In this work we describe the use of a micro-scale array of polysilicon doubly clamped beams, based on the approach of embedding microfluidic channels inside the resonators, as an innovative platform for multiplexed biosensors. Finite element methods in COMSOL were employed to simulate the structural mechanical behavior and to know the conditions to determine the frequency response in order to achieve optimal sensitivities and quality factors. Particularly, we studied the effect of microchannel cross-section area, length and sidewall thickness respect to the microchannel dimensions with the objective of injecting solutions of different densities. By integrating additional multiphysics models we analyzed the governing microfluidics, and we estimated that a maximum pressure difference of 7 MPa along the microchannels is required to establish an optimum water flow rate of 0.1 μl/min, which is adequate for biosensor applications. To validate the simulations we compared the thermal noise response of a fabricated array of microbridges in air, and we obtained resonant frequencies between 700 KHz and 1 MHz, in good agreement with our simulated results but with downward frequency shifts due to the undercut effect after fabrication.