New Part Day : A Sensor Chip For 3D Color X-Ray Imaging

February 14, 2019 by Anool Mahidharia 19 Comments

We all know CERN as that cool place where physicists play with massive, superconducting rings to smash atoms and subatomic particles to uncover secrets of matter in the Universe. To achieve this aim, they need to do a ton of research in other areas, such as development of special particle detectors.

While such developments are essential to the core research needs of the Centre, they also lead to spinoff applications for the benefit of society at large. One such outcome has been the Medipix Collaborations – a family of read-out chips for particle imaging and detection that can count single photons, allowing X-rays and gamma rays to be converted to electrical signals. It may not be possible for us hackers to get our hands on these esoteric sensors, but these devices are pretty interesting and deserve a closer look. Medipix sensors work like a camera, detecting and counting each individual particle hitting the pixels when its electronic shutter is open. This enables high-resolution, high-contrast, noise hit free images – making it unique for imaging applications.

Some months back, CERN announced the first 3D color X-ray of a human made possible using the Medipix devices. The result is a high-resolution, 3D, color image of not just living structures like bones, muscular tissues and vessels, but metal objects too like the wrist watch, seen in the accompanying photograph. The Medipix sensors have been in development since the 1990’s and are presently in their 4th “generation”. Each chip consists of a top semiconducting sensor array, made from gallium arsenide or cadmium telluride. The charge collected by each pixel is transported to the CMOS ASIC electronics via “bump bonds”. The integration is vertical, with each sensing pixel connected via the bump bond to an analog section followed by a digital processing layer. Earlier versions were limited, by technology, in their tiling ability for creating larger matrices of multiple sensors. They could be abutted on three sides only, with the fourth being used for on-chip peripheral logic and wire-bond pads that permit electronic read-out. The latest Medipix4 Collaboration, still under some development, eliminates this short coming. Through-silicon-via (TSV) technology provides the possibility of reading the chips through copper-filled holes that bring the signals from the front side of the chip to its rear. All communication with the pixel matrix flows through the rear of the chip – the peripheral logic and control elements are integrated inside the pixel matrix.

The Analog front end consists of a pre-amplifier followed by a window discriminator which has upper and lower threshold levels. The discriminator has four bits for threshold adjustment as well as polarity sensing. This allows the capture window to be precisely set. The rest of the digital electronics – multiplexers, shift registers, shutter and logic control – helps extract the data.

Further development of the Medipix (Tech Brief, PDF) devices led to a separate version called Timepix (Tech Brief, PDF). These new devices, besides being able to count photons, are capable of two additional modes. The first mode records “Time-Over-Threshold”, providing rough analog information about the energy of the photon. It does this by counting clock pulses for the duration when the signal stays above the discrimination levels. The other mode, “Time of Arrival”, measures arrival time of the first particle to impinge on the pixel. The counters record time between a trigger and detection of radiation quanta with energy above the discrimination level, allowing time-of-flight applications in imaging.

Besides medical imaging, the devices have applications in space, material analysis, education and of course, high energy physics. Hopefully, in a few years, hackers will lay their hands on these interesting devices and we can get to know them better. At the moment, the Medipix website has some more details and data sheets if you would like to dig deeper. For an overview on the development of such single photon detectors, check out this presentation from CERN – “Single X-Ray Photon Counting Systems: Existing Systems, Systems Under Development And Future Trends” (PDF).

Create An Aurora Of Your Own

February 2, 2019 by Bryan Cockfield 14 Comments

Throughout our day-to-day experiences, we come across or make use of many scientific principles which we might not be aware of, even if we immediately recognize them when they’re described. One such curiosity is that of caustics, which refers not only to corrosive substances, but can also refer to a behavior of light that can be observed when it passes through transparent objects. Holding up a glass to a light source will produce the effect, for example, and while this is certainly interesting, there are also ways of manipulating these patterns using lasers, which makes an aurora-like effect.

The first part of this project is finding a light source. LEDs proved to be too broad for good resolution, so [Neuromodulator] pulled the lasers out of some DVD drives for point sources. From there, the surface of the water he was using to generate the caustic patterns needed to be agitated, as the patterns don’t form when passing through a smooth surface. For this he used a small speaker and driver circuit which allows precise control of the ripples on the water.

The final part of the project was fixing the lasers to a special lens scavenged from a projector, and hooking everything up to the driver circuit for the lasers. From there, the caustic patterns can be produced and controlled, although [Neuromodulator] notes that the effects that this device has on film are quite different from the way the human eye and brain perceive them in real life. If you’re fascinated by the effect, even through the lens of the camera, there are other light-based art installations that might catch your eye as well.

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Particle Paves Way For LTE Selfies

January 15, 2019 by Tom Nardi 3 Comments

From cars to refrigerators, it seems as if every new piece of tech is connected to the Internet. For better or for worse, we’re deep into the “Internet of Things”. But what about your camera? No, not the camera in your smartphone; that one’s already connected to the Internet and selling your secrets to the highest bidder. Don’t you think your trusty DSLR could be improved by an infusion of Wide Area Networking?

Regardless of what you’re answer to that question might be, [Thomas Kittredge] decided his life would be improved by making his beloved Canon EOS Rebel T6 an honorary member of the Internet of Things. Truth be told he says that he hasn’t quite figured out an application for this project. But since he was looking to mess around with both the LTE-enabled Particle Boron development board and designing his own PCB for professional production, this seemed a good a way to get his feet wet as any.

