Optimization of piezo-fiber scanning architecture for low voltage/high displacement operation

Piezo-based fiber scanning probes have emerged as low-cost and compact tools for various optical imaging modalities, allowing access to tissue sites that are hard to reach. These instruments exploit scanning of a fiber optic cable via a piezoelectric element, which is driven at the mechanical resonance of the extended fiber piece. However, the dynamics of the piezo-scanning structure is often neglected, resulting in an inefficient electromechanical conversion. This work presents a methodology, together with experimental evidence, to collectively optimize the geometries of the piezo-scanner and the extended fiber optic cable to achieve maximum displacement for a given drive voltage. Our findings suggest that matching the individual resonances of the fiber optics cable and the piezo-scanner alone, leads to optimum electromechanical conversion efficiency. Simulations, circuit model, and experimental results reveal more than x2 improvement in the achieved fiber displacement when piezo and fiber resonances are matched, as opposed to the unmatched (i.e., when piezo element length is varied approximately by ±20% from its optimal value) case. Besides offering lower power consumption for the actuation of the piezo-element, our findings paves the way for safer (electric shock-free) minimally-invasive procedures using the piezo-based fiber scanning probes, which is crucial for patient safety.