Sensitivity Enhancement of Microcantilever Biosensors Using Hybrid Thickness Profile Designs

Microcantilever-based biosensors are widely used for label-free detection of biological and chemical species due to their high sensitivity and scalability. The performance of these sensors is governed by surface-stress-induced deflection and resonant frequency characteristics. However, according to the Stoney equation, these two parameters are inherently coupled, limiting the achievable sensitivity of conventional rectangular cantilevers. In this study, a novel Hybrid Thickness Profile (HTP) microcantilever design is proposed to enhance overall biosensor sensitivity through strategic thickness engineering. Three HTP configurations were investigated: HTP-I, with a thin section near the free end; HTP-II, featuring a centrally located thin section; and HTP-III, in which the thin section is positioned near the fixed end. All designs were analyzed using three-dimensional finite element simulations in ANSYS Workbench. Silicon microcantilevers with dimensions of ۵۰۰ × ۱۰۰ × ۱ μm were subjected to a uniform surface stress of ۰.۰۵ N/m. The results show that relocating the compliant thin section toward regions of higher bending moment significantly increases deflection and overall sensitivity. Among the proposed designs, HTP-III achieved the highest performance, with a maximum deflection of ۲۴.۵۵ μm and an overall sensitivity of ۱۳.۷۵ μm·kHz, corresponding to enhancement factors of ۸۷.۷× and ۱۰.۰×, respectively, compared to a conventional rectangular cantilever. Structural analysis confirmed that the maximum von Mises stress in all configurations remained well below the silicon yield strength of ۱۷۲.۳ MPa, ensuring mechanical integrity. These findings demonstrate that hybrid thickness profiling provides an effective and fabrication-compatible approach for developing highly sensitive microcantilever biosensors.

کلیدواژه ها:

Microcantilever Biosensor ، Thickness Engineering ، Sensitivity Enhancement ، Natural Frequency Analysis ، Finite Element Method