We report the successful realization of quartz-enhanced photo-acoustic (QEPAS) sensors employing quartz tuning forks (QTFs) with novel geometrical parameters. We investigated the influence of QTF sizes on the main resonator parameters, in order to identify the best design parameters optimizing the QTF figures of merit for optoacoustic gas sensing. To evaluate the QTF acousto-electric energy conversion efficiency, we operated the QEPAS sensors in the near- IR and selected water vapor as the target gas. QTFs are forced to resonate at both the fundamental and the first overtone vibrational mode frequencies. Our results shows that two QTF designs exhibit an higher quality factor (and consequently an higher QEPAS signal) when operating on the first overtone mode with respect to the fundamental one.