Conversion of the chemical interaction into electrical signal in planar structure based on dry ADH layer with thin metal film contacts

Planar structure based on thin film metallic contacts and dry layer containing pyrroloquinoline quinone-dependent alcohol dehydrogenase (ADH) from Gluconobacter sp. 33 was developed for detection of ethanol in air. Exposure to ethanol vapour is inducing extra current flow in the layer and the electrical response signal is detected in a circuit without external power source. The response to ethanol in air is detected only if the ADH-dry-layers are sensitised by sequential connection–disconnection of the external voltage source. The response of the sensors is proportional to an amount of ethanol vapour in air. The sensitivity mechanism is interpreted by the model in which extraction (injection) of electrons from (to) ADH adjacent to the contacts is supposed. These processes are resulting in asymmetrical distribution of electrical charge in the ADH-dry-layers between the contacts. Excess mobile ions originated from chemical processes in the layer are producing extra current flow in response to ethanol.