixed schedule. For equipment in hard-to-reach locations, that can be a godsend. Gaius’ previous career was in the oil and gas industry (he describes himself as an “oilhead” rather than a physicist), and he told me that he once had to fly an engineer out to an oil rig just to change a fuse. This, he says, was “crazy”, and he doesn’t like to think about how much it cost.

Humble products, big rewards

Curiously enough, both Myontec and Flicq started out by making sensors for athletes before deciding to enter the market for industrial applications. Hearing this put me in mind of another stand-out IDTechEx talk, this one on graphene. As the speaker, Nikolaus Nestle, pointed out, many of the first commercial applications of graphene were in high-end sporting goods such as running shoes and golf balls. For some of these products, adding graphene made a real, measurable difference to performance. For others, however, it was essentially a marketing gimmick, one that risked undermining graphene’s reputation.

Nestle – a physicist and principal scientist at BASF Advanced Materials and Systems Research in Ludwigshafen, Germany – thinks that some of the most promising future applications of graphene will instead be found in unglamorous areas that don’t get much attention in scientific papers. One example is flame-retardant materials. Existing flame-retardant additives are pricey and sometimes toxic, and a growing body of evidence suggests that graphene could be a workable replacement. Although no-one is entirely sure why graphene inhibits the spread of flames, one possible explanation is that the material’s structure creates a “labyrinth effect” that prevents combustible gases from escaping. Applications like these, Nestle thinks, could be just the thing to shift graphene out of the proverbial “valley of disappointment” and onto the “plane of productivity” – thus keeping it among the hottest topics in science for years to come.

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