DIY Chemistry Points The Way To Open Source Blood Glucose Testing

January 4, 2024 by 16 Comments

Every diabetic knows that one of the major burdens of the disease is managing supplies. From insulin to alcohol wipes, diabetes is a resource-intensive disease, and running out of anything has the potential for disaster. This is especially true for glucose test trips, the little electrochemical dongles that plug into a meter and read the amount of glucose in a single drop of blood.

As you might expect, glucose test strips are highly proprietary, tightly regulated, and very expensive. But the chemistry that makes them work is pretty simple, which led [Markus Bindhammer] to these experiments with open source glucose testing. It’s all part of a larger effort at developing an open Arduino glucometer, a project that has been going on since 2016 but stalled in part thanks to supply chain difficulties on the chemistry side, mainly in procuring glucose oxidase, an enzyme that oxidizes glucose. The reaction creates hydrogen peroxide, which can be measured to determine the amount of glucose present.

With glucose oxidase once again readily available — from bakery and wine-making suppliers — [Markus] started playing with the chemistry. The first reaction in the video below demonstrates how iodine and starch can be used as a reagent to detect peroxide. A tiny drop of glucose solution turns the iodine-starch suspension a deep blue color in the presence of glucose oxidase.

While lovely, colorimetric reactions such as these aren’t optimal for analyzing blood, so reaction number two uses electrochemistry to detect glucose. Platinum electrodes are bathed in a solution of glucose oxidase and connected to a multimeter. When glucose is added to the solution, the peroxide produced lowers the resistance across the electrodes. This is essentially what’s going on in commercial glucose test strips, as well as in continuous glucose monitors.

Hats off to [Markus] for working so diligently on this project. We’re keenly interested in this project, and we’ll be following developments closely. Continue reading “DIY Chemistry Points The Way To Open Source Blood Glucose Testing” →

Sandpaper Alternatives For 3D Prints

January 4, 2024 by 19 Comments

A finished 3D print, especially plastic deposition types, often have imperfections in them from the process of laying down each layer of material and from the printer itself. For small batches or one-off parts, we might reach for a few pieces of sandpaper to smooth out these rough edges. While that might work for a small number of parts, it’s not always the best or lowest-effort option for refining these prints. There are a few alternative methods to try out if your fingers are getting sore, though.

Rather than removing material as sandpaper does, most of these methods involve adding material to the print in order to fill in the rough edges of the print. There is a 3D-print-specific product listed called 3D Gloop! which is generally used as a glue to hold plastic parts together, but can also act as a fill in a pinch. Two other similar methods, one using spray paint and polyurethane and the other using epoxy, are more general-purpose ways of finishing the prints with a more natural texture than the printer will produce on its own. They’re not all additive, though; the final (and perhaps, most toxic) method here to achieve a smooth surface on a print uses solvent to remove some of the material instead.

While sandpaper does have its time and place, certain prints may lend themselves more to being finished by one of these other methods especially if they are overly complex, fragile, or an unusual size. Take note of the safety gear you’ll want to have on hand for most of these methods, though, as gloves and a respirator are highly encouraged and possibly helpful even if using only sandpaper. These aren’t the only ways of finishing 3D prints, either. Some of our other favorites are using glazing putty or silver for the finish.

The World Of Web Browsers Is In A Bad Way

January 4, 2024 by 115 Comments

There once was a man who invented a means for publishing scientific documents using hypertext. He made his first documents available from his NeXT cube, and a lot of the academics who saw them thought it was a great idea. They took the idea, expanded it, and added graphics, and pretty soon people who weren’t scientists wanted to use it too. It became the Next Big Thing, and technology companies new and old wanted a piece of the pie.

You all know the next chapter of this story. It’s the mid 1990s, and Microsoft, having been caught on the back foot after pursuing The Microsoft Network as a Compuserve and AOL competitor, did an about-turn and set out to conquer the Web. Their tool of choice was Microsoft Internet Explorer 3, which since it shipped with Windows 95 and every computer that mattered back then came with Windows 95, promptly entered a huge battle with Netscape’s Navigator browser. Web standards were in their infancy so the two browsers battled each other by manipulating the underlying technologies on which the Web relied. Microsoft used their “Embrace and extend” strategy to try to Redmondify everything, and Netscape got lost in the wilderness with Netscape 4, a browser on which nightmarish quirks were the norm. By the millennium it was Internet Explorer that had won the battle, and though some of the more proprietary Microsoft web technologies had fallen by the wayside, we entered the new decade in a relative monoculture. Continue reading “The World Of Web Browsers Is In A Bad Way” →

How Good Is The Cheapest Generator On Amazon?

January 4, 2024 by 79 Comments

Although an internal combustion engine-based generator isn’t exactly one of the most complicated contraptions, any time that you combine something that produces power with electrical devices, you generally like to know how safe it is. Even more so when it’s a $139 generator you got off Amazon, like the PowerSmart 1200 Watt (1000 continuous) that the [Silver Cymbal] took a gander at recently. They used an expensive professional power analyzer to look at more than just the basic waveform of the 120 VAC output to figure out what kind of devices you’d feel comfortable connecting to it.

