Air quality sensor SEN5x MH-Z19 SSD1327

Hello;

I would like to present my take on air quality sensor made out of:

• ESP32 board;
• SEN55 - PM/NOx/VOC sensor;
• MH-Z19 - CO2 sensor;
• SSD1327 - display;

Chassis will require :

Filaments

• Geetech marble PLA;
• FiberFlex 30D (TPE TPU);

Non-printable:

• 6x2 mm magnets - x8;
• 3 mm screws about 10 mm long - x5;
• 3 mm inserts - x5;
• “computer mesh” on Aliexpress;
• USB-C socket;
• parts mentioned at the beginning.

There are 3 parts and 3 seals:

• bottom - that has an additional wall compared to the middle one;
• middle - that holds all electrical components;
• top - that has no walls.

Assembly:

• place inserts and magnets - mind polarity;
• cut down one strip of mesh about 48mm x 450mm and push it into the bottom part;
  • It may require pulling it with something pointy from the other side between the honeycomb lattice - especially when going through corners;
  • If it covers honeycomb lattice from top to bottom You are good if not adjust second one and put better one an bottom. Trim excess part;
• Place biggest TPU seal between bottom and middle part;
• Screw them together;
• Place Your electronic components;
  • Display - bend upper arms outside push display down;
  • ESP just slides down;
  • MH - spread “gate” outside and place it down;
  • SEN :
    • place other TPU sealings;
    • place down SEN at angle that bottom part aligns with side brackets and top part sliced touching wall;
    • check if TPU sealings are on their place;
    • move top of SEN under securing arm;
• Attach upper part;

Notes:

• Top part holds on magnets for easier maintenance and access to esp32 usb port ICE;
• Bottom one is screwed together with the middle for sealing measures.

Specification of SEN requires isolating inlet and outlet channels and I was not able to make use off the shelf sealings such as rubber o-rings so in my opinion TPU is necessary.

I will pass on placing my particular ESPhome configuration :

- It is fairly easy to start running;

- DYOR and adjust configuration to your use case;

Print with non volatile materials PLA and TPU.

You can basically treat this as platform for your own air quality sensor with different sensors, since there is some room left.

Things to improve:

- It is tricky to screw bolts beneath SEN clamp and magnets;

- After thermal imaging I am sure that there is no significant heat creep but in Your use case you may consider adding a double wall inside the middle chamber.

Edit: after some time I have came to conclusion that if you have same setup as me temp. offsets should be:

MH-Z19 -1 (minus one degree)

SEN55 -2 (minus two degrees)

Mind that Your sensor size may vary, for example my SEN module was off ~1mm from what their 3D model was.

Support enforcers are placed.