MEMS

43 Articles

Laser Theremin Turns Your Hand Swooshes Into Music

October 3, 2021 by 10 Comments

In a world where smartphones have commoditized precision MEMS Sensors, the stage is set to reimagine clusters of these sensors as something totally different. That’s exactly what [chronopoulos] did, taking four proximity sensors and turning them into a custom gesture input sensor for sound generation. The result is Quadrant, a repurposable human-interface device that proves to be well-posed at detecting hand gestures and turning them into music.

At its core, Quadrant is a human interface device built around an STM32F0 and four VL6180X time-of-flight proximity sensors. The idea is to stream the measured distance data over as fast as possible from the device side and then transform it into musical interactions on the PC side. Computing distance takes some time, though, so [chronopoulos] does a pipelined read of the array to stream the data into the PC over USB at a respectable 30 Hz.

With the data collected on the PC side, there’s a spread of interactions that are possible. Want a laser harp? No problem, as [chronopoulos] shows how you can “pluck” the virtual strings. How about an orientation sensor? Simply spread your hand over the array and change the angle. Finally, four sensors will also let you detect sweeping gestures that pass over the array, like the swoosh of your hand from one side to the other. To get a sense of these interactions, jump to the video demos at the 2:15 mark after the break.

If you’re curious to dig into the project’s inner workings, [chronopoulos] has kindly put the firmware, schematics, and layout files on Github with a generous MIT License. He’s even released a companion paper [PDF] that details the math behind detecting these gestures. And finally, if you just want to cut to the chase and make music of your own, you can actually snag this one on Tindie too.

MEMs sensors are living a great second life outside our phones these days, and this project is another testament to the richness they offer for new project ideas. For more MEMs-sensor-based projects, have a look at this self-balancing robot and magic wand.

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Scanning electron micrograph of a microfabricated lens array

Getting A Fly’s-Eye View With Microfabricated Lens Arrays

September 7, 2021 by 11 Comments

Atomic force microscopy, laser ablation, and etching with a witches brew of toxic chemicals: sounds like [Zachary Tong] has been playing in the lab again, and this time he found a way to fabricate arrays of microscopic lenses as a result.

Like many of the best projects, [Zach]’s journey into micro-fabrication started with a happy accident. It happened while he was working on metal-activated chemical etching (MACE), which uses a noble metal catalyst to selectively carve high-aspect-ratio features in silicon. After blasting at a silver-coated silicon wafer with a laser, he noticed the ablation pits were very smooth and uniform after etching. This led him to several hypotheses about what was going on, all of which he was able to test.

The experiments themselves are pretty interesting, but what’s really cool is that [Zach] realized the smooth hemispherical pits in the silicon could act as a mold for an array of microscopic convex lenses. He was able to deposit a small amount of clear silicone resin into the mold by spin-coating, and (eventually) transfer the microlens array to a glass slide. The lenses are impressively small — hundreds of them over only a couple hundred square microns — and pretty well-formed. There’s always room for improvement, of course, but for an initial attempt based on a serendipitous finding, we’d call it a win. As for what good these lenses are, your guess is as good as ours. But novel processes like these tend to find a way to be useful, and the fact that this is coming out of a home lab doesn’t change that fact.

We find this kind of micro-fabrication fascinating. Whether it’s making OLED displays, micro-machining glass with plasma, or even rolling your own semiconductors, we can’t get enough of this stuff.

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Hackaday Links: June 13, 2021

June 13, 2021 by 6 Comments

When someone offers to write you a check for $5 billion for your company, it seems like a good idea to take it. But in the world of corporate acquisitions and mergers, that’s not always the case, as Altium proved this week when they rebuffed a A$38.50 per share offer from Autodesk. Altium Ltd., the Australian company whose flagship Altium Designer suite is used by PCB and electronic designers around the world, said that the Autodesk offer “significantly undervalues” Altium, despite the fact that it represents a 42% premium of the company’s share price at the end of last week. Altium’s rejection doesn’t close the door on ha deal with Autodesk, or any other comers who present a better offer, which means that whatever happens, changes are likely in the EDA world soon.

There were reports this week of a massive explosion and fire at a Chinese polysilicon plant — sort of. A number of cell phone videos have popped up on YouTube and elsewhere that purport to show the dramatic events unfolding at a plant in Xinjiang province, with one trade publication for the photovoltaic industry reporting that it happened at the Hoshine Silicon “997 siloxane” packing facility. They further reported that the fire was brought under control after about ten hours of effort by firefighters, and that the cause is under investigation. The odd thing is that we can’t find a single mention of the incident in any of the mainstream media outlets, even five full days after it purportedly happened. We’d have figured the media would have been all over this, and linking it to the ongoing semiconductor shortage, perhaps erroneously since the damage appears to be limited to organic silicone production as opposed to metallic silicon. But the company does supply something like 17% of the world’s supply of silicon metal, so anything that could potentially disrupt that should be pretty big news.

It’s always fun to see “one of our own” take a project from idea to product, and we like to celebrate such successes when they come along. And so it was great to see the battery-free bicycle tire pressure sensor that Hackaday.io user CaptMcAllister has been working on make it to the crowdfunding stage. The sensor is dubbed the PSIcle, and it attaches directly to the valve stem on a bike tire. The 5-gram sensor has an NFC chip, a MEMS pressure sensor, and a loop antenna. The neat thing about this is the injection molding process, which basically pots the electronics in EDPM while leaving a cavity for the air to reach the sensor. The whole thing is powered by the NFC radio in a smartphone, so you just hold your phone up to the sensor to get a reading. Check out the Kickstarter for more details, and congratulations to CaptMcAllister!

