Product Specification

Analogue Front End AFE

Alphasense air quality sensors require low noise electronics to optimise their performance. We have worked for many years perfecting our circuits, so you can now take advantage of our low noise circuits for easiest use.

The family of Analogue Front End (AFE) circuits are designed for use with the A4 air quality sensors. Connect the AFE with A4 sensors to your multtiplexed ADC and you are recording air quality data immediately.

Features of the AFEs include:

· 2 sensor, 3 sensor, 3 sensor+PID and 4 sensor versions are available. The AFEs are analogue potentiostat circuits with on-board power regulation and reference voltages: there is no digital circuitry on the AFEs.

· Power requirement: 650uA per channel; for example, 3 sensor AFE with sensors requires only 2 mA.

· Although electrochemical sensors require + and – power supplies, the negative supply is generated on the AFE so you need only supply 3.4 to 6.4 V (low noise) and analogue ground.

· Each AFE includes a Pt1000 located next to the centre sensor for correct temperature compensation. Pt1000 output is 1mV/oC but the room temperature must be set through your software.

AFEs are not user adjustable:

· Offset voltage for each sensor is defined in the calibration document (two offsets for each sensor: working electrode offset and auxiliary electrode offset) which you program into your software.

· AFE gain is preset. The calibration document also states the mV/ppb calibration for each working electrode which you program into your software.

Accessories include cables (specify 50 mm or 200 mm length), gassing hoods for calibration checks and mounting pillars, sealing gaskets and hardware for easy fitting to your hardware.