Waveform analysis of the cheapest generator when under load. Looks better than with no load attached.

On the unit there is a single AC output, which a heater got attached to serve as a load during testing, but before that, the properties out of the output voltage were analyzed without any load. This showed a highly erratic waveform, as the generator clearly was unable to synchronize and produced a voltage within a wide range, immediately disqualifying it for connecting to sensitive electronics. Things got less dire once the load was hooked up and turned up to use up a big chunk of the available continuous power.

Although being far from a perfect sine wave, the output now looked much better, with all properties including the total harmonic distortion (THD) being just a hair over 20% and hitting just over 60 Hz on the frequency.

Definitely not a great result, but as a cheap unit to keep around for powering things like heaters and power tools that aren’t too fussy about how clean the power is, one could do a lot worse.

Continue reading “How Good Is The Cheapest Generator On Amazon?” →

British Hospital Blasts Through Waiting Lists By Slashing Surgeon Downtime

January 4, 2024 by 66 Comments

It feels like it doesn’t matter where you go, health systems are struggling. In the US, just about any procedure is super expensive. In the UK and Australia, waiting lists extend far into the future and patients are left sitting in ambulances as hospitals lack capacity. In France, staff shortages rage furiously, frustrating operations.

It might seem like hope is fruitless and there is little that can be done. But amidst this horrid backdrop, one London hospital is finding some serious gains with some neat optimizations to the way it handles surgery, as The Times reports.

Continue reading “British Hospital Blasts Through Waiting Lists By Slashing Surgeon Downtime” →

CH32 RISC-V MCUs Get Official Arduino Support

January 4, 2024 by 26 Comments

Like many of you, we’ve been keeping a close eye on the CH32 family of RISC-V microcontrollers from WCH Electronics. You can get the CH32V003, featuring 2 kB RAM and 16 kB of flash for under fifteen cents, and the higher-end models include impressive features like onboard Ethernet. But while the hardware is definitely interesting, the software side of things has been a little rocky compared to what we’ve come to expect from modern MCUs.

Things should start looking up a bit though with the release of an Arduino core for the CH32 direct from WCH themselves. It’s been tested on Windows, Linux, and Mac, and supports the CH32V00x, CH32V10x, CH32V20x, CH32V30x, and CH32X035 chips. Getting it installed is as easy as adding the URL to the Arduino IDE’s Boards Manager interface, though as the video below shows, running it on Linux does require an extra step or two.

So far, we’ve seen several projects, like this temperature sensor or this holiday gizmo that use [cnlohr]’s open-source toolchain. But there’s no question that plenty of hobbyists out there feel more comfortable in the Arduino environment, and if those folks are now able to pick up a CH32 and do something cool, that means more people jumping on board, more libraries developed, more demo code written…you get the idea.

Just like the ESP8266’s popularity exploded when it was added to the Arduino IDE, we’ve got high hopes for the CH32 family in the coming months.

Continue reading “CH32 RISC-V MCUs Get Official Arduino Support” →

Current-Based Side-Channel Attacks, Two Ways

January 4, 2024 by 9 Comments

Funny things can happen when a security researcher and an electronics engineer specializing in high-speed circuits get together. At least they did when [Limpkin] met [Roman], which resulted in two interesting hardware solutions for side-channel attacks.

As [Limpkin] relates it, the tale began when he shared an office with [Roman Korkikian], a security researcher looking into current-based attacks on the crypto engine inside ESP32s. The idea goes that by monitoring the current consumption of the processor during cryptographic operations, you can derive enough data to figure out how it works. It’s difficult to tease a useful signal from the noise, though, and [Roman]’s setup with long wire runs and a noisy current probe wasn’t helping at all. So [Limpkin] decided to pitch in.

The first board he designed was based on a balun, which he used to isolate the device under test from the amplification stage. He found a 1:8 balun, normally used to match impedances in RF circuits, and used its primary as a shunt resistance between the power supply — a CR1220 coin cell — and the DUT. The amplifier stage is a pair of low-noise RF amps; a variable attenuator was added between the amp stages on a second version of the board.

Board number two took a different tack; rather than use a balun, [Limpkin] chose a simple shunt resistor with a few twists. To measure the low-current signal on top of the ESP32’s baseline draw would require such a large shunt resistor that the microcontroller wouldn’t even boot, so he instead used an OPA855 wideband low-noise op-amp as an amplified shunt. The output of that stage goes through the same variable attenuator as the first board, and then to another OPA855 gain stage. The board is entirely battery-powered, relying on nice, quiet 18650s to power both the DUT and the shunt.

How well does it work? We’ll let you watch the talk below and make up your own mind, but since they’ve used these simple circuits to break a range of different chips, we’d say this approach a winner.

Continue reading “Current-Based Side-Channel Attacks, Two Ways” →