We’re saddened to learn of the passing of Dale Heatherington last week. While the name might not ring a bell, the name of his business partner Dennis Hayes probably does, as together they founded Hayes Microcomputer Products, makers of the world’s first modems specifically for the personal computer market. Dale was the technical guru of the partnership, and it’s said that he’s the one who came up with the famous “AT-command set”. Heatherington only stayed with Hayes for seven years or so before taking his a $20 million share of the company and retiring, which of course meant more time and resources to devote to tinkering with everything from ham radio to battle bots. ATH0, Dale.

Macro Model Makes Atomic Force Microscopy Easier To Understand

June 12, 2021 by 6 Comments

For anyone that’s fiddled around with a magnifying glass, it’s pretty easy to understand how optical microscopes work. And as microscopes are just an elaboration on a simple hand lens, so too are electron microscopes an elaboration on the optical kind, with electrons and magnets standing in for light and lenses. But atomic force microscopes? Now those take a little effort to wrap your brain around.

Luckily for us, [Zachary Tong] over at the Breaking Taps YouTube channel recently got his hands on a remarkably compact atomic force microscope, which led to this video about how AFM works. Before diving into the commercial unit — but not before sharing some eye-candy shots of what it can do — [Zach] helpfully goes through AFM basics with what amounts to a macro version of the instrument.

His macro-AFM uses an old 3D-printer as an X-Y-Z gantry, with a probe head added to the printer’s extruder. The probe is simply a sharp stylus on the end of a springy armature, which is excited into up-and-down oscillation by a voice coil and a magnet. The probe rasters over a sample — he looked at his 3D-printed lattices — while bouncing up and down over the surface features. A current induced in the voice coil by the armature produces a signal that’s proportional to how far the probe traveled to reach the surface, allowing him to map the sample’s features.

The actual AFM does basically the same thing, albeit at a much finer scale. The probe is a MEMS device attached to — and dwarfed by — a piece of PCB. [Zach] used the device to image a range of samples, all of which revealed fascinating details about the nanoscale realm. The scans are beautiful, to be sure, but we really appreciated the clear and accessible explanation of AFM.

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Acoustic Camera Uses Many, Many Microphones

August 10, 2020 by 53 Comments

If you’re a human or other animal with two ears, you’ll probably find great utility in your ability to identify the direction of sounds in the world around you.  Of course, this is really just a minimal starting point for such abilities. When [John Duffy] set out to build his acoustic camera, he chose to use ninety-six microphones to get the job done.

The acoustic camera works by having an array of microphones laid out in a prescribed grid. By measuring the timing and phase differences of signals appearing at each microphone, it’s possible to determine the location of sound sources in front of the array. The more microphones, the better the data.

[John] goes into detail as to how the project was achieved on the project blog. Outlining such struggles as assembly issues, he also shares information about how to effectively debug the array, and just how to effectively work with so many microphones at once. Particularly impressive is the video of [John] using the device to track a sound to its source. This technology has potential applications in industry for determining the location of compressed air leaks, for example.

Overall, it’s a university research project done right, with a great writeup of the final results. [John]’s project would serve well as a jumping off point for anyone trying to build something similar. Phased array techniques work in RF, too, as this MIT project demonstrates. Video after the break.

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Fear Of Potato Chips: Samy Kamkar’s Side-Channel Attack Roundup

March 9, 2020 by 13 Comments

What do potato chips and lost car keys have in common? On the surface, it would seem not much, unless you somehow managed to lose your keys in a bag of chips, which would be embarrassing enough that you’d likely never speak of it. But there is a surprising link between the two, and Samy Kamkar makes the association in his newly published 2019 Superconference talk, which he called “FPGA Glitching and Side-Channel Attacks.”

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Wearable Cone Of Silence Protects You From Prying Ears

February 17, 2020 by 36 Comments

Careful,  the walls have ears. Or more specifically, the smart speaker on the table has ears, as does the phone in your pocket, the fitness band on your wrist, possibly the TV, the fridge, the toaster, and maybe even the toilet. Oh, and your car is listening to you too. Probably.

How does one fight this profusion of listening devices? Perhaps this wearable smart device audio jammer will do the trick. The idea is that the MEMS microphones that surround us are all vulnerable to jamming by ultrasonic waves, due to the fact that they have a non-linear response to ultrasonic signals. The upshot of that is when a MEMS hears ultrasound, it creates a broadband signal in the audible part of the spectrum. That creates a staticky noise that effectively drowns out any other sounds the microphone might be picking up.

By why a wearable? Granted, [Yuxin Chin] and colleagues from the University of Chicago have perhaps stretched the definition of that term a tad with their prototype, but it turns out that moving the jammer around does a better job of blocking sounds than a static jammer does. The bracelet jammer is studded with ultrasonic transducers that emit overlapping fields and result in zones of constructive and destructive interference; the wearer’s movements vary the location of the dead spots that result, improving jamming efficacy. Their paper (PDF link) goes into deeper detail, and a GitHub repository has everything you need to roll your own.

We saw something a bit like this before, but that build used white noise for masking, and was affixed to the smart speaker. We’re intrigued by a wearable, especially since they’ve shown it to be effective under clothing. And the effect of ultrasound on MEMS microphones is really interesting.

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