Overview

The MAX30105 is a high-sensitivity optical sensor module manufactured by Maxim Integrated (Analog Devices). Optimized for particle sensing, smoke/fire alarm detection, and PPG biometric monitoring, it integrates three internal LEDs (Red 660 nm, Infrared 880 nm, Green 537 nm), a high-sensitivity photodetector, ambient light rejection optics, and a low-noise 18-bit Delta-Sigma ADC.

While similar to biometrics-only chips like the MAX30102, the MAX30105 includes a Green LED that provides superior sensitivity for measuring smoke particles, airborne dust, and high-resolution heart-rate/pulse-oximetry ($SpO_2$) readings over $I^2C$ (0x57).

Quick reference

Pinout

Breakout module header & Qwiic / STEMMA QT connectors:

Specifications

Multi-LED Optical Particle Detection Logic

• Airborne Particle / Smoke Detection: When dust or smoke enters the optical chamber, light emitted by the Red, IR, and Green LEDs scatters off particles onto the photodetector (Mie scattering).
• Particle Size Discrimination: The short wavelength of the Green LED ($537\text{ nm}$) scatters strongly off fine smoke particles ($\le 1.0\ \mu\text{m}$), whereas IR ($880\text{ nm}$) scatters off larger dust grains ($\ge 2.5\ \mu\text{m}$). Comparing channel ratios allows distinguishing smoke from dust.

Wiring

Example (SparkFun MAX30105 Particle Sensor Library)

#include <Wire.h>
#include "MAX30105.h"

MAX30105 particleSensor;

void setup() {
  Serial.begin(115200);
  Wire.begin();

  Serial.println("SparkFun MAX30105 Particle Sensor Test");

  if (!particleSensor.begin(Wire, I2C_SPEED_FAST)) {
    Serial.println("MAX30105 not found! Check I2C wiring.");
    while (1);
  }

  // Setup sensor for particle sensing: 411us pulse width, 100 SPS, 400x ADC range
  byte ledBrightness = 0x1F; // Options: 0=Off to 255=50mA
  byte sampleAverage = 4; // Options: 1, 2, 4, 8, 16, 32
  byte ledMode = 3; // Options: 1 = Red only, 2 = Red + IR, 3 = Red + IR + Green
  int sampleRate = 100; // Options: 50, 100, 200, 400, 800, 1000, 1600, 3200
  int pulseWidth = 411; // Options: 69, 118, 215, 411
  int adcRange = 4096; // Options: 2048, 4096, 8192, 16384

  particleSensor.setup(ledBrightness, sampleAverage, ledMode, sampleRate, pulseWidth, adcRange);
  Serial.println("MAX30105 Particle Sensor Active.");
}

void loop() {
  uint32_t red = particleSensor.getRed();
  uint32_t ir = particleSensor.getIR();
  uint32_t green = particleSensor.getGreen();

  Serial.print("Red: "); Serial.print(red);
  Serial.print(" | IR: "); Serial.print(ir);
  Serial.print(" | Green: "); Serial.println(green);

  delay(200);
}

Common mistakes

• Covering sensor glass with opaque enclosures: The optical window must remain un-obstructed or protected by high-transmittance clear glass ($>90\%$ light transmission across $500\text{--}900\text{ nm}$).
• Overdriving LED currents: Operating all 3 LEDs at max current ($50\text{ mA}$) causes PCB thermal heating ($+2^\circ\text{C}\dots +4^\circ\text{C}$). Keep LED brightness values under $0x1F$ ($6.4\text{ mA}$) for continuous particle monitoring.

Notes

• MAX30105 vs MAX30102 vs MAX30100: MAX30105 includes 3 LEDs (Red, IR, Green) for particle/smoke sensing; MAX30102 includes 2 LEDs (Red, IR) for pulse oximetry.