Current-to-voltage convertor for measurement of oxygen

A highly sensitive, miniature, inexpensive circuit for the measurement of PO2 in vivo has been described. The circuit is constructed from a current-to-voltage convertor, clamping circuit, differential amplifier, and reverse voltage and overvoltage protector. The design of the circuit allows us to apply voltage bias to the measuring electrode while grounding the preparation. The clamping circuit holds the selected bias voltage constant while the differential amplifier subtracts this bias potential from the PO2 signal yielding an output voltage that is proportional to the current sensed by the oxygen electrode. The circuit is protected from reverse voltage and overvoltage.