How Do Nitrogen Dioxide Sensors Work?

The first step in determining the speed of a sensor is to determine how long it takes for the sensor to respond to nitrogen dioxide. This can be measured empirically by the response time ratio. The response time ratio depends on the test method and the length of time the sensor is exposed to the test gas. For example, in the present studies, the sensor was exposed to the test gas for ten minutes. The response time ratio was determined by dividing the sensor’s output after one minute by the output of the sensor after ten minutes.

Detection range

The International Gas Detectors range of NO2 sensors is suitable for both fixed and portable monitoring applications. They are an important tool for monitoring the levels of dangerous nitrogen dioxide in industrial environments. The sensor measures the concentration of NO2 in air and alerts workers to the harmful levels. There are four standard detection ranges for NO2 sensors: 0-1 ppm, 0-5 ppm, 0-20 ppm, and 0-50 ppm.

The Detection range of no2 sensor offers highly accurate and sensitive performance. They are available in standard 3, 4, and 5 series sizes with pre-calibrated 4-20mA transmitters and mV output boards.

Electrochemical working principle

The electrochemical working principle of a nitrogen dioxide sensor depends on how the gas molecules react with the sensing electrode. During an open-circuit condition, CO and oxygen molecules will be oxidized on the working electrode. This reaction is proportional to the gas concentration in the air. This reaction is then measured.

The electrochemical reaction will produce an electrical current as the gas diffuses through the porous membrane into the working electrode. The current produced by this reaction will flow through an external circuit, where it will be sent to the sensor. It is also possible to use a counter electrode that will produce the opposite reaction as the working electrode.

The sensor cells used for this experiment had five 7/64-inch-diameter inlet holes. The test gas contained a concentration of 10-20 ppm of nitrogen dioxide. As shown in Figures four and five, the sensitivity of this sensor can be increased by increasing the total surface area of the inlet holes. Using this principle, the electrochemical sensors of the present invention can provide a substantially linear output over the range 0 to 300 ppm N02.

Response time

In the present study, the response time of a nitrogen dioxide sensor was measured for a wide range of NO2 concentrations. We used a P-N junction to improve the electron transmission rate, thereby reducing the sensor’s recovery time. Although the maximum response time did not depend on the NO2 concentration, the response time at lower NO2 concentrations was decreased.

The performance parameters were stable over a three-cycle test. As a result, the sensor can be used for continuous monitoring. The selectivity of the sensor for NO2 gas was confirmed, and the response time was less than a second.


Calibration of nitrogen dioxide sensors is an essential part of ensuring the accuracy of the data generated by NO2 instruments. Several methods of calibration are available to meet various customer requirements. Some of the methods can be performed onsite and others require a visit to a calibration laboratory. Depending on the needs of the customer, an onsite calibration may not be sufficient.

During calibration, the sensor is exposed to the gas to be measured. The sensor’s response curve is then calculated. The calibration curve should be linear, and should not deviate from it by more than a few parts per million. In some cases, manufacturers may perform a multipoint calibration, which involves reading the sensor at many different points.

Reference electrodes

A reference electrode for a nitrogen dioxide sensor has an electrochemically active surface. It is preferably made of silver sulfate. The electrode’s surface area is typically in the range of 4.6 to 1500 m2/g. The reference electrode and working electrode are electrically connected through an electrolyte within the sensor’s housing.

The nitrogen dioxide sensor can measure the concentration of the gas by determining the current density of the gas. The measurement of this gas is a useful method for monitoring the effect of nitrogen dioxide levels on human health and the environment. Several electrochemical methods have been developed for this purpose.

The nitrogen dioxide electrochemical sensor has been used in industrial settings. The current sensors have the disadvantage of being unsuitable for medical environments. Moreover, the output of the sensor depends on the concentration of oxygen in the test environment. In industrial settings, oxygen concentrations are relatively constant, whereas in medical environments, oxygen levels vary considerably over time.