Hacker-Friendly And Elegant Air Quality Sensor Hub

The sensor hub in all its glory, sensor itself on top, standing on 3D-printed feet, and the PCB on the bottom

Ever wanted an indoor environment sensor that’s dead simple yet a complete package? That’s the anotter-sensor-hub project from [Jana Marie], designed for the Sensirion SEN05x series sensors, with a SEN055 sensor shown in the picture above. Given such a sensor, you can measure VOCs and NOCs (Volatile and Non-Volatile Organic Compounds), as well as PM1, PM2.5, PM4 and PM10 particulate matter indices, with temperature and humidity sensing thrown in for good measure. Fully open and coupled with 3D printable stand files, this alone makes for an air quality hub fit for a hacker’s desk. That’s not all, however — this board’s elegant extensibility is a good match for the sensor’s impressive capabilities!

The PCB itself might look simple, it’s simply an ESP32 and some supporting circuitry required. But you’ll notice there’s also a trove of connector footprints for different interfaces; whatever else you might want to add to your sensor hub, whether it connects through I2C, SPI or PWM, you can! As usual, the sensor itself is the most expensive part of such a project — the boards themselves are around $5 USD apiece fully assembled, but one sensor-included hub will set you back roughly $42 USD. That said, it’s a great value for the price, and the trove of sensing data you can get might just more than pay for itself in quality-of-life improvements you make. Of course, everything is open-source and comes as a complete packages for you to start using. The firmware, KiCad files, 3D holder and even Grafana dashboard files can be found on GitHub.

Such air quality sensor platforms have been getting more and more popular, and hackers have been paying attention. Having a full open-source package like this at our disposal is amazing. If you’re looking for a cheaper “baby’s first air quality sensor”, drop by your local IKEA — there’s a way less featureful but quite cheap sensor that you can equip with an ESP8266, perhaps, even on a custom PCB.

9 thoughts on “Hacker-Friendly And Elegant Air Quality Sensor Hub

  1. wow: I have friends about to have a baby, so I’m going to try to make this as a baby-warming gift… it’s a bit on the edge of anything I’ve done, I may be back with questions! Thanks, this is awesome! There are several things here on my “get familiar with that” list, like ESP32, and I’d never seen Grafana which seems fantastic. Great stuff!

  2. I just ordered the PC board and the sensors (5 boards and 2 sensors). The boards were nothing but shipping, I added an “expensive” stencil for $7. Shipping was pricey. I ordered the two SEN55 from Digikey for $70. I’m not sure how quickly I’ll get to the project, but part of it is to as a baby shower present, and the baby probably won’t be slowing down for me to finish…

  3. Hey cool project,

    I did something similar back in college but I encountered the problem, that the 3d printed parts emitted “stuff” which interfered with the voc sensors and made them basically useless for a week or two. I put the module in a closed case with air inlets instead of stands only.
    Probably that’s the trick…
    Which material did you use to print the stands?

    As a side note, the “predecessor” of this sensor module is inside of amazon’s own air quality monitor. So you can probably use this thing as a performance reference if you need any.

  4. Hello [Janna] – After reading about your Sensor Hub on Hackaday I bought an SEN55 from Mouser for testing. It arrived in two days (domestic U.S. FedEx 2nd day). Question: What connector and pins are you using to connect the Sensirion SEN55 sensor to your Sensor Hub board. Actually at a minimum I’m interest in the connector and pins for just the cable that goes from the sensor-side to some simple broken-out pig-tails.

    * I think the correct cable-side connector is this:

    JST Mfgr P/N GHR-06V-S Desc CONN RCPT HSG 6POS 1.25MM $0.19 each 25,291 In Stock


    * And the correct cable-side mating pin is this:

    JST Mfgr P/N SSHL-002T-P0.2 Desc CONN SOCKET 26-30AWG CRIMP TIN $0.11 each 0 In Stock


    The problem is the pins for the connector are ZERO STOCK everywhere in small quantity with immediate delivery. Everywhere I looked (Yes, I tried findchips, octopart, etc.) is no stock. Connectors without mating pins are useless.

    So now I have the SEN55 sensor, but for lack of a good source of the mating connector – I can do NOTHING with it. If Sensirion sent the sensor with an example cable and connector, or sold a cable assembly separate with some flying leads, it would really help them sell more modules. But nope, that would make sense.

    I have presented this problem to both Digi-Key and Mouser asking for help. Digi-Key ignored my Email. On the phone, Mouser said they will not do anything to help… It seems I’m on my own. Yes, there’s a lot more I can do to dig into this problem online. But I thought maybe you just have the part number for what worked for you handy. I do not see a BOM on your GitHub repository.

    Thank You, David

      1. Thank you [Jana] for your recommendation. Indeed the pre-crimped assembly you suggested looks ideal except for one thing – getting it shipped from the EU to the USA. Apparently these small JST GH/GHR connector assemblies are quite popular in the EU – but not so much in the USA.

        I did manage to find the exact connector shell and pins specified by Sensirion at one US distributor called Newark (an AVNET Company) but yeah, like I have found everywhere else if you can get the connector pins in the USA in the first place, they are outrageously expensive:

        1. Qty-2, JST P/N: GHR-06V-S, Newark P/No: 74M2124, $0.186 ea., $0.372 ext.


        2. Qty-16, JST P/No: MINI-SSHL-002T-P0.2, Newark P/No: 4M3274, $0.385 ea., $6.16 ext.


        So I just gave up and over-paid for the items above. Shipping was an additional $10 or so in the domestic U.S.

        I did manage to find what looks like a set of 6-pin JST GH housings and pins on Amazon, but it is a roll of the dice whether they will work in the end. The price is good though, and shipping is tolerable at around a week. See here:

        3. CQRobot 100 Sets/800 Pieces JST GH 1.25mm Pitch 6 Pin JST Connector Kit. JST 1.25mm Pitch Terminals, JST GH 6 Pin Housing JST Adapter Cable Connector Socket Male and Female, Crimp DIP Pins kit. Brand: CQRobot 4.6 out of 5 stars 1,511 ratings #1 Best Seller in IC Sockets & Plugs $12.39


        No matter how you look at it, for me in the USA this mating connector for the Sensirion SEN55 module remains a big obstacle to painless-affordable adoption of the product.

        For anyone else interested, I usually use this relative inexpensive crimper tool, but I have not tried it yet with these elusive GH/GHR connector pins. Time will tell though as I have some GH/GHR housing parts and pins on the way. I like this crimp tool because it does only one crimp at a time and does not have a ratchet.

        4. iCrimp Mini Micro Open Barrel Crimping Tools Works on AWG28-20 JAM, Molex, Tyco, JST Terminals and Connectors used for FPV, Drone Servo 4.5 out of 5 stars 1,203 ratings Amazon’s Choice for “jst crimper” $19.99


        As my frustrating adventure with this connector continues, I’ll post back here from time to time with (hopefully) good news.

        Best Regards, David

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