Tech In Plain Sight: Glucose Meters

If you or someone you know is diabetic, it is a good bet that a glucose meter is a regular fixture in your life. They are cheap and plentiful, but they are actually reasonably high tech — well, at least parts of them are.

The meters themselves don’t seem like much, but that’s misleading. A battery, a few parts, a display, and enough of a controller to do things like remember readings appears to cover it all. You wouldn’t be surprised, of course, that you can get the whole affair “on a chip.” But it turns out, the real magic is in the test strip and getting a good reading from a strip requires more metrology than you would think. A common meter requires a precise current measurement down to 10nA. The reading has to be adjusted for temperature, too. The device is surprisingly complex for something that looks like a near-disposable piece of consumer gear.

Of course, there are announcements all the time about new technology that won’t require a needle stick. So far, none of those have really caught on for one reason or another, but that, of course, could change. GlucoWatch G2, for example, was a watch that could read blood glucose, but — apparently — was unable to cope with perspiration.

Even the meters that continuously monitor still work in more or less the same way as the cheap meters. As Hackaday’s Dan Maloney detailed a few years back, continuous glucose monitors leave a tiny sensor under your skin and measure fluid in your body, not necessarily blood. But the way the sensor works is usually the same.

For the purposes of this article, I’m only going to talk about the traditional meter: you insert a test strip, prick your finger, and let the test strip soak up a little bit of blood.

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Hackaday Prize Entry: A Universal Glucose Meter

If you need an example of Gillette’s razor blade business plan, don’t look at razors; a five pack of the latest multi-blade, aloe-coated wonder shaver is still only about $20. Look a glucose meters. Glucose meters all do the same thing – test blood glucose levels – but are imminently proprietary, FDA regulated, and subsidized by health insurance. It’s a perfect storm of vendor lock-in that would make King Gillette blush.

For his Hackaday Prize entry, [Tom] is building what was, until now, only a dream. It’s a universal glucometer that uses any test strip. The idea, of course, is to buy the cheapest test strip while giving the one-fingered salute to the companies who release more models of glucometers in a year than Apple does phones.

As with any piece of consumer electronics, there are plenty of application guides published by the biggest semiconductor companies explaining to engineers how to use their part to build a device. After reviewing the literature from TI, Maxim, Freescale, and Microchip, and a few research articles on the same subject, [Tom] has a pretty good idea how to build a glucometer.

The trick now is figuring out how to build an adapter for every make and model of test strip. This is more difficult than it sounds, because some test strips have two contacts, some have three, some have five, and all of them are proprietary. Calibration will be an issue, but if you’re building a glucometer from scratch, that’s not a very big problem.

This is one of the most impressive projects we’ve seen in this year’s Hackaday Prize. No, it shouldn’t be the only way a diabetic tracks their sugar levels, but diabetics shouldn’t rely only on test strips anyway. If you’re looking for a Hackaday Prize project that has the potential to upend an industry, this is the one.

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