Deflection, Frequency, and Stress Characteristics of Rectangular, Triangular, and Step Profile Microcantilevers for Biosensors

Abstract

This study presents the deflection, resonant frequency and stress results of rectangular, triangular, and step profile microcantilevers subject to surface stress. These cantilevers can be used as the sensing element in microcantilever biosensors. To increase the overall sensitivity of microcantilever biosensors, both the deflection and the resonant frequency of the cantilever should be increased. The effect of the cantilever profile change and the cantilever cross-section shape change is first investigated separately and then together. A finite element code ANSYS Multiphysics is used and solid finite elements cantilever models are solved. A surface stress of 0.05 N/m was applied to the top surface of the cantilevers. The cantilevers are made of silicon with elastic modulus 130 GPa and Poisson’s ratio 0.28. To show the conformity of this study, the numerical results are compared against their analytical ones. Results show that triangular and step cantilevers have better deflection and frequency characteristics than rectangular ones.

Variable width based stepped MEMS cantilevers for micro or pico level biosensing and effective switching

“…The microcantilever's deflection depends on its geometrical dimensions (length, width and thickness), material properties and applied load [22][23][24][25]. It increases with increment in its length and decrement in its thickness [20,22,26,27].…”

Closed-form empirical relations to predict the static pull-in parameters of electrostatically actuated microcantilevers having linear width variation

“…Later, the investigations reported by Abdalla et al (2005), Najar et al (2005), Raulli and Maute (2005), Lemaire et al (2008), and Joglekar and Pawaskar (2009) substantiated this inference for the cases involving deformable electrodes. In other instance, geometrical alterations to the referential prismatic beam have been exploited to enhance the sensitivity of biosensors (Chen and Yu 2007;Ansari and Cho 2009), and passive tuning of the eigenfrequencies of AFM optical levers (Rinaldi et al 2008). With reference to several new contexts and applications of MEMS which demand conceptually newer designs, the potential of using nonuniform electrodes in place of the uniform prismatic electrodes has been well reckoned, and efforts are being made to facilitate the electromechanical analysis of nonuniform beams (see Li et al 2009).…”

Geometry optimization of uncoated silicon microcantilever-based gas density sensors

“…For bio-sensing applications and in order to improve the overall (static-mode and dynamic-mode) sensitivity of a microcantilever, as measured by the product of static deflection and resonant frequency, M.Z. Ansari et al [18] proposed using a non-uniform cantilever cross-section (giving increased k and decreased meff) and reducing the fixed-end area (increasing the static deflection). The authors suggested triangular or step cross-section profiles instead the conventional rectangular one.…”