Histotripsy Transducer Array Tuning for Curved Element Reliability
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Solution Overview
Problem
Current Histotripsy transducer manufacturing is challenging due to stress-induced failures during curving processes, limited driving frequencies, and low piezoelectric composite volume fraction, leading to physical and electrical failures.
Innovation Solution
A transducer array design with a concave emitting surface, varying well shapes, and matching layers, along with capacitors for frequency tuning, to enhance manufacturing efficiency and frequency flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the piezoelectric composite is curved to match the desired radius of curvature, then the transducer can focus ultrasound energy correctly, but stress-induced failures occur during the curving process
Solution Approach 1:
The transducer face is segmented into multiple independent piezoelectric elements rather than using a single continuous composite. This segmentation allows each element to be manufactured separately in its final curved configuration, eliminating the need to curve a large continuous composite which causes stress-induced failures.
Solution Approach 2:
Each piezoelectric element is manufactured with the desired spherical curvature already built-in during fabrication, rather than attempting to curve a flat composite afterward. This approach allows the elements to achieve the correct radius of curvature without experiencing the stress-induced failures that occur when curving large continuous composites.
2Speed
If the transducer frequency is decreased for better tissue penetration, then the therapeutic effectiveness improves, but the piezoelectric composite thickness must be reduced which increases manufacturing failures
Solution Approach 1:
By segmenting the transducer into multiple independent elements, each element can be manufactured with optimized thickness for the desired frequency without compromising the overall transducer reliability. Smaller individual elements are more tolerant of the thickness reductions needed for lower frequency operation.
Solution Approach 2:
The transducer design allows independent adjustment of element thickness to match the desired operating frequency. By changing the thickness parameter of individual piezoelectric elements, the transducer can operate at lower frequencies for better tissue penetration while maintaining manufacturing reliability through the segmented architecture.
3Power
If the piezoelectric volume fraction is increased to improve ultrasound output, then the therapeutic effectiveness improves, but the epoxy filler has less room to widen during curving which increases failure risk
Solution Approach 1:
Segmenting the transducer into smaller elements allows for higher piezoelectric volume fractions in each element without increasing overall failure risk. The smaller scale of individual elements means that even with reduced epoxy content, there is still sufficient material flexibility to achieve the required curvature without stress-induced failures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design allows for cost-effective and reliable production of transducers capable of producing optimized ultrasound waves for Histotripsy therapy, overcoming manufacturing challenges and frequency limitations.
Implementation Method 1
a plurality of piezoelectric elements individually disposed in the plurality of wells and contacting the proximal surface of the array shell, each of the plurality of piezoelectric elements configured to transmit ultrasound energy
Implementation Method 2
a plurality of first matching layers individually disposed in the plurality of wells and contacting the proximal surface; and a second matching layer disposed on the distal surface of the array shell
Implementation Method 3
at least one interconnect assembly facilitating a plurality of electrical connections from a signal generator to each of the plurality of piezoelectric elements, the at least one interconnect assembly including one or more capacitors at each electrical connection configured to tune an operating parameter of the plurality of piezoelectric elements to the signal generator
Implementation Method 4
Histotripsy, or pulsed ultrasound cavitation therapy, is a technology where extremely short, intense bursts of acoustic energy induce controlled cavitation (microbubble formation) within the focal volume
Data Source
AI summary
A histotripsy therapy system configured for the treatment of tissue is provided, which may include any number of features. Provided herein are histotripsy and/or ultrasound transducer arrays, and associated systems and methods that provide efficacious non-invasive and minimally invasive therapeutic, diagnostic and research procedures. The transducer arrays provided herein can be individually tuned such that transducer arrays with different sizes, focal lengths, or transducer element sizes may work at a desired operating frequency with the same signal generator.