1. A negative pressure gauge is an instrument used to measure negative pressure, which can measure pressure below atmospheric pressure. The working principle of the negative pressure gauge is based on the principle of the pressure sensor, and the negative pressure is determined by measuring the output signal of the pressure sensor.

2. The pressure sensor of a negative pressure gauge is usually a miniature pressure sensor that can measure very small pressure changes. When the negative pressure gauge is connected to a closed container, the pressure inside the container will exert pressure on the pressure sensor. This pressure causes the elastic element to deform, which changes the resistance value of the resistance strain gauge. This changing resistance value can be measured and recorded by the circuit of the negative pressure gauge to determine the size of the negative pressure inside the container.