Device and method for improving the stability and detection limit of acoustic wave sensors

A method for improving the stability and detection limit of acoustic wave sensors, comprising:

• a) monitoring, with a sampling period of between 0.01 and 1 second, a resonance frequency and dissipation of two piezoelectric resonators integrated in a same substrate, wherein one piezoelectric resonator acts as a sensor while the other piezoelectric resonator acts as a reference and storing in memory the sampling data;
• b) injecting a sample on a surface of the piezoelectric resonator that acts as the sensor with a flow rate between 1 and 200 μl/min;
• c) applying a Daubechies Wavelet transform to signals acquired in a) and storing the data in memory;
• d) applying a process in which all wavelet components obtained in c) whose magnitude is lower than a certain threshold, Th, are properly filtered and their data is stored in memory;
• e) performing a numerical calculation of a time derivative of the wavelet transform components of the two resonators obtained in d) and storing the results in memory;
• f) calculating a cross-correlation coefficient between each sample n of the derivative of the wavelet transform components of the sensor signal and the reference obtained in e), wherein this calculation is performed in a window of length w samples, and storing the results in memory;
• g) calculate a new corrected time derivative of the wavelet transform components of the sensor resonator from the coefficients obtained in section f), whose calculation depends on the obtained value of the correlation coefficient as follows:
• when the calculated coefficient indicates a high probability of correlation of P<5%, the derivative in the window is calculated by minimizing the error in the linear fit between the coefficients of the derivative of the original wavelet components of the sensor and the reference;
• when the calculated correlation coefficient does not indicate a high probability of correlation of P>5%, the derivative in the window is calculated by subtracting the coefficients from the derivative of the original wavelet components of the sensor and the reference;
• and
• storing the results of this calculation in memory;
• h) reconstructing the wavelet coefficients of the resonance frequency and dissipation of the resonator acting as the sensor by numerical integration of the data obtained in g), and keeping the result of the integration in memory;
• i) generating a corrected time signal of the resonance frequency and dissipation of the sensor by calculating an inverse wavelet transform of the data obtained in h).