Metal-free flat horn for ultrasonic surgical devices

Ultrasonic surgical devices are traditionally designed as bolted Langevin transducers (BLTs), in which a bolt pre-stresses a stack of piezoelectric rings between two metallic end masses. This configuration offers high mechanical stability and acoustic power handling capability, but it suffers from increased bulk, weight, and self-heating issues, significantly restricting the ergonomic suitability for hand-held surgical procedures.Recently, planar ultrasonic scalpels have emerged as a more compact, lightweight, and thermal-efficient alternative. Unlike BLTs, which operate in the thickness mode of the piezoelectric stack, planar scalpels utilize the length-thickness mode of the piezoelectric plates bonded with epoxy near the longitudinal displacement nodes of a flat metal horn. However, their limited volume of active material reduces the dynamic performance of the devices. This work presents a novel planar design in which the flat horn is made entirely from a PZT plate, eliminating the metal counterpart. The goal is to maximize the PZT volume and minimize the epoxy usage, thereby enhancing the electromechanical performance.