Microcantilever based sensors can be used for detection of specific target molecules in a solution. In conventional mode of sensing, receptor molecules are immobilized on the cantilever surface and the chemical interaction between receptors and ligand molecules causes surface stress change resulting in cantilever deformation; however, in the competition mode of sensing, the cantilever surface is covered with complex molecules and after immerging cantilever in the solution of target molecules, ligand molecules diffuse away from the cantilever surface and causes cantilever deflection. In this method, the rate of ligand dissociation can be measured as a sensing tool.

In this report, both mode of sensing is considered and theoretical models are developed to understand the mechanism of cantilever tip deflection in conventional mode of sensing and ligand dissociation rate in competition mode of sensing.

For the conventional mode of sensing, it is shown that, the molecular interaction model, which is based on interaction energy between double strand DNAs, can predict the cantilever deflection better than entropy model.

Also, it is proved that the competition mode of sensing can be a good method of sensing and its advantages and limitations are shown.