Electrochemistry is not just pH and conductivity. Currently on the market are Ion Selective Electrodes (ISE) which determine Fluoride, Chloride, Iodide, Sulfide, Cyanide, Ammonia, Nitrate, Sodium, Calcium, Potassium, and other ions. Other common probes are biological oxygen demand (BOD), oxidation reduction potential (ORP), and dissolved oxygen (DO). Electrochemical detectors are being developed which determine organic and bio-molecules in addition to ions. One of the best examples of this is the electrochemical determination of glucose.
Electrochemical biosensors capitalize on the specificity of biological molecules in the sensor for the analyte in question. When the biosensor attached to the working electrode is in the presence of the analyte a catalytic or binding event occurs which results in an electrical signal. The potential of the electrochemical cell is monitored by a transducer and the change in potential is proportional to the concentration of the analyte. One of the advantages of electrochemical determination of molecules is detection levels on the order of picograms, another is fast response time. Combine these advantages with the specificity of biological molecules and you have a powerful detection method. In the future expect new electrochemical products for the detection of biological and organic molecules.