Introduction
Introduction
The bcMeter is an open-source optical absorption photometer designed to measure Black Carbon (BC) aerosols — commonly known as soot — in real-time. Whether you are monitoring ambient air quality in your neighborhood or measuring direct emissions from wood stoves, this device provides scientific-grade data at a fraction of the cost of reference instruments.
The device operates "headless" — it has no built-in screen. Instead, it hosts its own website that you can access from any smartphone or computer connected to the same network.
Hardware Variants
The bcMeter is available in two hardware variants:
| Variant | Platform | Status | Source |
|---|---|---|---|
| bcMeter (current) | ESP32-S3 | Production | Closed source (CC BY-NC 4.0) |
| bcMeter-dev | Raspberry Pi / Linux | Reference implementation | Open source |
Both variants run the same web interface and provide the same measurement capabilities. This documentation applies to both — differences are noted where relevant.
Device Types
- bcMeter — Portable aethalometer for ambient Black Carbon measurement. Designed for stationary or mobile deployment in monitoring networks, citizen science projects, and field campaigns.
- eBcMeter — Emission measurement instrument for direct source sampling from wood-burning stoves and similar combustion sources. Uses microgram (µg) units instead of nanogram (ng).
How Does It Work?
- Polluted air is drawn through filter paper by a pump
- The filter paper absorbs black carbon (BC) particles
- An LED shining at 880 nm passes through the filter; a sensor measures the attenuation (reduction in light intensity)
- A separate reference channel monitors the same LED through a clean portion of the filter, compensating for environmental changes
- The attenuation is converted to BC concentration (ng/m³) using Beer-Lambert law
- Data is saved as CSV and displayed in real-time on the web interface
Multi-wavelength: Optional 520 nm and 370 nm channels enable source apportionment via the Ångström Exponent (AAE) — distinguishing between fossil fuel and biomass burning sources.
Sensors & Capabilities
| Measurement | Sensor / Method | Notes |
|---|---|---|
| Black Carbon (BC) | Optical absorption at 880 nm | Primary measurement |
| Source apportionment | 520 nm, 370 nm (optional) | Ångström Exponent |
| Temperature | BME280 / SHT4x | Internal device temperature |
| Humidity | BME280 / SHT4x | |
| Pressure | BME280 | Barometric altitude |
| PM2.5 / PM10 | Sensirion SPS30 (optional) | |
| Airflow | Omron D6F differential pressure | Pump flow rate |
| GPS | AT6668 UART (optional) | Position, altitude, speed |
| Connectivity | WiFi / 4G LTE-M (optional) | SIM7080G modem |