Molecular modeling of the conductivity of carbon nanotubes under different temperature and humidity

At present, the sensor is widely used and its types are varied, such as biological sensor, gas sensor, humidity sensor, optical sensor, pressure sensor, etc. However, the performance of many sensors remains to be optimized. For instance, the problems of activity of the biofilm, detection range and sensitivity life in biosensor have limited the development of its own. On the other hand, in gas sensor, the detection of hysteresis, degradation of serious phenomenon is widespread. And in the humidity sensor, humidity is the parameter which is hard to detect accurately, for serious impact of atmospheric pressure and temperature. However, with the emergence of CNTs based sensors, the above problems are hopefully solved. Owing to the excellent properties with CNTs, such as promoting electron transfer, large edge plane/basal plane ratio, high electrical conductivity, etc, CNTs based sensors have a higher sensitivity, lower detection limit and faster electron transfer kinetics than traditional ones. In addition, CNTs film has a very large specific surface area, and a strong interaction between the surrounding medium, therefore, CNTs film is seriously sensitive to the humidity of external environment, which has obvious humidity sensitive features. Due to the different using environment of CNTs sensors, the research of conductibility of CNTs under the different temperature has a great significance. Therefore, molecular modeling approach was adopted to analyze the conductivity of different type of CNTs like (9, 9) and (9, 0) CNTs within the scope of sensor operating temperature (-20°C-100°C) and different humidity conditions. It was found that the forbidden gap of (9, 9) and (9, 0) CNTs are basically decreased with the increase of temperature. Meanwhile the conductivity of CNTs under different moisture circumstances was also analyzed. The forbidden gap of CNTs has changed little after filled with pure water molecules This study provides a rational way using mol- cular modeling to evaluate and design CNTs for various applications such as biosensors and chemical sensors.