High-Sensitivity Photoacoustic Gas Detection Based on a PMN-PT Piezoelectric Cantilever

This work reports the first implementation of a lead magnesium niobate-lead titanate (PMN-PT) single-crystal cantilever as an acoustic sensor in a photoacoustic spectroscopy system for trace-gas detection. Benefiting from the exceptionally high piezoelectric coefficient and strong electromechanical coupling of PMN-PT, the cantilever efficiently converts weak photoacoustic pressure fluctuations into electrical signals. In the absence of an acoustic resonator, the system exhibits a signal responsivity of 0.0894 V/ppm and achieves a minimum detection limit (MDL) of 0.88 ppb with an averaging time of 100 s. The normalized noise equivalent absorption coefficient (NNEA) is 2.43 × 10⁻⁹ cm⁻¹WHz^−1/2. These results indicate that PMN-PT single crystals constitute a promising sensing material for high-sensitivity photoacoustic gas detection.