Fourier transform mechanical spectroscopy of micro-fabricated electromechanical resonators: A novel, information-rich pulse method for sensor applications

A new sensing method employing a computer-designed broadband voltage pulse sent to an electromechanical resonator is suggested and demonstrated. The pulse spans a user-defined bandwidth around a user-selected center frequency so as to include at least one mechanical resonance. The transient voltage pulse excites mechanical resonance through the piezoelectric effect. The current response signal from the device is recorded and subjected to FFT. Components of the response due to electrical impedance and mechanical resonance are separated and tracked with time upon exposure to solvent vapors, helium, or CO 2. Data are shown for both polymer coated quartz tuning forks and piezoelectric microcantilevers with sub-ppm sensitivity for some analytes.