Abstract: The invention relates to an inductively operating sensor (1) for measuring the electrical conductivity of a fluid medium (2), having an excitation coil (3) to which an input signal is fed and a receiver coil (4) coupled to the excitation coil (3) via the fluid medium (2), the receiver coil (4) providing an output signal (IInd) which is a measurement of the conductivity of the fluid medium (2). The sensor (1) has means (5) for measuring a variable signal at the input of the excitation coil (3) for timely detection of damage to the windings of the excitation coil (3), the receiver coil (4), and/or to a power cable network for the sensor (1). The excitation coil (3) of the sensor is preferably fed by an input voltage (UErr) and the means (5) for measuring the variable signal preferably measure the input current (IErr) at the input of the excitation coil (3).

Abstract: A measuring system for determining physical and chemical properties of gases, liquids and solids includes a computing unit which is coupled with at least one sensor by means of a high capacity communications network. The system eliminates the need for dedicated cabling between the sensor and the computing unit.

Abstract: The invention relates to a device for measuring the concentration of ions, notably of hydrogen ions, in a measuring liquid using at least one ion-sensitive field effect transistor which is integrated into an electric circuit within the device in such a way that said circuit emits an output signal which serves as measure of the ion concentration in the measuring liquid. To provide a circuit which is as simple as possible and in particular comprises as few components as possible, the invention provides for the at least one pH-ISFET to be bridge-connected with at least three resistors.

Abstract: The invention concerns an opto-electronic sensor, in particular for the measurement of opaqueness in a medium, having a transmitter channel (6) irradiating light waves along a first axis (20) and with at least one receiver channel (8, 10) which detects light waves interacting with the medium and which cooperates within an evaluation unit. In order to optically isolate the transmitter and receiver channels from each other, the sensor is configured in such a fashion that a common window (12) made from an optically transparent material is provided for sealing the transmitter channel (6) and the receiver channel (8, 10) with respect to the medium to be measured and for coupling in and coupling out the light waves.