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How do you design a dust sensor

Samsung dust sensorI have just had a ‘why didn’t I think of that’ moment.

Samsung’s VC21F50UKGC vacuum cleaner has a dust detector that indicates if there is much dust going up the pipe – to alert the user they are over a particularly dusty bit.

What an nice idea, and..

.. I wonder how that works?

My initial guess was capacitive – looking at the dielectric constant of the air and dust between two plates.

But that seems a little fussy and complicated to keep calibrated.

Leading to second guess – optical, either transmissive or reflective – much easier to calibrate (and no flow-induced static build-up) – if it could be kept clean enough.

Anyone know?

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1 Comment

  1. Steve Kurt
    August 18, 2014 19:09

    I would lean towards an IR reflective method. You could compensate for the layer of crud over the optics by doing an initial calibration with zero airflow (I think).

    There will be a point where there will be enough gunk over the emitter and detector that calibration can’t compensate, though. This might be where material science is needed to come up with a window that doesn’t let dust and stuff adhere to it.

    Or maybe it could use an intial cleaning process, where a jet of air is directed at the window to clean the gunk off?

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