Carbon monoxide detector...

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Hi.

Disemboweled a defunct CO detector (not a smoke detector) to find out what the sensor would be like. And got

 

There is a cylinder the size of a fat AA cell. has only one ~0.1 mm hole behind a tightly packed dessicant sachet blocking it. Seems filled with liquid.

The incomprehensible part is how can CO easily enter such tiny and blocked orifice promptly to signal the alarm, in still air...

 

By searching, seems it is a

Pasted from the web :

"Electrochemical Carbon Monoxide Detectors

This is an electrochemical cell that is designed to produce current in relation to the amount of carbon monoxide present in the air. Carbon monoxide is oxidized to carbon dioxide at one electrode while oxygen is consumed at the other electrode. Sulfuric acid is the usual electrolyte that separates the electrodes. The current triggers the alarm or can even be used to quantify the amount of carbon monoxide that is present."

 

And it looks like ----> http://images.teamsugar.com/files/upl1/1/12981/01_2008/22cc51ad22642d81_CO.jpg

 

Do you know the operation principle/rationale of the sensor ?