Embedding microfluidic channel inside a microcantilever has drastically improved the sensitivity of microcantilever biosensors. The sensing principles in suspended microfluidics have been either stress induced deflections or mass based frequency variations. However, the suspended microfluidics can be designed to use flow forces as the sensing principle. In this study, a 3D suspended polymeric microfluidics (SPMF3) is designed with flow plane orthogonal to bending plane. This design innovation, enables the SPMF3 to detect physical properties of bioelements through microcantilever deflections induced by flow force variations inside the embedded suspended microfluidics. Here, the earlier approaches in design and modeling of suspended microfluidics are presented and explained in detail. First, a 2D suspended microfluidics is modeled and its sensitivity to flow forces is analyzed. Modifying the microchannel plane position with respect to cantilever neutral plane results in different microcantilever deflections and consequently biodetection sensitivity. In order to verify the concept of the 3D suspended polymeric microfluidics (SPMF3) for physical study of bioelements, first, a finite element analysis (FEA) of a sample flow inside the microfluidic system is performed. In this modeling, microfluidic-microcantilever interactions and the system sensitivity to flow forces are studied. The SPMF3 deflections with different aperture design is modeled and the sensitivity of each design is analyzed. Three different types of apertures namely, straight aperture, nozzle and diffuser have been modeled and the results show that the diffuser aperture has better sensitivity to flow forces under same working conditions. According to the FEA results, flow force can be employed as a sensing principle of 2D suspended microfluidics. However, sensitivity of the 3D suspended microfluidics is drastically increased and can be tuned for any specific biodiagnostic application using different aperture designs.