Experimental investigation of the decrease in the quality factor and calculation of the mechanical properties of quartz tuning forks from analogous electrical parameters

Quartz tuning forks (QTFs) are being more frequently adopted instead of micromachined cantilevers as force sensors in scanning probe microscopes due to their mechanical stability, high quality factors, and wide availability at low costs. Mass-produced QTFs are typically housed in vacuumsealed canisters, and this necessitates the removal of the vacuum canisters to make necessary modifications such as attaching a tip or an optical fiber. Commonly, the decrease in the quality factor after the removal of the canister is attributed to an increase in air damping with no further investigation of other possible causes. We carried out several experiments with QTFs before and after the canisters were removed. Despite a vacuum level below 10 ⁻⁵ Torr, all investigated QTFs exhibited decreased quality factors once the protective canisters had been removed. We present possible causes for this observation by analyzing optical microscope images. Also, complete mechanical and electrical characterizations of the QTFs are presented, taking advantage of the analogies that exist between mechanical and electrical systems.