Abstract: The inventive microsensor and method for regulating the sensitivity primarily aims at measuring the nitrate concentration in a surrounding medium by use of a concept named “Migrational Sensitivity Control” (MSC). The sensitivity of the sensor is regulated by impressing an electrical potential difference or an electrical current between a surrounding medium, e.g. waste water, containing a primary substance to be measured, and a substance chamber inside the microsensor. The microsensor contains bacteria which metabolizes the primary substance into a secondary substance, the concentration of which is proportional to the conentration of the primary substance to be measured. By measuring the concentration of the secondary substance the concentration of the first substance can be found. By varying the impressed voltage or current, the sensitivity of the microsensor can be controlled.

Abstract: The invention relates to a method and a microsensor for measurement of transport coefficients like diffusivity or flow velocity. The microsensor has a reservoir provided with a mouth and a transducer. The transducer has a tip placed in the mouth, which can be provided with a membrane or insert. The reservoir contains one or more gases or one or more liquid-dissolved substances intended for the diffusion through the mouth into an area or field of a medium outside the mouth of the reservoir. The transducer measures the partial pressure of the gas or the concentration of the liquid-dissolved substance in the mouth, whereby transport coefficients of diffusivity or flow velocity are determined. Preferably, the gradient of the partial pressure or the concentration is determined.