Ahmad Ghanbari - Department of mechanical engineering, University of Tabriz, P. O. Box ۵۱۶۶۴, Tabriz
Ali Rostami - Mechatronic research Lab., School of engineering- emerging technologies, University of Tabriz
Mir Masoud Seyyed Fakhrabadi - Department of mechanical engineering, University of Tabriz
Amin Yaghoobi - Department of mechanical engineering, University of Tabriz

Micro cantilevers have been considered to study surface stresses as a result of adsorption of molecules. It has been demonstrated that micro cantilevers are very sensitive to the adsorption of molecules and this has led to the use of micro cantilevers as sensor devices for the detection of binding of mercury vapor, moisture, and volatile mercaptans [1]. Micro mechanical cantilevers were first use as force probes in Atomic Force Microscopy (AFM) [2]. Changes caused in the output signal of piezoresistors and piezoelectrics by displacement at the end point of cantilevers or in the resonance frequency are sample mechanisms of detecting and sensing for micro/nano sensors. In present paper increasing in the sensivity parameter of piezoresistive micro/nano sensors will be investigated. Some theoretical but impractical suggestions to improve the sensivity of these sensors will be criticized and novel method based on nano composites will be introduced