Cantilever with integrated Wheatstone bridge piezoresistive deflection sensor: analysis of force interaction measurement sensitivity

Atomic Force Microscopy (AFM) is a very sensitive technique to determine the surface topography. Recent developments enable investigations of other microtribological sample properties like elasticity, friction coefficients of the material, which is present on the observed surface. Although, measurements of small cantilever displacements are required in all AFM techniques. In our experiments we have used a cantilever with integrated Wheatstone piezoresistive bridge as a deflection sensor. This cantilever displacement detection system enables the investigations in UHV and low temperature conditions. In this paper we will analyze the sensitivity of the force observations with the piezoresistive Wheatstone bridge cantilever. We will examine how the detector response depends on the beam geometry. Noise considerations of the beam motion measurements method will be discussed. We will present the noise properties of the Wheatstone bridge piezoresistive detector and cantilever system. Measures for improving of the force measurements sensitivity will be proposed.