SDS011 Sensor + USB Serial Cable
Available on AliExpress (subject to change; always search "SDS011 sensor" for latest price and availability).
Price and link may vary over time.
Open hardware · CC0
A DIY air quality sensor for your phone
Aqui is an air quality sensor that connects to a phone and shows the real-time PM2.5 and PM10 particulate readings. By leaning on your phone’s processor, battery, and connectivity, Aqui itself stays radically minimal, efficient, and frugal.
Aqui is an open-source DIY electronics project, released under the Creative Commons CC0 dedication. The parts can be ordered from AliExpress or other electronics suppliers, and the enclosure can be 3D printed.
Assembled units
If you want to buy a few assembled units, contact ayushpatnaik@gmail.com (Rs. 4000 per piece). We recommend building it yourself for the best learning and value.
Version 1.1
Companion app
The Aqui Android companion app is open‑source on GitHub. It connects to the sensor over USB serial and streams the live particulate data (PM2.5 / PM10) to your phone.
- New look. PM2.5 as one large number, with its air quality category and PM10 below.
- New icon. The coral Aq tile, with 2.5 in the corner.
- Steadier connection. More reliable connecting and disconnecting when the sensor is plugged in or pulled out.
Android asks you to allow installs from your browser the first time. Play Store listing coming soon.
Special thanks to Saurabh Nandedkar for help building the app.
DIY build guide
Build your own Aqui
Three parts: the sensor with its USB serial cable, an OTG cable for your phone, and a 3D printed case.
USB Type C to USB 3.0 OTG Cable
Required to connect the sensor to most modern Android phones. Available on AliExpress, Amazon, or local electronics stores.
3D Printed Case
Print the enclosure using the STL or STEP files on any standard FDM 3D printer with PLA/ABS filament. A local shop can print it for around Rs. 400. If you are in Delhi, Shaperjet is highly recommended for quality prints.
- You will also need a few small screws (M2), a screwdriver, and some tape or double-sided tape for assembly and securing the parts.
- Follow the assembly video and use the companion app to get real-time air quality readings on your phone.
Videos
See Aqui working in the real world and learn how to assemble your own unit. These short clips demonstrate particulate spikes and the full build process.
Aqui in action
Live demonstration of how PM2.5 / PM10 readings respond when incense (agarbatti) is lit near the intake.
Assembly tutorial
Step-by-step walkthrough of sourcing parts, 3D printed case, and final assembly using the SDS011 sensor.
Sensor details
The SDS011 is a laser-based sensor that measures PM2.5 and PM10 particulate matter concentrations in the air. It uses a small fan to draw air in and a laser to detect particles. The sensor provides reliable, real-time data.
Data is transmitted from the sensor using the UART protocol, which allows it to be easily read by a microcontroller or other devices.
An experiment by aqicn.org shows the sensor is very accurate. It is suited for our use case i.e. intermittent air quality monitoring.
3D printed case
Preview the printable enclosure parts directly in your browser, and drag a preview to turn it. Download the STL files for the top and base. A STEP file is provided if you want to remix or adapt the design (optional).
3D preview
Top shell
Download STL3D preview
Base
Download STL.STEP is a neutral CAD exchange format that preserves precise parametric geometry (not just a triangle mesh). Use it to modify or remix the enclosure in a CAD program, then export an STL for printing.
Full assembly (STEP, optional)
Download STEPContribute
Aqui is an open-source project and we welcome contributions. Here are a few ways you can help:
01
Financial support
Support Aqui financially to help us assemble more devices. We will donate these to students or researchers who can benefit from air quality monitoring.
02
Logo & branding
If you have graphic design skills, help us create a logo or other branding assets for Aqui. Visual identity makes the project more recognizable and inviting.
03
Android development
If you're an Android developer, you can help improve the companion app. There are always new features to add and bugs to fix.
04
Case design
If you have experience with 3D modeling and printing, you can help improve the case design to make it more robust, easier to print, or more aesthetically pleasing.
05
Assembly & manufacturing
If you're interested in manufacturing and assembly, you can help streamline the process of building Aqui devices, making it easier for others to build their own.
Any other help is also welcome. The ultimate objective of this project is to bring awareness about air quality. If you have ideas or skills that could help, please reach out to ayushpatnaik@gmail.com.