Deployable tessellated transducer array for ultrasound focusing and bio-heat generation in a multilayer environment.

High intensity focused ultrasound (HIFU) has great potential to thermally ablate diseased tissues with minimal invasion. Yet, HIFU practice has limited cancer treatment potential since the absorption, diffusion, and reflection of ultrasound prevent HIFU from penetrating the body to deep and concealed diseased tissue. To explore a vision of deployable HIFU transducers, this research introduces an origami-inspired concept wherein a deployable tessellated acoustic array is employed to reduce the distance between the HIFU transducer and diseased tissues. A flat-foldable HIFU transducer array is considered, such that the compact shape is used to pass through the human body and then deployed into the operational form for treatment. Here a theoretical framework is developed to study the focusing and thermal heating capabilities of the tessellated array in a multilayer environment. It is observed that the wavefield and thermal elevation realized by the foldable array are functionally similar to those of an ideal arc-shaped transducer. Folding patterns that permit adequate curvature and high quality factor, and that balance slenderness and conformability are found to be beneficial for an ultrasound focusing practice. The efficacy of the analytical predictions are verified through direct numerical simulations. All together, the results encourage attention to foldable array concepts as potential means to advance in-vivo HIFU-based procedures.

Piecewise assembled acoustic arrays based on reconfigurable tessellated structures.

Physically reconfigurable, tessellated acoustic arrays inspired by origami structures have recently been leveraged to adaptively guide acoustic energy. Yet, the prior work only examined tessellated arrays composed from uniform folding patterns, so that the limited folding-induced shape change prohibits broad acoustic field tailoring. To explore a wider range of opportunities by origami-inspired acoustic arrays, here, piecewise geometries are assembled from multiple folding patterns so that acoustic transducer elements are reconfigured in more intricate ways upon array folding. An analytical model of assembled geometries and resulting acoustic wave radiation from the oscillating facets is formulated. Using the theoretical tool, parametric investigations are undertaken to study the adaptation of acoustic energy transmission caused by folding and modularity of the array assembly. A proof-of-concept specimen is fabricated and experiments are conducted to validate the theoretical model and to investigate the efficacy of the piecewise acoustic array concept. The total findings reveal that the assembly of tessellated acoustic arrays may emulate the wave radiation emitted by ideal acoustic sources of intricate shapes. Moreover, by exploitation of origami folding actions, the shape adaptations of the proposed arrays permit straightforward wave guiding opportunities for diverse application needs.