What are the reasons for the long response time?

Response time refers to the time required for a sensor to come into contact with a target gas and output a stable signal. Long response time can affect the real-time monitoring ability of sensors for changes in gas concentration.

The gas diffusion rate is one of the important factors affecting the response time. If the gas diffusion channel design of the sensor is not reasonable, such as a small aperture or a long channel, it will hinder the rapid diffusion of the target gas to the surface of the sensitive material, thereby prolonging the response time. For example, in some portable gas sensors, if the air inlet is not designed properly, the speed of gas entering the interior of the sensor will slow down, resulting in an increase in response time.

The properties of sensitive materials can also affect response time. The particle size and specific surface area of sensitive materials can affect their adsorption and reaction rate towards the target gas. The smaller the particles and the larger the specific surface area, the larger the contact area between the sensitive material and the target gas, the faster the reaction rate, and the shorter the response time. On the contrary, if the sensitive material particles are larger and have a smaller specific surface area, the response time will be prolonged.

The circuit design of sensors also has a certain impact on response time. The components such as capacitors and inductors in circuits will form a certain time constant, which affects the transmission and processing speed of signals. If the circuit design is unreasonable and the time constant is too large, it will cause the response time of the sensor to be prolonged.

How to shorten the recovery time?

The recovery time refers to the time required for the sensor to recover from the target gas to its initial state. Shortening the recovery time can improve the reuse efficiency and detection frequency of sensors.

Optimizing the structural design of sensors can improve gas diffusion conditions and promote rapid detachment of target gases from the surface of sensitive materials. For example, using a porous structure as a sensitive material carrier can increase the flow channels of gas, improve the diffusion speed of gas, and thus shorten the recovery time.

Choosing appropriate sensitive materials is also key to shortening recovery time. Some sensitive materials can quickly desorb and return to their initial state after reacting with the target gas. For example, some organic semiconductor materials have good reversibility and can complete the desorption process in a shorter time, shortening the recovery time.

Proper heating treatment of the sensor can also accelerate the desorption of the target gas. In some gas sensors, heating elements are installed inside the sensor to heat the target gas after it is separated from the sensor, increasing the temperature of the sensitive material and promoting the desorption of the target gas, thereby shortening the recovery time. However, it should be noted that the heating temperature and heating time should be controlled within a reasonable range to avoid damage to the sensor.