Car Science: school of hard knocks
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Hey,
Here's a new thing to worry about on a Wednesday afternoon: we are probably all a lot more concussed than we think we are. Not in the sense of, say, MotoGP riders who it turned out are impossible to identify concussions on because they are, err, always concussed. Which makes it hard to measure changes in the way they'd react if they were unusually concussed.
But concussions are a lot more regular in every day life, too. Medical professionals will tell you about this with a reasonable level of horror; hitting the back of your head on an open kitchen cupboard, standing up, is a near guaranteed concussion according to one doctor I saw a few years ago. In fact, she assumed that was what I'd done, not just discovered you can achieve head injuries in media pen as well as on track, when I went in to be like "look I don't want to be alarmist but I think I'm pretty heavily concussed."
In American football concussions are frequent and serious, the follow-up condition, second impact syndrome, leading to deaths and seriously disabling brain injuries. Cumulative, smaller impacts also lead to issues - unsurprisingly, sports like boxing come with endemic amounts of brain injuries. There is a limit, as in motorsport, on how much of that risk can be controlled without completely changing the nature of the sport and concussions are a risk anywhere, any time.
But something that would make a significant improvement is wearable - or human-contactable - materials that can take large amounts of energy out of an impact before it gets into your skull. The equivalent of tyre or tecpro barriers but for your head.
"Ok Hazel we get you've been watching Dorktown but I'm not 100% sure where you're going with this one in terms of science or cars yet." Let me cook. Or maybe, as is my job most of the week, pour you a drink here because today we're talking about nanofluidics.
A recent edition of Advanced Materials (ok, might not be that recent, I mean I still had the browser tab open) had the paper Nanoconfined Water-Ion Coordination Network for Flexible Energy Dissipation Device which immediately caught my notice partly because energy dissipation device is the kinda thing that screams Car Science. Fortunately by the time I'd finished trying to work out how to access the paper I'd also found a write up by Virginia University that explained it in words I could understand.
Anyway, my inability to see a button labelled 'download pdf' aside, this is a genuinely cool bit of technology that could have a lot of applications. You won't be surprised, probably, given the Varsity sports industrial complex in the US, that a lot of effort goes into studies to develop materials that protect American football players' heads better.
Now uh, I'm gonna try one of the science bits where I use a bunch of words that hopefully are in the right order so stand back everyone.
The background to all this
There was a prior study published in 2020, from the University of Michigan, that used a highly porous nanofoam, coated in a hydrophobic layer to prevent it absorbing water, as a structure to contain saltwater well enough that, when impacted the water was forced into the porous layers and pressurised, absorbing the energy of the blow.
The nanofoam can't absorb the water, the water can't go anywhere and because they're so uhhhh scrunkled (technical term - 1 gram of this nanofoam could cover the area of a stadium) that creates a complex version of what happens in a Tecpro barrier, basically.
What happens in a Tecpro barrier?
Tecpro barriers are things you absolutely must resist the urge to kick if you're at a motorsport track because when you see a car hit them they look quite squishy but when you toe hits them. Well, they are not.
They're flexible barriers, the outside of which is made of a polyethylene plastic, lined with metal and then filled with foam and straps to keep them together. Then some of the polyethylene blocks (in specific formations) are filled with nothing, to create another absorbent space. The gaps between the things in them and the barriers themselves absorb the energy of a high speed impact, using the force to compress the air in the gaps and also out of the foam.
That works fine if you're stopping a car that already has the human in it strapped into a survival cell and with their head safely ensconced in a helmet. What happens in American football - or road car accidents - is a little bit different.
A Tecpro barrier is about as tall as my shoulders and the span of one of my arms across, which is the kind of stupid measurement that shouldn't be in a newsletter about science but you get the idea. It would take a lot more than 1 gram of them to cover the area of a stadium. But like, as hugely crude metaphors go they are somewhat doing the same thing.
What's this new stuff then?
Well, like many energy drinks you've been sold over your lifetime: it's enriched with ions. Unlike many energy drinks you've been sold during the desperate and hungover moments of your lifetime it actually does something with them more than just dupe you into believing this will help faster than non-ionic confined nanofluidic materials would.
To not get too lost in the science, the principal is fairly the same as the 2020 paper (huge surface area on a highly porous nanofoam creates pockets of water in said pores under pressure, due to the nanofoam being water-resistant) but this one is ion-doped, which means there's things that carry charge (electrons and protons) in there.
So far, so all-new Voss edition that I'll no doubt be purchasing the next time I am, in fact, critically hungover. But this stuff can also stop your head hurting in other ways. Because adding the ions means that the water behaves differently in a whole bunch of curious ways, including dissipating pressure and stopping the water turning into a gas or freezing. Which, like, let's not get into it but water acts completely out of pocket under pressure, in confined nanospaces and you get extreme phase transition temperatures like freezing at 151C. We don't want to think about that but there is a paper about it here.
The most important thing is that water moves faster when it's interacting with ions, so that the material both doesn't form a rigid shape when absorbing energy and it means that it responds to impacts in the microseconds during which they happen.
ANYWAY. Ions: good at dispersing energy at the same time as the water and the scrunkled nanofoam is doing some of the rest of the heavy lifting there. So what this can do is repeatedly withstand heavy impacts without breaking, meaning that it would be suitable for eg: sports equipment where athletes take multiple hits per game and might not realise the first one had compromised their protection.
This is all an evolution of the Michigan study (in fact the lead from that is a collaborator on the Virginia paper) and it's an important development because this foam is lighter, more compact and more plausibly wearable so could start making a big difference to athletes in sports with head impacts.
And also, car headrests.
Look mum no HANS
The HANS device has saved a lot of lives in motorsport by keeping drivers' heads attached to their shoulders. Likewise, motorsport headrests use specific sorts of foam to absorb the impact if a drivers' helmeted head hits the top of the cockpit.
There aren't helmets or HANS devices in road cars. What there is is what's commonly misunderstood to be the car headrest - in fact, it's just a cushioned head-restraint in case of an impact.
Crude though it is, it saves lives and if it could absorb more of the energy of a back-of-skull impact, it'd save even more. One of the uses identified by the scientists for these studies was that as EVs have higher acceleration (due to electric torque) and deceleration (due to regenerative braking) there are more hard stopping incidents where you're likely to just bump your head on the head restraint.
This nanofoam could absorb those hits and go back to normal, so that in the event of a major crash it was still available as protection. Also the car industry buying into it would, of course, both be convenient for scientists who need funding and something that would make scaleable production much more realistic.
Anyway: dissipating energy, it's more exciting than you think. Now I better go get dressed and dissipate some bar fights or whatever at work.
Stay safe innit,
Hazel
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