Sensitivity analysis of cantilever biosensors

Abstract

Microcantilever sensors are commonly used as chemical and biological sensors. Interactions between the functionalisation layer on the cantilever and the analytes in the sample cause the cantilevers to bend. When the analyte concentration is low, these interactions are localized. Then, the same concentration can cause different deflections, depending upon the locations of interactions. The deflections will thus depend on the location of interaction, as well as the concentration of the analyte. This paper presents a model to calculate the deflection, when uni-axial surface stresses are distributed and localized. Results of this model are compared with finite element method simulation results. Biaxial stresses are then considered, and the one dimensional model is shown to be a valid approximation when the stresses are not applied at the ends. Using the model, characteristic response curves of a cantilever, when the surface stresses are localized, are obtained. The probability of determining a concentration based on an observed deflection is shown to be as low as 20%