Optimal quality factor for tuning forks in a fluid medium

•We present a shape optimization formalism for tuning forks.•We define the optimal quality factor for a tuning fork in ambient air.•We fabricate the latter tuning fork and measure its quality factor.•We show the highest quality factor ever reported for a tuning fork in ambient air.

Resonator based sensing devices operated within a fluid medium often require maximal quality factors in order to enhance their performances. We present a tuning fork shape optimization formalism based on both analytical and numerical approaches, and identify the geometry with the lowest possible losses. We also report on the fabrication of a homemade tuning fork based on this optimization process, and experimental measurements show a quality factor of Q = 41000 in air at atmospheric pressure. This value represents, to the best of our knowledge, the record quality factor for a flexural resonator in ambient air.