Pulsed excitation of eigenmode in photoacoustic resonators for gas sensing

This paper explores the principles and advantages of utilizing a pulsed measurement mode to enhance the energy efficiency of photoacoustic (PA) gas sensing systems configured with an acoustically resonant measurement setup. The proposed approach involves the intermittent excitation of one of the resonator's eigenmodes, which serves as the PA measurement cell (PA cell). By leveraging the resonant characteristics of the PA cell, the method maximizes sensitivity and signal-to-noise ratio (SNR) while significantly reducing power consumption compared to conventional continuous-excitation PA gas sensors. Experimental results demonstrate that with a peak current of less than 100 mA at 3.5 V for a 300 ms excitation pulse, a sensitivity of 9 mV/ppm can be achieved. Furthermore, by adjusting the duty cycle and the on-time duration, the system allows for flexible tuning of both power consumption and resolution, making it suitable for a wide range of applications. The study also highlights the importance of accounting for the dynamic characteristics of the system, such as settling times and signal delays, to avoid operating during transient states that could lead to incomplete or distorted measurements. This balance between energy efficiency and stable, steady-state operation is critical, particularly in applications where both precision and responsiveness are required.