Earth Day: Environmental Sensors

Before you attempt to solve a problem, you must first study the problem. If there’s a problem with the environment, you must therefore study the environment at a scale never seen before. For this year’s Hackaday Prize, there are a lot of projects that aim to do just that. Here are a few of them:

[Pure Engineering]’s C12666 Micro Spectrometer has applications ranging from detecting if fruit is ripe, telling you to put sunscreen on, to detecting oil spills. Like the title says, it’s based on the Hamamatsu C12666MA spectrometer, a very tiny MEMS spectrometer that can sort light by wavelength from 340 to 780nm.

The project is to build a proper breakout board for this spectrometer. The best technologies are enabling technologies, and we can’t wait to see all the cool stuff that’s made with this sensor.

[radu.motisan]’s portable environmental monitor isn’t just one sensor, but an entire suite of them. The design of the project includes toxic and flammable gas sensors, radiation detectors, dust sensors, and radiation detectors packaged together in a neat, convenient package.

[radu] has already seen some success with environmental sensors and The Hackaday Prize; last year, his entry, the uRADMonitor placed in the top fifty for creating a global network of radiation sensors.


Global Radiation Monitoring Network Update

Things have been busy at Global Radiation Monitoring Network Central Command. As a semifinalist in the Hackaday Prize, project creator [Radu Motisan] has quite a bit of work to do. He’s not slacking off either. With 33 project logs (and counting), [Radu] has been keeping us up to date with his monitoring network and progress on uRADMonitor , the actual monitoring hardware.

[Radu’s] latest news is that he’s ready to go into production with model A of the uRADMonitor. Moving from project to production can be an incredible amount of work due to sourcing parts, setting up assembly houses, and dealing with any snags that come up along the way. We’re sure [Radu] can handle it, though.

The network of uRADMonitors is also growing. A new monitor was just installed in Prescott, Arizona. This is the 10th unit in the USA.  You can view the map, data, and graphs of global radiation live on the uRADMonitor website.

SpaceWrencherThe project featured in this post is a semifinalist in The Hackaday Prize.

THP Hacker Bio: radu.motisan


Here’s a great example of thinking big while keeping it simple. [Radu Motisan‘s] putting together a global radiation monitoring network as his entry in The Hackaday Prize.

The simplicity comes in the silver box pictured above. This houses the Geiger tube which measures radiation levels. The box does three things: hangs on a wall somewhere, plugs into Ethernet and power, and reports measurements so that the data can be combined with info from all other functioning units.

After seeing the idea we wanted to know more about [Radu]. His answers to our slate of queries are found below.

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Improving A Homebrew CT Scanner With Barium


[Peter] has been working on his homebrew CT scanner for a while, and it’s finally become something more than a spinning torus of plywood. He’s managed to image the inside of a few pieces of produce using an off-the-shelf radiation detector and a radioactive barium source

When we last saw [Peter]’s CT scanner, he had finished the mechanical and electronic part of the Stargate-like device, but the radioactive source was still out of reach. He had initially planned on using either cadmium 109 or barium 133. Both of these presented a few problems for the CT scanner.

The sensor [Peter] is a silicon photodiode high energy particle detector from Radiation Watch this detector was calibrated for cesium with a detection threshold of around 80keV. This just wasn’t sensitive enough to detect 22keV emissions from Cd109, but a small add-on board to the sensor can recalibrate the threshold of the sensor down to the noise floor.

Still, cadmium 109 just wasn’t giving [Peter] the results he wanted, resulting in a switch to barium 133. This was a much hotter source (but still negligible in the grand scheme of radioactivity) that allowed for a much better signal to noise ratio and shorter scans.

With a good source, [Peter] started to acquire some data on the internals of some fruit around his house. It’s still a slow process with very low resolution – the avocado in the pic above has 5mm resolution with an acquisition time of over an hour – but the whole thing works, imaging the internal structure of a bell pepper surprisingly well.

Turning a phone into a Geiger counter


We’re no stranger to radiation detector builds, but [Dmytry]’s MicroGeiger prototype is one of the smallest and most useful we’ve seen.

The idea behind the MicroGeiger comes from the observation that just about every modern smartphone can provide a small bit of power through the microphone jack. Usually this is used for a microphone, but with the right circuit it can be stepped up enough to power a Geiger tube.

[Dmytry]’s circuit uses a hand-wound transformer but keeps the part count low; there’s only a few dozen caps, resistors, and diodes in this build, making the circuit much smaller than the Geiger tube itself.

Since [Dmytry] is powering a Geiger tube with a phone, it only makes sense that he should also record clicks from the tube with an Android app. Right now, the entire project is still in the prototype stage, but everything works and his app can detect radiation from one of [Dmytry]’s sources.

The code and schematics for the MicroGeiger are available on GitHub, with a video of the project in action below.

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A very tiny gamma ray detector


When you think of a radiation detector, you’re probably thinking of a Geiger tube and its high voltage circuitry. That isn’t the only way to measure gamma radiation, though, and [Alan] has a great circuit to measure even relatively weak radiation sources. It uses a very small photodiode, and draws so little power it’s perfect for projects with the smallest power budgets.

The detector circuit uses a miniature solar cell and a JFET wired up in a small brass tube to block most of the light and to offer some EM shielding. This, in turn, is attached to a small amplifier circuit with a LED, Piezo clicker, and in [Alan]’s case a small counter module. The photodiode is actually sensitive enough to detect the small amounts of gamma radiation produced from a smoke alarm americium source, and also registers [Alan]’s other more powerful radioactive sources.

The circuit only draws about 1mA, but [Alan] says he can probably get that down to a few micoAmps. A perfect radiation sensor for lightweight and low power applications, and gives us the inspiration to put a high altitude balloon project together.

Online radiation monitoring station


This is a Geiger counter which charts its readings on a webpage. [Radu Motisan] put a lot of time into the build and it shows. This thing is packed with features and the hardware choices were the best combinations found through several iterations of development.

In addition to radiation levels the sensor unit takes several other measurements. These include temperature, humidity, luminosity, and barometric pressure. All of the sensor data is monitored and gathered by an ATmega168 which can be charted on a webpage with the help of an ENC28J60 Ethernet chip. The collection and display of this data is detailed at the post linked above.

For those interested in the hardware development, [Radu] published many updates along the way. These are available in his forums posts, as well as his build log. He doesn’t have any videos of his recent work, but way back in May he did publish a clip (found after the break) which shows the testing of different Geiger tubes.

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