COD measurement based on the integrated liquid drop sensor

A study on Chemical Oxygen Demand (COD) measuring method is reported, in which the COD value is measured by an integrated liquid drop monitor sensor without any reagent and chemical treatment. The integrated drop sensor consists of a liquid head, an integrated fiber sensor and a capacitor sensor. The capacitor sensor is composed of a drop head and a ring electrode. As the part of the drop head, the outline of the drop will be changed during the drop forming, which result in the variation of the capacitance. The fiber sensor is composed of two fibers that are positioned into the liquid drop. The light signal goes into the liquid drop from one fiber and out from the other one. A unique fingerprint of the liquid drop can be got by the data processing. The matching between the COD value of a liquid and the codes of the fingerprints in the database are presented and discussed.