1.1.6. Nitrogen Dioxide Sensor (NO2)

1.1.6.1. Introduction

The ESDK-NO2 board measures atmospheric nitrogen dioxide levels using an electrochemical cell that produces a current from a redox reaction.

1.1.6.2. Schematic diagram

1.1.6.3. Theory of operation

A SPEC Sensors ULPSM-NO2 module provides an interface to the electrochemical cell that converts the current output into a linear voltage output. As this signal from the ULPSM module is high impedance, a unity-gain amplifier configuration buffers the signal before being fed into an ADS1119 16-bit, four channel ADC that is polled over the I2C bus.

1.1.6.4. Board layout