General analysis method for the signal enhancement of microwave gas sensor though variation of energy loss

Microwave gas sensor (MGS) becomes a highlight recently because it can work at the room temperature (20 celcius) and has potential wireless application. However, there are still some problems such as low sensitivity and linearity. In this short communication, a novel analysis method based on variation of energy loss was proposed as sensor response for the first time. The as-prepared device is successfully used for NH3 detection based on commercial graphite powder which can achieve a low detection limit (1 ppm, 20 celcius), excellent selectivity and humidity-resistance (20-95% RH). Moreover, the sensor shows good linearity for low concentration range of NH3 from 1 to 5 ppm (R-2 = 0.999) or high concentration range from 10 to 200 ppm (R-2 = 0.99) through analyzing energy loss calculated by both reflection and transmission, which is more linear compared with that only using reflection or transmission. Therefore, this study provides a simple and universal method for response signal analysis, which can amplify the weak sensing signal then realize high-performance MGS.

Automated summary

In this study, a novel analysis method based on variation of energy loss was proposed for the first time, and a microwave gas sensor for NH3 detection was successfully developed. The sensor showed a low detection limit, excellent selectivity, humidity-resistance, and good linearity for NH3 concentration.