Patent ID: 7043821

Claim:
A method of manufacture of a device for sampling a fluid, the device comprising a pre-chamber having an interior surface and a first volume, the pre-chamber being capable of exerting a first capillary force, the device further comprising a sensing chamber in fluid communication with the pre-chamber, the sensing chamber having an interior surface and a second volume, the sensing chamber being capable of exerting a second capillary force, wherein the first volume is not less than the second volume, and wherein a differential exists between the capillary forces, the differential being sufficient to cause flow of fluid from the pre-chamber to substantially fill the sensing chamber, the method comprising the steps of: forming an aperture extending through a sheet of electrically resistive material, said aperture defining a side wall of the sensing chamber; mounting a first thin layer to a first side of the sheet and extending over the aperture whereby to define a first sensing chamber end wall; mounting a second thin layer to a second side of the sheet and extending over the aperture whereby to define a second sensing chamber end wall in substantial overlying registration with the first thin layer, whereby said sheet and layers form a strip; removing a section of the strip which overlaps the sensing chamber and an edge of the strip whereby to define a notch; mounting a first covering layer to a first side of the strip and extending over the notch whereby to define a first pre-chamber wall; and mounting a second covering layer to a second side of the strip and extending over the notch whereby to define a second pre-chamber wall in substantial overlying registration with the first covering layer.