Biological identification system with integrated sensor chip

A method of detecting the presence or measuring the quantity of a target analyte in a sample, comprising:

• positioning the sample on a sensor, the sensor including a working electrode, a reference electrode and a counter electrode on a substrate, the reference electrode consisting of a single layer of an electrically conductive material and a self-assembly monolayer, the self-assembly monolayer being bonded to the layer of electrically conductive material and including biotinylated thiol molecules that include a sulfur bonded directly to the layer of electrically conductive material;
• conducting an analysis of the sample that includes controlling a potential difference between the reference electrode and the working electrode while measuring a current flowing through the working electrode, wherein
• the potential is controlled so as to cause a redox reaction between a component in the sample and the working electrode, and
• the current through the working electrode is balanced by a current through the counter electrode;
• and
• employing the measured current to determine the presence or quantity of a target analyte in the sample.