The resulting board is a fairly simple “shield” for the Particle Boron that let’s [Thomas] trigger up to two cameras remotely over the Internet or locally with Bluetooth. If LTE isn’t your sort of thing though, don’t worry. Since the Boron follows the Adafruit Feather specification, there’s a whole collection of development boards with various connectivity options that this little add-on can be used with.

In the GitHub repository, [Thomas] has put up the files for the PCB, the STLs for the 3D printed enclosure, and of course the firmware source code to load onto the Particle board. He currently has code to expose the two shutter triggers as functions the the Particle Cloud API, as well as a practical example that fires off the camera when specific words are used in a Slack channel.

Out for a little over a year, the Particle Boron is a fairly new addition to the world of cellular development boards. Historically we haven’t seen a whole lot of cellular capable projects, likely because it’s been such a hassle to get them online, but with new boards like the Boron we might start seeing an uptick in the random pieces of gear that have this form connectivity and an internet-facing IP address. Surely nothing bad could come of this!

Photon Door Lock Swaps Keys For A POST Request

September 7, 2018 by Tom Nardi 18 Comments

At this point we’re all well aware of the fact that there is some inherent danger involved when bringing “things” onto the Internet. Nobody wants to come home to a smoldering pile of ruble because their Internet connected toaster oven decided to get stuck on “Hades.” But even with the risks, occasionally we see projects that prove at least some intrepid hackers are managing to navigate the Internet of Things to solve real-world problems.

[Daniel Andrade] writes in to tell us about the Internet controlled entry system he’s setup at his new apartment, and while we imagine it’s not for everyone, we can’t deny it seems like it has improved his quality of life. Rather than giving all of his friends a copy of his key, he’s setup a system where anyone who has the appropriate link can “buzz” themselves in through the building’s existing intercom system.

Thanks to the old-school intercom setup, the hardware for this project is simple in the extreme. All [Daniel] needed was a relay to close the circuit on the door buzzer, and a way to fire it off. For his controller he chose the Photon from Particle, which is perhaps a bit overkill, but we all tend to work with what we’re personally comfortable with.

Most of the work went into the software, as [Daniel] ended up coming with two distinct ways to control the door lock over the Internet. The first method uses Blynk, which allows you to create slick visual interfaces for mobile devices. His second version is controlled with a POST request to a specific URL, which he likes because it gives him more flexibility as to how he can interact with the lock. Currently he has a simple web page setup that lets friends and family open the door by just clicking a button.

We’ve seen a similar setup using the Photon to open a garage door, and plenty of people have taken to using Blynk to control their home automation setups. All the tools are available for you to roll your own IoT gadgets, you just need to figure out what to do with the things…

The Internet Of Three-Pointers

March 30, 2018 by James Hobson 1 Comment

When tossing something into the rubbish bin, do you ever concoct that momentary mental scenario where you’re on a basketball court charging the net — the game’s final seconds ticking down on the clock — making a desperate stretch and flicking some crumpled paper perfectly into the basket only for no one to notice your awesome skills? Well, now you can show off how good you are at throwing out garbage.

Well, not strictly garbage. The genesis of this IoT basketball hoop was in fact an inflatable ball on [Brandon Rice]’s desk that he felt would be more fun to fidget with if he could keep score. The hoop and backboard were laser cut on his Epilog cutter, and sport a Particle Photon to track and upload his running point tally to the Internet. An Arduino and IR sensor detect objects passing through the hoop — ultrasound proved to be too slow to keep up with [Rice]’s shots.

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We Are Now At DEFCON 2

September 16, 2017 by James Hobson 18 Comments

If you had a working DEFCON meter that reported on real data, would it be cool or distressing?

Before we get ahead of ourselves: no, not that DEF CON. Instructables user [ArthurGuy] is a fan of the 1983 movie War Games, and following a recent viewing –hacker senses a-tingling — he set to work building his own real-time display.

Making use of some spare wood, [ArthurGuy] glued and nailed together a 10x10x50cm box for the sign. Having been painted white already at some point, the paint brilliantly acted as a reflector for the lights inside each section. The five DEF CON level panels were cut from 3mm pieces of coloured acrylic with the numbers slapped on after a bit of work from a vinyl cutter.

Deviating from a proper, screen-accurate replica, [ArthurGuy] cheated a little and used WS2812 NeoPixel LED strips — 12 per level — and used a Particle Photon to control them. A quick bit of code polls the MI5 terrorism RSS feed and displays its current level — sadly, it’s currently at DEFCON 2.

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3D Printed Mini-Printer Enables Obsession With Lists

January 1, 2017 by James Hobson 8 Comments

When going about a busy day, a hard copy listing all your tasks helps if you aren’t inclined to pull up a notepad — or whatever app you use — on your phone each time; doubly so if you want to pin it up in one place to refer to. Besides, using a full sheet of paper for a few items is impractical — and wasteful. To that end, [Jed Hodson] has concocted a mini printer for all your listing needs.

[Hodson] designed and 3D printed the case, making the files available for download and instructions on how to assemble it. Being an IoT device, the printer uses a Photon board to connect to the Internet, wherein Microsoft Flow is used to liaise between the Adafruit printer and Wunderlist — the list app [Hodson]’s chosen for this project.

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