Finite element static displacement optimization of 20–100 kHz flexural transducers for fully portable ultrasound applicator

This paper focuses on the development of a finite-element model and subsequent stationary analysis performed to optimize individual flexural piezoelectric elements for operation in the frequency range of 20–100 kHz. These elements form the basic building blocks of a viable, un-tethered, and portable ultrasound applicator that can produce intensities on the order of 100 mW/cm2 spatial-peak temporal-peak (ISPTP) with minimum (on the order of 15 V) excitation voltage. The ultrasound applicator can be constructed with different numbers of individual transducer elements and different geometries such that its footprint or active area is adjustable.The primary motivation behind this research was to develop a tether-free, battery operated, fully portable ultrasound applicator for therapeutic applications such as wound healing and non-invasive transdermal delivery of both naked and encapsulated drugs.It is shown that careful selection of the components determining applicator architecture allows the displacement amplitude to be maximized for a specific frequency of operation. The work described here used the finite-element analysis software COMSOL to identify the geometry and material properties that permit the applicator’s design to be optimized. By minimizing the excitation voltage required to achieve the desired output (100 mW/cm2ISPTP) the power source (rechargeable Li-Polymer batteries) size may be reduced permitting both the electronics and ultrasound applicator to fit in a wearable housing [1].

► Stationary finite element analysis (COMSOL) of flexural transducers enabling low voltage operation.
► Displacement optimization of flexural transducers for therapeutic applications.
► Low frequency (<100 kHZ), Low intensity (∼100 mW/cm2), low profile ultrasound applicator.
► Several therapeutic applications (wound healing and transdermal drug delivery), due to small size and portable operation.