A method for optimizing the design of a device includes interrogation means and a differential passive sensor, including a generator connected directly or indirectly to a reader antenna, a passive sensor including at least two resonators, a sensor antenna connected to the sensor. The method includes determining a set of curves PSAW as a function of the frequency of interrogation of the sensor, each curve being defined for a given impedance ZT representing the impedance of the Thevenin equivalent generator dependent on the impedance of the reader antenna, on the impedance of the sensor antenna and on the coupling between the two antennas, for a given sensor impedance ZSAW; selecting at least one curve PSAW from the set of predefined curves meeting two criteria: exhibiting two frequency peaks representative of a coherent differential sensor behavior; having a width at mid-height of the two the peaks below a threshold value; and determining the sensor antenna exhibiting the sensor antenna impedance correlated to the curve PSAW selected for the predefined SAW sensor.