A MEMS sensor for measuring at least one measured variable, especially a density, a flow and/or a viscosity, a flowing fluid, is described, comprising: at least one microfluidic channel having a channel section excitable to execute oscillations; and an exciter system for exciting a desired oscillation mode, causing the channel section to execute oscillations in a predetermined plane of oscillation. The MEMS sensor has improved oscillation characteristics at least in part because the channel section is composed of an anisotropic material, having directionally dependent elasticity and which is spatially oriented such that a modulus of elasticity determinative for a stiffness of the channel section relative to deflections of the channel section perpendicular to the plane of oscillation is greater than a modulus of elasticity determinative for a stiffness of the channel section relative to deflections of the channel section in the plane of oscillation.