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high-sensitivity picoammeter and the cathode is polarized
against the internal reference. Driven by the external partial
pressure, nitrous oxide from the environment will penetrate
through the sensor tip membrane and be reduced at the
metal cathode surface. The picoammeter converts the
resulting reduction current to a signal. The internal guard
cathode is also polarized and scavenges oxygen in the
electrolyte, thus minimizing zero-current and stabilization
time.
