Hacking The ZH03B Laser Particle Sensor

Laser particle detectors are a high-tech way for quantifying whats floating around in the air. With a fan, a laser, and a sensitive photodetector, they can measure smoke and other particulates in real-time. Surprisingly, they are also fairly cheap, going for less than $20 USD on some import sites. They just need a bit of encouragement to do our bidding.

[Dave Thompson] picked up a ZH03B recently and wanted to get it working with his favorite sensor platform, Mycodo. With a sprinkling of hardware and software, he was able to get these cheap laser particle sensors working on his Raspberry Pi, and his work was ultimately incorporated upstream into Mycodo. Truly living the open source dream.

The ZH03B has PWM and UART output modes, but [Dave] focused his attention on UART. With the addition of a CP2102 USB-UART adapter, he was able to connect it to his Pi and Mac, but still needed to figure out what it was saying. He eventually came up with some Python code that lets you use the sensor both as part of a larger network or service like Mycodo and as a stand-alone device.

His basic Python script (currently only tested on Linux and OS X), loops continuously and gives a running output of the PM1, PM2.5, and PM10 measurements. These correspond to particles with a diameter of 1, 2.5, and 10 micrometers respectively. If you want to plug the sensor into another service, the Python library is a bit more mature and lets you do things like turn off the ZH03B’s fan to save power.

These sensors are getting cheap enough that you can build distributed networks of them, a big breakthrough for crowd-sourced environmental monitoring; especially with hackers writing open source code to support them.

Kill the Exhaust, Not Your Lungs with the Fume Coffin

As if slinging around 40 watts of potentially tattoo-removing or retina-singeing laser beams wasn’t anxiety-inducing enough, now comes a new, scary acronym – LCAGs, or “laser-generated airborne contaminants.” With something that scary floating around your shop, it might be a good idea to build a souped-up laser cutter exhaust fan to save your lungs.

We jest, but taking care of yourself is the responsible way to have a long and fruitful hacking career, and while [patternmusic]’s “Fume Coffin” might seem like overkill, can you go too far to protect your lungs? Plywood and acrylic, the most common materials that come across a laser cutter’s bed, both release quite a witch’s brew of toxins when vaporized by a laser beam. The Fume Coffin clears the air in your shop by venting it to the outdoors after giving it a good scrubbing through an activated charcoal pre-filter and a HEPA polishing element. Both filters are commercially available so replacements won’t be an issue, and the entire thing is housed in a wooden box that gives the device its name.

Since it’s ejecting 200 cubic feet per minute, you’ll have to provide at least that much make-up air, but other than that the Fume Coffin should be a welcome addition to the shop. We’ve seen a few other attempts to handle LCAGs effectively before, including a DIY charcoal and automotive air filter design.

A Portable, Accurate, Low-Cost, Open Source Air Particle Counter

If you live in a city with poor air quality you may be aware that particulates are one of the chief contributors to the problem. Tiny particles of soot from combustion, less than 10μm across, hence commonly referred to as PM10. These are hazardous because they can accumulate deep in the lungs, wherein all kinds of nasties can be caused.

There are commercial sensors available to detect and quantify these particles, but they are neither inexpensive nor open source. [Rundong] tells us about a project that aims to change that situation, the MyPart, which is described as a portable, accurate, low-cost, open source air particle counter. There is a GitHub repository for the project as well as a series of Instructables covering the build in detail. It comes from a team of members of the Hybrid Ecologies Lab at UC Berkeley, USA.

Along the way, they provide a fascinating description of how a particulate sensor works. A laser shines at right angles across a photodiode, and is brought to a focal point above it. Any particulates in the air will scatter light in the direction of the photodiode, which can thus detect them. The design of a successful such sensor requires a completely light-proof chamber carefully built to ensure a laminar flow of air past laser and diode. To that end, their chamber has several layers and is machined rather than 3D-printed for internal smoothness.

We’ve covered quite a few environmental sensors over the years here at Hackaday. An open source volatile organic compound (VOC) detector featured last year for example, or this Raspberry Pi-based  system using a commercial gas sensor.

Watch those VOCs! Open Source Air Quality Monitor

Ever consider monitoring the air quality of your home? With the cost of sensors coming way down, it’s becoming easier and easier to build devices to monitor pretty much anything and everything. [AirBoxLab] just released open-source designs of an all-in-one indoor air quality monitor, and it looks pretty fantastic.

Capable of monitoring Volatile Organic Compounds (VOCs), basic particulate matter, carbon dioxide, temperature and humidity, it takes care of the basic metrics to measure the air quality of a room.

Exploded CAD View

All of the files you’ll need are shared freely on their GitHub, including their CAD — but what’s really awesome is reading back through their blog on the design and manufacturing process as they took this from an idea to a full fledged open-source device.

Did we mention you can add your own sensors quite easily? Extra ports for both I2C and analog sensors are available, making it a rather attractive expandable home sensor hub.

To keep the costs down on their kits, [AirBoxLab] relied heavily on laser cutting as a form of rapid manufacturing without the need for expensive tooling. The team also used some 3D printed parts. Looking at the finished device, we have to say, we’re impressed. It would look at home next to a Nest or Amazon Echo. Alternatively if you want to mess around with individual sensors and a Raspberry Pi by yourself, you could always make one of these instead.