Although becoming popular in label-free, rapid, and real-time assaying of biomolecules, the sensitivity of microcantilever biosensors decrease as the concentration of analytes decrease. The sensitivity of a microcantilever biosensor depends on its deflection that occurs due to interaction between the analyte and its bioreceptor molecule. Therefore, designing a cantilever biosensor which can assay analytes in low concentrations is important. In this study, we propose a new cantilever design that can detect and measure analytes in extremely low concentrations. By introducing a narrow strip towards the fixed end of the rectangular cantilever, we can reduce cantilever flexural stiffness and hence increase the deflections at its free end. A commercial finite element analysis software ANSYS is used to analyze and verify the proposed model. Results show the proposed cantilever bends nearly twice the conventional for same surface stress. This high sensitive design can significantly increase the sensitivity and range of cantilever biosensors. Furthermore, using a combination of conventional and proposed cantilevers array on same chip, a universal microcantilever biosensor can be designed that can assay analytes in large dynamic concentration range.