Abstract: Aqueous membrane permeable by mass transport to a charged and uncharged species of interest, comprising a synthetic polymeric material and a surface active agent which is miscible with the synthetic polymer. The surface active agent is distributed throughout the membrane and is present in an amount such as to provide for the permeability of the membrane to the species of interest.

Abstract: A membrane for use in a sensor having a detection arrangement. The membrane is of a cellulosic material incorporating a hydrophobic agent (e.g. isopropyl myristate) and is permeable by diffusion to an analyte species of interest to be detected directly or indirectly by the detection arrangement.

Abstract: Membranes incorporating surfactants of a synthetic polymer rendered permeable by the surfactant. The membranes are blood compatible and may be used in biosensors and also for dialysis. The preferred polymer is PVC.

Abstract: Sensor devices, and analytical methods using them, employing a detector protected from direct contact with samples being examined by a membrane made of a polyurethane modified with a non-ionic surfactant. The detector is preferably an electrode of conventional type (e.g. plantinum metal, optionally with pseudo, counter or reference electrodes) but especially an enzyme electrode. The surfactant may be incorporated into the polyurethane by admixture or by reacting chemically with the polyurethane, and is preferably a condensate of ethylene oxide with a compound containing a hydrophobic moiety—especially with a hydroxy-compound, e.g. an alkylated phenol, fatty alcohol or a sorbitan ester. Conveniently, the polyurethane membrane may contain up to 20 parts per 100 of polyurethane and be up to 10 microns thick, and formed by dip-coating an electrode. Measurements, using electrodes, may be made amperometrically.

Abstract: An amperometric sensor device comprising a working electrode, a reference/pseudo-reference electrode and a permselective membrane incorporating a charged organic species. The electrodes are in intimate contact with the membrane and are on a side of the membrane opposite to the side exposed to a fluid sample. The charged organic species provides a conducting path through the membrane between the electrodes.