In this paper, we propose a single-input single-output sensing scheme for three analytes via nonlinear mode localization that is experimentally verified using a coupled triple cantilever array. By introducing electrostatic nonlinear breaking of structural symmetry, this scheme can distinguish the two analytes absorbed on the hanging wall on both sides. Single input and single output can be realized by electrostatically driving one side cantilever and piezoelectrically outputting the response of the other side cantilever, and greatly simplifying the structure. In addition, driving one side cantilever to the nonlinear resonance area can ensure high resolution. Finally, the sensing error is greatly reduced by decoupling the complex relationship between multiple modes and multiple analytes. This work not only broadens the theoretical content of modal localization, but also opens new approaches for quantitative detection of multiple analytes.