Nano-electromechanical Systems (NEMS) are extremely sensitive detectors of physical parameters. In recent years, the applications of NEMS in mass sensing have gained importance through demonstrations of mass sensitivities at the atomic level and mass measurements of single protein molecules. These demonstrations show that is possible to perform biochemical analysis through NEMS mass measurements (NEMS Mass Spectrometry) especially for physiologically important large molecules and biostructures. The NEMS literature so far has always treated these large molecules as point-particles; however considering the miniaturization trend of NEMS and the significant size of targeted large molecules, this assumption is getting less applicable for experiments. In this project, we demonstrate how we can theoretically and experimentally measure the total mass of an arbitrary mass distribution on NEMS through simultaneous measurements of multiple modes. Furthermore we show that this method can be used to obtain important spatial information about the measured molecule, such as its average position, the variance of its density distribution, the skewness of the molecule etc. This extra characterization modality expands the capabilities of NEMS devices: one can obtain, for instance, the effective density of the sample being measured by combining mass and extent (variance) information. With the proposed technique it is possible to obtain an approximate image of an adsorbed molecule by reconstructing the density profile using the measured moments of the distribution. In the project, multimodal NEMS devices will be fabricated, electronic and vacuum systems to perform the measurements will be constructed and up to the third moment (mass, position, variance and skewness) of different analytes (nanoparticles and biomolecules) will be obtained. The project will be the first step for the development of a novel, powerful NEMS sensing tool and facilitate the integration process of the researcher.