Leafi a Leaf-shaped Air Quality Sensor

A Leaf But Smarter

Leafi is a leaf-shaped air quality sensor designed to raise awareness about indoor pollution in a fun and educational way. Powered by an MQ135 sensor and a WS2812B LED strip, Leafi visualizes air quality in real time by transitioning from green to red—green when the air is clean, red when it's polluted. It also features multiple lighting modes, including ambient animations and a relaxing "lounge mode", with adjustable brightness to match any atmosphere. Fully open-source and 3D-printed, Leafi is eco-friendly, customizable, and perfect for makers, educators, and anyone who wants to make the invisible visible.

Electronics:

1. 1X MQ-135 Sensor https://tinyurl.com/yc4zb3pc
2. 1X Arduino nano https://tinyurl.com/2wdw9s6p
3. 1X Female USB-C Connector https://tinyurl.com/54vz655f
4. 1X 330Ω resistor https://tinyurl.com/2fp34p7y
5. 1X Male USB-C connector https://tinyurl.com/tsd4apfx
6. WS2812B 5V Led strip (144 Leds/m) https://tinyurl.com/56exza8c
7. 1X 6×6 momentary push button https://tinyurl.com/yxjv8f8m
8. 1X 5v USB-C Power supply

Tools:

1. Soldering iron & solder
2. Hot glue gun or epoxy or cyanoacrylate glue
3. 2X M3 and 2X M1 screws (or just more glue)
4. Wire cutter/stripper
5. Optional: translucent filament for the leaf (for best glow)
6. Jumper cables

3D-Printed Parts:

1. LEAFI_BODY
2. LEAFI_BOTTOM_CAP
3. LEAFI_BOTTOM
4. LEAFI_BUTTON
5. 2X LEAFI_LEAF-BICOLOR
6. LEAFI_SWITCH_HOLDER
7. LEAFI_TUBE

All parts can be printed in PLA

**You can also download my full instructions pdf file :)**

RGB vibes for eco-nerds 🌈🍃

No screws required for the printed parts– it's all snap-fit

Female USB-C connector is glued to LEAFI_BOTTOM.stl

🔘 Installing the Button

Insert the LEAFI_BOTTON.stl in the hole, then place the 6×6 mm momentary push button on top of the LEAFI_BUTTON.stl. Then, carefully place the LEAFI_SWITCH_HOLDER.stl on top to hold it in place.

⚠️ It might take a bit of gentle persuasion — don’t worry, Leafi won’t bite! 😄

Once everything is aligned, I recommend adding a small dab of glue to keep the button nice and snug.

Now your Leafi is ready to click and glow! 🌟

Components connected to Arduino Nano

MQ135 Sensor

VCC → 5V

GND → GND

AOUT → A0

WS2812B LED Strip (61 LEDs)

DIN → 330OHM RESISTOR →D6

+5V → 5V

GND → GND

Switch Button (6×6mm)

One leg → D2

Other leg → GND

And plug the male usb-c to the arduino and connect it to the female usb-c plug

The Arduino Nano and the MQ135 sensor can be mounted using M3 and M1 screws, but you can also glue them in place instead of screwing.

Upload the code to the arduino nano !

Power

🔌 Plug Leafi into a 5V USB-C power source.

Modes

Leafi features 4 lighting modes:

1. MEASURE – Color changes based on air quality
2. LOUNGE – Ambient color animation
3. SPOT – Static light for focused use
4. WAVE – Slow, flowing color transitions

🕹️ Hold the button to switch between modes.

Brightness

💡 Short press the button to cycle through brightness levels.

Enjoy the glow!