Sensoranordnung zum Nachweisen eines Stoffes in einer Fluessigkeit

A sensor arrangement for the detection of a substance in a liquid comprises an oscillator circuit containing an oscillating transistor and a feedback circuit, and an oscillating crystal driven by said oscillator circuit, one side of the oscillating crystal being in contact with the liquid. In order to increase the sensitivity of such a sensor arrangement, which can be designated a biosensor, reduce phase noise and ensure reliable oscillation even with high viscosity liquids without causing the coupling of electric fields in the liquid, the emitter of the oscillating transistor is connected to a parallel circuit from an emitter resistor and to the oscillating crystal, whereby the feedback circuit comprises an adjustable phase shift circuit and an amplitude limiter circuit.