Ultrasound patch for detecting fluid flow
Inventors
EIBL, Joseph • Kenny, Jon-Emile S. • Demore, Christine • MUNDING, Chelsea • Brown, Jeremy • Boyes, Aaron
Assignees
1929803 Ontario Corp D/b/a/ Flosonics Medical • Daxsonics Ultrasound Inc • 1929803 Ontario Corp
Publication Number
US-11744539-B2
Publication Date
2023-09-05
Expiration Date
2039-04-05
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Abstract
An ultrasound patch includes one or more transmit and receive piezoelectric transducer elements. In some embodiments, the transducer elements are positioned on a ramp on a patient pad of the patch that is configured to fit within an anatomic space between the trachea and the sternocleidomastoid muscle to orient the transducer elements toward a carotid artery. In some embodiments, a flexible phased array transducer includes a number of pillar piezoelectric elements joined by a flexible adhesive with metal electrodes deposited thereon. The phased array transducer is mounted to a flexible circuit board that allows the transducer to bend and conform to a subject's anatomy.
Core Innovation
The disclosed technology relates to ultrasound transducers configured to measure flow in a vessel. In some embodiments, the transducer includes one or more transmit (TX) transducer elements spaced from one or more receive (RX) transducer elements, arranged to direct ultrasound energy into a subject and receive echo signals from moving body fluids. The transducer elements may be arranged in a frame with an open back to provide an air gap behind the transducers, enhancing acoustic impedance mismatch and signal quality.
The invention also includes configurations where transducers are mounted on a ramp in an elastomeric patient pad, which angles the transducers relative to the skin surface to direct ultrasound energy toward vessels such as the carotid artery. Flexible phased array transducers composed of pillar piezoelectric elements joined by a flexible adhesive with metal electrodes can conform to a subject's anatomy, allowing beam steering and improved patient comfort. The technology enables continuous and non-invasive measurement of fluid flow, Doppler shifts, and related hemodynamic parameters such as central venous pressure (CVP).
The problem being solved addresses limitations of conventional ultrasound flow measurement systems that require manual operation and cannot be used hands-free. Traditional transducers are held at angles that are nearly orthogonal to vessel flow, reducing Doppler efficiency. Additionally, rigid designs can be uncomfortable and inefficient for continuous monitoring. The disclosed technology aims to provide a wearable, hands-free ultrasound patch with improved transducer designs that produce angled ultrasound beams via mechanical ramps or flexible phased arrays, enabling continuous flow measurement in vessels such as the carotid artery and internal jugular vein while improving patient comfort and signal quality.
Claims Coverage
The claims detail eight main inventive features focusing on the ultrasound patch's structure, transducer arrangement, flex circuit design, and assembly methods.
Ultrasound patch with flex circuit and hinged transducers
An ultrasound patch comprising a flex circuit with first and second transducer elements angularly positioned relative to each other via hinging of the flex circuit, supported by a frame inside a housing, with control electronics and a battery contained within the housing configured to be secured on patient skin over the vessel.
Frame designs securing transducer elements
Frames include angled side rails securing edges of transducer elements or acoustically transparent backing supports supporting the transducers along their length, providing fixed angular orientation and air gaps behind rear surfaces of transducers.
Use of spacers and lenses with transducers
Spacers positioned around the perimeter of rear surfaces form air gaps behind transducers; lenses (convex, concave, or tilted concave) and protective layers can interface with front surfaces to focus ultrasound beams and protect transducers.
Differential angular positioning of transducers
The frame holds first and second transducers at different angles to overlap transmit and receive beams in an area of interest, enhancing Doppler detection.
Flex circuit design with hinged portions and openings
The flex circuit comprises first and second portions joined by hinges at opposite ends with openings between portions, enabling angular positioning of transducers mounted respectively on each portion.
Ramp integrated into housing for angular positioning
A ramp with sloped walls is coupled to the housing to position the transducers at predetermined angular positions proximate to the ramp wall, enhancing ultrasound beam direction toward vessels.
Method of assembling the ultrasound patch
Mounting transducers on flexible circuit portions joined proximate opposite ends, connecting electronics comprising transmit, receive, and processing circuitry, assembling the flex circuit in a frame holding transducers at fixed angular positions, and coupling the frame to a housing configured for patient skin contact.
Ultrasound patch assembly supporting transducers and electronics
An ultrasound patch with transducers connected to a flex circuit with air gaps and hinges, supported by a frame in defined angular positions, containing electronics positioned between transducers and an upper surface, enclosed in a housing with optional lens elements positioned over transducers.
The claims cover innovations in flexible and hinged transducer arrangements with air-backed elements, frames for angular positioning, integration of ramps and lenses, assembly methods, and complete ultrasound patch structures designed for continuous fluid flow sensing in vessels with improved patient comfort and signal detection.
Stated Advantages
Enables continuous or periodic ultrasound flow measurement hands-free, freeing caregiver hands for other tasks.
Air or foam-backed piezoelectric elements improve ultrasound transmission by limiting rearward transmission, increasing forward power.
Ramp and angled frame designs orient transducers at optimal Doppler angles (20-60 degrees) for better flow measurement.
Flexible phased array transducers conform to subject anatomy, providing comfort and the ability to steer ultrasound beams electronically.
Wide beam coverage via multiple transducer pairs ensures vessel intersection despite placement variations, allowing selection of best signal pairs.
Integration with ECG electrodes allows correlation of Doppler signals with cardiac events and measurement of left ventricular function markers.
Use of elastomeric patient pads with ramps and soft housings increases comfort for extended wear and facilitates placement near vessels like carotid artery and jugular vein.
Documented Applications
Continuous and non-invasive measurement of blood flow velocity in vessels, particularly for carotid artery and internal jugular vein in a patient.
Estimation and monitoring of central venous pressure (CVP) using Doppler power, jugular to carotid power ratio, and velocity time integrals over cardiac cycles.
Assessment and monitoring of congestive heart failure (CHF) via Doppler ejection time measurements and ECG correlation using wearable ultrasound patch.
Clinical diagnostics in hemodynamic pathologies such as sepsis, shock, heart failure through detection of flow changes and Doppler signals.
Use in compression garments for patients with circulatory dysfunction where flat transducers or phased arrays without pressure points are appropriate.
Application in wearable patient monitoring including long-duration use with straps securing the device on anatomy including neck, wrist, ankle, thigh, or knee.
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