Negative ion detector is a special instrument measurement of gases in the atmosphere of the ion, it can measure the concentration of the air ions, distinguish the positive and negative ions polarity, and can according to the difference of the ion mobility to distinguish the size of the detected ions. Negative ion detector mainly includes polarization power, the ion collector, micro current amplifier and dc power supply four parts. The parallel electrode method: bad effects to solve the electrostatic and outside air, but to occupy the advantage on the cost of production has an advantage comparing with the price, although there are certain drift, but basically can determine the concentration of the positive and negative ions. Detection principle of capacitor: capacitor is more advanced, it is solved through a cylinder can be a very good airflow and the influence of static electricity, can be more convenient. Relevant product information: pitot tube, pitot anemometer, intelligent wind speed air flow meter, negative ion detector, digital micro pressure gauge.