Electronic Circuits for Polarographic Oxygen Sensors
A polarographic oxygen sensor (POS) is a two-terminal chemoelectric transducer; a suitable polarizing voltage across the sensor leads produces an output current which, ideally, is proportional to the partial pressure of oxygen in the sample. In membranecovered sensors this signal is quite small and current is first converted into a voltage and then amplified to drive either a meter or a strip chart recorder or for input to an analog-to-digital converter. Membrane-covered POS show a large dependence on temperature, the signal increasing by 1%–6% for a rise of 1°C . Consequently measurements have to be made under thermostatic conditions or there has to be some method of compensating the temperature effect. If a readout in units of concentration is desired, a correction for the variation of oxygen solubility as a function of temperature (App. A) must also be made. A block diagram for a circuit for a temperature-compensated oxygen detector is shown in Fig. 1.
KeywordsPermeability Assure Cali Controled
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- 1.Burke A (1981) Linearizing thermistors with a single resistor. Electronics 54:151–154Google Scholar
- 2.Forstner H ,Ruetzler K (1971) Measurement of the microclimate in littoral marine habitats. In: Barnes H (ed) Oceanogr Mar Biol Annu Rev, vol VIII. George Allen Unwin Ltd, London, pp 225–248Google Scholar
- 3.Graeme GG (1973) Applications of operational amplifiers, third-generation techniques; the Burr Brown electronic series. McGraw-Hill, New York, p 225Google Scholar
- 4.Graeme GG, Tobey GE, Huelsman LP (1971) Operational amplifiers, design and applications. McGraw-Hill, New York, p 468Google Scholar
- 5.Hitchman ML (1978) Measurement of dissolved oxygen. J Wiley Sons and Orbisphere Corp, New York, p 255Google Scholar
- 6.LaForce RC (1976) Application of operational amplifiers to polarographic oxygen sensor systems. Appendix. In: Fatt I (ed) Polarographic oxygen sensors. CRC Press, Cleveland, Ohio, pp 255–263Google Scholar
- 7.Philbrick-Nexus Research (1969) Applications manual for operational amplifiers. Philbrick-Nexus Corp, Dedham, Mass, p 115Google Scholar
- 8.Vassos BH, Ewing GW (1972) Analog and digital electronics for scientists. Wiley Interscience, New York, p 405Google Scholar
- 9.Yellow Springs Instrument Co (1973) Instructions for YSI 5331 oxygen probe. Yellow Springs Springs Instrument Co, p 4Google Scholar