Mechanically-induced fiducial marker system for event-based synchronization of independent recording instruments

Many experimental and clinical measurements require simultaneous acquisition from independent instruments that do not share a clock. We describe a device that enables such pairings via event-based synchronization: an electrical trigger from one instrument drives an Arduino-controlled stepper actuator that produces a brief mechanical event at a location sensed by the other instrument, leaving a fiducial marker for post-hoc temporal alignment. The motivating application is synchronization of high-resolution manometry (HRM) with transperineal ultrasound for phenotyping stress urinary incontinence. Bench characterization yielded a device latency of $802.5\text{μ}\text{m}\pm 46.2\text{μ}\text{m}$ (mean $\pm$ SD, $n=30$ ), of which the electromechanical response of the actuator accounts for $\approx 84\%$ of the mean latency and the dominant share of the trial-to-trial variation (i.e. the SD of $46.2\text{μ}\text{m}$ ). For the ultrasound-HRM application, the synchronization uncertainty is $\approx 6\text{ms}$ ( $n=30$ markers), set by the HRM rather than the device, whose intrinsic jitter contributes negligibly. The approach generalizes to instrument pairings in which one instrument provides a stable electrical trigger with a known relation to its recording timeline and the other is a mechanically-sensitive receiver of adequate bandwidth, provided the marker does not contaminate the signal of interest.