Gas sensor

A gas sensor comprising:

• a sensor case;
• a subassembly mounted to the sensor case, wherein the subassembly comprising:
• a tubular gas-sensing element case fixed to the sensor case, the gas-sensing element case having a first open end for receiving a gas to be monitored and a second open end opposite to the first end;
• a gas-sensing element configured to measure a concentration of a specific component of the gas;
• and
• a first circuit board comprising a driving circuit configured to drive the gas-sensing element mounted to the first circuit board, the first circuit board being disposed in the gas-sensing element case, a moisture-proof material being disposed over at least one side of the first circuit board, wherein a gas-sensing chamber is defined by the first circuit board and an inner tubular surface of the gas-sensing element case, and opens at the first open end of the gas-sensing element case;
• a second circuit board mounted to the sensor case, wherein the second circuit board comprises a control circuit configured to control the gas-sensing element via the driving circuit, the second circuit board being disposed in a position separate from the gas-sensing chamber such that the second circuit board is kept out of contact with the gas to be monitored;
• and
• a communication line through which the first circuit board in the subassembly is communicatively coupled with the second circuit board.