Abstract: A driving device for a vortex mixing apparatus comprises holders for holding a mixing unit of a type having at each opposite end a pumping diaphragm for imposing a pulsatile flow on a liquid passing through a primary channel in the unit. Two pistons are each arranged to cooperate with a respective one of the diaphragms and to reciprocate between a retracted position clear of the unit and an extended position in which it extends into a housing of the unit and compresses the respective diaphragm. Driving mechanisms are normally arranged to reciprocate the pistons in phase at the same frequency such that when one piston is moving from its retracted position to its extended position the other is moving from its extended position to its retracted position and vice versa. Control mechanisms are arranged, upon stopping of the driving mechanisms, to cause both pistons to adopt retracted positions so that the unit may be inserted into, and removed from the holders without interference from the pistons.

Abstract: A peristaltic pump has an occluder ring (1) and a rotor (5) with drive rollers (16,17) for squeezing a flexible pipe (11) against the ring (1). The rotor has dogs (12a,12b) for overriding a bight of the pipe to load it through a gap (10) between a cover plate (8) of the rotor and the ring (1).

Abstract: An optical sensor comprises a probe (10) and an annular optical element (13) coupled optically to a pair of optical fibres (18). Light transmitted down one fibre is reflected around the element (13) and back up the other fibre to a photodetector. The level of light received by the photodetector is dependent upon the amount of light lost from the element (13) as a result of characteristics of the surrounding medium. The presence or absence of a surrounding liquid medium may thus be sensed and a motor (34) operated to suck liquid up through the probe, when the liquid is present.

Abstract: The application relates to a method and apparatus for testing the concentration of a selected atomic scale species in a thick liquid, such as blood. The blood flows through a chamber that is in part defined by a microporous dialysis membrane permeable to atomic scale species. A measuring cell including a second chamber filled with a clean liquid is defined by the other plane of the membrane. The measuring cell incorporates a sensor having an electrode coated with a material permeable only to a selected ionic species.

Abstract: A blood monitoring system for the contents of blood bag B utilizes rigid optically clear tablet (16) bonded to rough outer surfaces of the walls of the bag to provide windows through the bag. The bag is gripped by a pair of tongs T the jaws of which have openings to receive the tablets. The outer surfaces of the jaws have ribs (33) and buttons (36) to locate the tongs, and hence the bag, accurately in position in a monitoring device, with the windows (16) in alignment with an optical system of the device.