The invention is an electromechanical resonator, comprising a fixed portion and an oscillator oscillating at a resonant frequency and comprising a fluidic channel. The channel defines a fluidic circuit, can receive a fluid, and can be deformed at the resonant frequency. The resonator includes a waveguide, defining a photonic circuit, guiding a light wave between an input and an output of the waveguide and being able to be deformed at the resonant frequency. The waveguide input can be connected to a light source and the waveguide output can be connected to a photodetector able to form a signal representative of the light wave propagated by the waveguide towards the photodetector, the light wave being modulated at a frequency dependent on the resonant frequency. A variation in a mass of the fluid, inducing a variation in the resonant frequency, may be detected via the signal formed by the photodetector.