Abstract: A device of the type which uses a moving boundary for detecting a fluid analyte. The device includes an impervious container (10, 12, 14) having a fluid entry aperture (20) and containing two contiguous layers. One of the layers is a detection layer (16) in the form of a sheet comprising a reagent to generate a signal by a reaction initiated by the analyte. The other layer (18) is a spreading layer permeable by the analyte position such that analyte entering the container spreads within the spreading layer. The device can be used, for example, as a gas monitor for indicating exposure to hazardous gases or vapours.

Abstract: A method of growing or maintaining mammalian cells comprises applying a culture of the cells to a surface of a porous inorganic membrane support. The support is preferably a transparent anodic aluminium oxide membrane. The support carrying cells (44) growing or being maintained thereon may comprise a short tube (30) and a disc (32) of the porous inorganic membrane, the disc being sealed round its periphery to the tube adjacent one end thereof.

Abstract: An analytical method using a sensor of the enzyme electrode type is provided for determining in a sample the concentration of an analyte reactive with an enzyme present on the sensor to produce an electrochemically active species detectable by the sensor, which comprises applying a potential across the sensor to cause an electrical current to flow therethrough, contacting the sensor with the sample thereby causing a change in the current flow and, when a working potential is applied across the sensor, determining the concentration of the analyte as a function of the change in the current characterized in that at some time before the working potential is applied and the concentration of the analyte is determined a potential significantly in excess of the working potential is applied, whereby to reduce the period required to establish a signal sufficiently stable to permit the determination to be effected.