Photoionization detector and method of operating same

A device configured to be operated in compensation mode, the device comprising:

• a counter electrode on a top surface of an electrically insulative substrate configured to apply a first electric potential;
• a sensing electrode on a bottom surface of the insulative substrate configured to apply a second electric potential;
• and
• a third electrode configured to apply a third electric potential and having a pin passing through the substrate and separating a current path of the counter electrode from a current path of the sensing electrode, wherein the first and third electric potentials are same or generally same in value, and the second electric potential is generally higher than the first potential.

A device configured to be operated in a block mode, the device comprising:

• a counter electrode on a top surface of an electrically insulative substrate configured to apply a first electric potential;
• a sensing electrode on a bottom surface of the insulative substrate configured to apply a second electric potential;
• and
• a third electrode configured to apply a third electric potential and having a pin passing through the substrate and separating a current path of the counter electrode from a current path of the sensing electrode, wherein the second and third electric potentials are same in value, and the second electric potential is generally higher than the first potential.