Oscillatory-mode oxygen sensor

A high-temperature (∼ 800°C) O
2
sensor is described based on O
2
pumping and sensing with ZrO
2
, O
2
-concentration cells. The cells are incorporated in a ceramic structure that defines an enclosed volume which communicates with a gaseous ambient of interest by means of a small leak. An oscillatory pumping procedure is described whose period is proportional to at least the first power of the desired ambient O
2
-partial pressure over a substantial pressure range. The device has potential application for monitoring engine air-to-fuel ratio based on the O
2
content of exhaust gas.