SCANNING OPTICAL SENSOR FOR THE MEASUREMENT OF DISSOLVED-OXYGEN AND BOD

A scanning optical sensor based on the oxygen quenching of luminescence has been developed for the measurement of dissolved oxygen and five-day biological oxygen demand (BOD5). The sensing element is a silicone rubber film with embedded ruthenium(II) complex. It is attached to the inner surface of a transparent vessel in which dissolved oxygen needs to be measured. An optical scanner with an excitation light source and an optical cable connected to a light detector are used to monitor the oxygen concentration inside the vessel. The scanner provides the excitation light and senses the emitted light from the sensing element without direct physical, contact with the vessel. Therefore, one optical scanner can be used to monitor the dissolved-oxygen concentrations in many vessels in one batch. A correlation is found for linearizing the responses of luminescence quenching with the dissolved-oxygen concentration, which enables two-point calibrations of the sensors to be carried out. Effects of temperature and steam sterilization on the sensor are also studied