A sensor detects analytes in a fluid medium by measuring the conductivity of a layer on a carrier with the layer contacting an electrode pair. The layer interacts with the analyte and is improved in that the sensor has a long-term stability and the indication provided by the sensor is completely reversible....http://www.google.com.hk/patents/US5334351?utm_source=gb-gplus-share專利 US5334351 - Sensor for detecting analytes in a fluid medium
