A respiration sensor for use with a medical ventilator, suitably between the patient airway and the Y-piece where the expiratory and inspiratory flows separate, comprises a tube with a flap mounted therein, the flap being resiliently and magnetically biassed to a datum position extending transversely across the tube interior, but the flap being movable in opposite senses from its datum in response to gas flow from the tube, and means for selectively detecting such opposite movements. The flap pr...

This specification discloses an improved electrochemical gas sensor comprising a closed end stabilized zirconia tube to which a porous layer of powdered zirconia is applied so as to be intimately bonded to the tube, and a layer of porous electrode material which in the use of the sensor is exposed to the gases to be analyzed. The provision of the porous layer of powdered zirconia substantially improves the bonding of the outer electrode layer to the zirconia tube. In the preferred embodiment a f...

An optic displacement sensor includes first and second optic circuits which optic circuits include bi-directional means for a light supply path to and a light return path from a light reflecting surface means. The first optic circuit is a reference signal circuit, and the second optic circuit is a measuring signal circuit. Means are provided for directing light into the light supply paths for the pair of optic circuits, and means are provided whereby the light from the light supply paths of the ...

A piezoelectric beam structure for a vibrating beam force sensor in which three coplanar beams of piezoelectric material are spaced side by side and supported between respective common mountings at either end. The two outer counterbalancing beams in operation flex in opposite phase to the center main beam, with each beam flexing in a direction normal to the beam plane. A force sensor which includes this piezoelectric beam structure.

A sensor for measuring large magnitudes of A.C. current utilizes a conductive member having a higher-resistance element parallelled by a pair of elements with lower, and substantially equal, resistance and so arranged as to cause cancellation of magnetic field effects upon the higher-resistance element due to a flow of current through the lower-resistance elements. Thermal-effect compensation of the higher-resistance element of the sensor is also disclosed. Active load termination of a current-s...

An oxygen sensor which exhibits a change in electrical resistance as a function of oxygen partial pressure comprises at least one of strontium ferrate, barium ferrate and strontium barium ferrate, in which part of the iron in the ferrate lattice has been replaced by at least one element of valency greater than 3, such as titanium, cerium, niobium or tantalum.

An electro-mechanical load sensor is in the form of a mechanical resonant system with electrostatically coupled electrodes. The mechanical system is formed from a silicon wafer by a selective etching process and comprises a filament of between two terminations 12 and 13 carrying transverse plates M.sub.1 and M.sub.2. Electrostatic (capacitive) coupling to plate electrodes E.sub.1, E.sub.2, E.sub.3 in a self-exciting circuit drives the system. The resonant frequency for angular S vibrations with ...

A sensor uses the principle of surface plasmon resonance (SPR) to monitor the progress of the reaction between a sample and a sensitive layer (for example an antibody layer). The layer is applied to the rear surface of a metallic film formed on the surface of an optically transmissive component in the form of a hemicylindrical lens and slide. Collimated light from a source is applied via a lens which focuses the incoming beam to a focus at a point to form a fan-shaped spread of light incident at...

Sensing methods and apparatus for monitoring the surface condition of a body of water including floating sensor units deployed on the water surface employing reflected infrared radiation detectors to sense the presence of floating hydrocarbons from an oil spill or floating industrial waste, sewage or the like. Telemetry signals report the surface condition of the body of water to a central receiver unit.

A temperature sensor for a motor vehicle comprises a composite of PTC and NTC thermistors (1, 2, 3) whose overall temperature characteristic (c) is negative with a plateau (P) centered on the normal working temperature (88.degree. C.) to be sensed, so that tolerances in the sensing system and normal fluctuations of the working temperature will tend not to be registered by the vehicle temperature gauge. Thus only abnormal variations in temperature caused by a fault or overload condition will be i...