The invention discloses a quasi-volumetric sensing system and method. Plural short-range order (SRO) units are configured on the carrier of a quasi-volumetric device, and arranged as an array, i.e. a long-range order (LRO) unit. Protrusions, configured on the SRO units, can modify the wettability of the carrier to control the liquid volume retained thereon so that the precise volume of the liquid sample or droplets are calculated. Based on the applied force on the LRO unit and the gradient of hydrophilicity-hydrophobicity on the surface, the redundant volume of the liquid sample is removed. Macromolecules, e.g. antibodies, complements, receptor proteins, aptamers, oligosaccharides or oligonucleotides, configured on the protrusions are coupled to specific molecules in the liquid sample or droplets so as to determine characteristics of the specific molecules. Therefore, the open chip device of the invention can be used to achieve the quasi-volumetric measurement and the analysis of specific molecules.