The surface of the sensor chip has an array of individual sensors, each of which measures a different analyte. The sensors produce electrical signals in response to the analytes in the blood. The signal from each sensor is proportional to the concentration of analyte . The analytes which can be measured using Sphere’s micro-analyser technology include; glucose, pH, pO2, pCO2, K+, Ca2+, Na2+, hematocrit and lactate.

The individual sensors use one of three different transducer technologies; potentiometric (field effect transistor structure to measure the potential generated), amperometric (measuring the current generated) or conductimetric (measuring the change in conductivity). In order to make each sensors respond to a specific analytes (such as potassium or oxygen) they are covered with highly specific membranes.