The invention concerns a sensor for measuring ultra-violet radiation over long periods. Interference filters remove unwanted radiation and a phosphor selected from zinc cadmium sulphide activated by copper and having a hexagonal crystal structure or strontium chlorosilicate activated by divalent europium with the phosphor matrix having an orthorhombic crystal structure, which converts the transmitted ultra-violet into radiation acceptable to a selenium photovoltaic cell.

A moisture sensor which includes a moisture sensitive material and electrodes in communication with the moisture sensitive material, the moisture sensitive material containing a substantially electrically insulating substance derived from a colloidal dispersion and, distributed in or on the substance, an electrically conducting substance.

A solid sensor, for sensing a physical parameter such as pressure, comprises a resonantly vibratable beam formed across a cavity in a substrate by micro-machining, and arranged such that changes in the parameter vary its resonant frequency. The beam either consists of or has deposited on it a material exhibiting piezo-electric effect, so that vibration of the beam can be excited by using the effect. This is achieved using light, either by forming a photodiode in the substrate in or near the beam...

A sensor for measuring sulphur dioxide in flue gases comprises a sensing electrolyte of doped .beta.-alumina or doped NASICON. The dopant serves to increase conductivity at grain boundaries in the sensing element or at the electrode interface, thereby to increase the rate of depolarisation. Preferred dopants are copper silver and nickel.

In a micromachined silicon pressure sensor comprising a resonantly vibratable beam supported on a diaphragm, the beam is indirectly excited into resonant vibration by directing an optical excitation signal at the beam resonant frequency onto a part of the sensor other than the beam, preferably the diaphragm. Preferably, the optical excitation signal is of a wavelength to which the sensor is fairly transparent, and is directed through the beam and diaphragm to be absorbed by a suitable coating on...

Sensors for the qualitative and quantitative determination of K.sup.+ ions in aqueous systems are described, which consist essentially of a carrier and an active layer applied to this carrier, whereby the active layer contains a polymer in which is dispersed at least one modified valinomycin, in which a radical of a fluorescence dye which emits in long waves, preferably an acridine or fluorescein, with an emission wave length of >550, is covalently bound.

A device for monitoring the electrical conductivity of an electrically conductive fluid comprising at least two electrical coils for immersion in the fluid. One of the coils constitutes a coil to be energized with an alternating current and the other in use constitutes a detection coil. The coils are arranged relative to one another so that in use they are mutually inductively coupled and are inductively coupled by the fluid. An electronic circuit is provided which includes a power supply for su...

A sensor system is formed with sensors and a controller which are detachably attached to a network to be connected together. Each sensor stores an interface program for its own and the controller serves to upload these interface programs from the individual sensors and use the uploaded interface programs to access these sensors under optimum conditions.

Example embodiments of pressure sensors are illustrated and described.

A sensor (1) for capacitively measuring the distance to a stationary or passing object. The sensor has an electrode (2) that capacitively couples with the object and is formed from an electrically conductive ceramic material. The electrode is substantially surrounded by a housing (4) formed from an electrically non-conductive ceramic. The electrically conductive and electrically non-conductive ceramic materials are chosen to that they have the similar thermal expansion coefficients so that the s...