Sense toxins/sewage gases by chemically and biologically functionalized single-walled carbon nanotube sensor based microwave resonator

In this work the complex permittivity and microwave absorption of toxins/sewage gases and functionalized single-walled carbon nanotube sensors in a perturbed microwave resonant cavity are studied with the aid of a kinetic model. The results show that the real permittivity decreases and the imaginary permittivity increases with increasing the electron density; however, the real permittivity increases and the imaginary permittivity decreases with the collision frequency increasing. The results furthermore show that low electron density and high collision frequency can greatly reduce the microwave absorption, while high electron density and low collision frequency can increase the microwave absorption. The microwave absorption shifts to high frequency with increasing the electron density. The microwave absorption, in contrast, shifts to low frequency with the collision frequency increasing. The kinetic model may be used to study the effects of gas pressure on the complex permittivity and microwave absorption.