Mathematical Model of a Proposed Carbon Nanotube Sensor for Ultra Sensitive Acetone Sensing

Abstract: In recent years, MEMS/NEMS (Micro-/Nano Electro Mechanical Systems) sensors have attracted tremendous interest among researchers due to their low cost, quick response time, as well as high sensitivity and selectivity. In this paper, an ultra sensitive acetone sensor based on carbon nanotube (CNT) structure is proposed. In this device, a carbon nanotube is anchored to a substrate in one end, and the other end is free-standing. Piezoelectric activation is used to activate the vibration of such a carbon nanotube cantilever structure. If an acetone molecule is attached to the carbon nanotube, the resonant frequency of the cantilever will be changed for a certain amount. By sensing this certain resonant frequency change, the existence of a single acetone molecule can be detected. A theoretical model is developed to describe the vibration of the carbon nanotube cantilever structure. The resonant frequency change of the cantilever due to attached mass is analyzed. The proposed acetone sensor can achieve extremely high sensitivity in molecular level. It can be potentially used for sensing the trace acetone concentration in human breath, which leads to a quick, convenient, accurate and painless breath diagnosis of diabetics. Such breath diagnosis can greatly reduce the risk of blood-transmitted diseases in the traditional blood testing of diabetic’s diagnosis.