Micro dehumidifier protects opto-electronics from moisture

15 February 2013

Rosahl is a solid state micro dehumidifier designed to protect sensitive electronic and opto-electronic devices from moisture.

It uses a solid polymer electrolyte to remove moisture from enclosures from 250ml up to 2m³.

According to specialist technical consultancy ERA Technology, printed circuit boards (PCBs) can also suffer from a variety of problems if the surface is contaminated with electrically conducting materials. Combined with moisture, these results in a lowering of resistance between tracks and pads and can lead to corrosion of metals.

Rosahl utilises a solid state polymer ionic membrane (SPE) to electrolytically decompose and remove moisture from the air by electrolysis when a 3V dc voltage is applied. There are no moving parts so Rosahl dehumidifiers are silent and vibration free. Operation is maintenance free and the devices have a low running cost.

When a voltage is applied to the porous electrode attached to the SPE the moisture on the anode side (dehumidifying side) dissociates into hydrogen ions (H+) and oxygen: the hydrogen ions migrate through the membrane to be discharged on the cathode (moisture discharging) side where they react with oxygen in the air, resulting in water vapour being discharged. If the membrane is reversed a humidifying effect is achieved.

The dehumidifying SPE membrane is mounted in a plastic case which is normally installed in the side of the enclosure to be dehumidified. Several versions are available: the flat membrane dehumidifiers are suitable for drying up to two litres and measure 24 x 30 x 5.5mm, and can be mounted inside or outside the enclosure. A similar capacity version is available in an M12 fitting.

Rosahl membranes can also be use to humidify an enclosure, or hold a balanced humidity when fitted with the appropriate controls.

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