fit_bit

The full announcement of the Fitbit recall has hit the Consumer Product Safety Division site, and it’s a useful reminder that while we might think we’re reinventing the wheel, sometimes that round shape really is the best solution. Another way of making the same point is to try to remind the Valley’s engineers that other, earlier engineers have indeed existed, and some of them were pretty shit hot at solving problems.

We’re all still a bit unsure as to exactly what the problem is with the current design, but I’m going to go out on a limb and declare that it’s nickel dermatitis. Here are the actual numbers:

The firm has received about 9,900 reports of the wristband causing skin irritation and about 250 reports of blistering.

That’s out of apparently 1 million pieces that are out there in the marketplace. Some people are naturally sensitive to nickel, others become sensitized by exposure. As a result, over here on this side of The Pond we’ve rules about how much nickel is allowed to escape from something that people are wearing:

The Nickel Directive imposes limits on the amount of nickel that may be released from jewellery and other products intended to come into direct and prolonged contact with the skin. These limits, known as migration limits, are:

0.2 µg/cm2/week for post assemblies which are inserted into pierced ears and other pierced parts of the human body;
0.5 µg/cm2/week for other products intended to come into direct and prolonged contact with the skin.

Over here we know that anything called a “Directive” comes from the European Union, which is why it is amusing that Euro coins significantly breach these limits. The combination of their bimetallism and human sweat causes the nickel to migrate above those limits. But other than noting that the EU is trying to murder us in our beds there’s not much we can do about it.

The other part of the story is this from Pando earlier:

But when Park and fellow founder Eric Friedman had the idea for a wireless-enabled wearable device that tracks a user’s daily activity, energy output and sleep quality, the only comparable product was a $25 pedometer, they had no manufacturing skill set and knowledge about how to make hardware was closely guarded.

‘It was all trade secrets locked away in the bowels of companies like Apple,’ Park says.

Fitbit was founded in April 2007. ‘The dark ages of hardware,’ as Clavier describes it.

They designed their hardware through a great deal of trial and error, and didn’t get it right the first time around. That’s okay. That’s what happens in hardware design. Before I make this next statement, I will admit I am assuming the problem is nickel dermatitis, but I’m not 100 percent certain that it is. Assuming that, I think this is an interesting example of one of the problems the Valley might have in general.

Yes, we all know it’s the center of all the bright people on the planet. But that doesn’t mean every solution to everything was wrong before the Valley came into being. With everyone and their grandmother looking at wearables, it’s worth mining some of that earlier information from the jewelry market.

For example, we all know we’re not going to make gadgetry out of straight iron, we know that will rot away too quickly. The usual next step up from that is to use nickel steel. However, that is contra-indicated when it is to be used to make something that will have prolonged contact with human skin. Other formulations of steel must be used (and here my knowledge gets a bit hazy, but I think that it’s usual to use high-chrome steel).

If it turns out not to be nickel dermatitis at Fitbit, then the logic I’m using here is going to seem a bit tottery. However, I do still think there’s an important point to be made. The grander one is that certain problems have already been solved and designers of new shiny shiny — such as wearables — should research the problems and how they were solved. We know quite a bit about the interaction of certain metals and the human skin. This isn’t something that computing designers have had to worry about. Now with wearables they do. So go talk to the jewelry business and find out what they know.

For example, you want to use low nickel steels. You don’t want a bimetallic, especially if a piece containing nickel will be worn by sweaty people (please note that bimetallic here means two separate metals or alloys next to each other, rather than two or more metals mixed into an alloy. The reason is that sweat will turn them into a battery thus accelerating the movement of metallic ions).

It’s worth looking at the metals used for body implants: Titanium is extensively used in joints for example, and niobium is the metal of choice for nipple rings and all the rest. And assuming that wearables really do take off into a mass market device, there will almost certainly be a niche for those who make hypo-allergenic versions of them. Some people are sensitive to alloys that cause 99 percent of us no problems at all. The usual solution is a bit of rhodium plating, which is common in earrings.

I’m not trying to jump up and down with glee at the Fitbit problems, rather to use it as an illustration of how it might be sensible for the designers of new to look at how the designers of old solved the same problems. One of these being the interaction of humans with various metals and their alloys.

My specific piece of advice to those trying to design wearables would be to go find yourself a decent graybeard jewelry designer and find out what we’ve collectively learned about the alloys that you can place in close proximity to skin. This could save you a lot of money.