Compact Hemodynamic Sensor with Compliant Interface for Tissue Protection
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Solution Overview
Problem
Current non-invasive blood pressure monitoring techniques are inadequate for continuous, accurate measurement, particularly in surgical settings, due to inaccuracies, tissue injury, and the lack of disposability and portability of components, as well as difficulties in maintaining consistent sensor positioning and correcting for hydrostatic pressure differences.
Innovation Solution
A compact, lightweight hemodynamic assessment apparatus featuring a U-shaped body with adjustable clamps and a pivot mechanism to securely position sensors on the wrist, allowing for continuous, non-invasive blood pressure monitoring with disposable components and wireless connectivity, enabling easy repositioning and calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rigid array of miniature pressure transducers is used to directly sense mechanical forces in the underlying subject tissue, then measurement precision is improved, but object-affected harmful factors worsen due to tissue injury and nerve damage
Solution Approach 1:
The patent introduces a compliant interface layer between the pressure transducer array and the subject tissue. This intermediary layer distributes the contact pressure more evenly across the tissue surface, preventing localized high-stress points that cause tissue injury and nerve damage, while still allowing accurate transmission of hemodynamic pressure signals to the transducers.
Solution Approach 2:
The patent employs a flexible, compliant housing or interface film that conforms to the contours of the subject's anatomy. This flexible structure distributes mechanical loads uniformly across the tissue, eliminating the harmful concentrated stresses associated with rigid transducer arrays, while maintaining intimate contact for accurate pressure sensing.
2Reliability
If an array of discrete transducers is used to ensure at least one transducer is always over the artery, then measurement reliability is improved, but device complexity worsens due to the need for multiple transducers and positioning mechanisms
Solution Approach 1:
The patent divides the sensing function into multiple discrete transducer elements arranged in an array. Each transducer covers a specific portion of the underlying artery, and collectively they ensure continuous coverage as the device moves or deforms. This segmentation allows reliable measurement without requiring complex active positioning mechanisms.
Solution Approach 2:
The compliant interface and flexible housing allow the transducer array to self-adjust and self-position relative to the artery as the subject moves or the device deforms. The passive mechanical properties of the interface enable the system to maintain optimal sensing contact without requiring active feedback control or complex positioning mechanisms.
3Ease of operation
If a standard inflatable arm cuff is used to occlude the subject's brachial artery, then ease of operation is improved, but measurement precision worsens because the techniques cannot replicate the subject's actual blood pressure waveform
Solution Approach 1:
The patent replaces the mechanical occlusion-based measurement system (inflatable cuff) with a direct pressure sensing system using transducer arrays that contact the tissue. This substitution eliminates the need for cyclic inflation and deflation, allowing continuous beat-to-beat measurement of the actual blood pressure waveform with higher fidelity.
Solution Approach 2:
The patent uses multiple transducers to capture and reconstruct the actual blood pressure waveform directly from the tissue, rather than inferring it from cuff pressure changes. This direct copying of the physiological signal provides accurate waveform replication without the limitations of occlusion-based methods.
4Ease of operation
If disposable components are implemented to improve ease of repair and reduce contamination risk, then ease of operation is improved, but loss of substance worsens due to single-use disposal
Solution Approach 1:
The patent divides the device into disposable sensor modules and reusable processing units. The disposable components contain only the transducer array and minimal associated electronics, while the expensive processing and control systems are reusable. This segmentation minimizes waste while maintaining the benefits of disposability for contamination-prone elements.
Solution Approach 2:
The patent enables easy replacement of disposable sensor modules while recovering and reusing the expensive processing electronics and control systems. This approach allows single-use of contamination-prone components while maintaining sustainability through recovery and reuse of valuable system elements.
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 apparatus provides accurate, continuous, and repeatable blood pressure monitoring with reduced tissue injury and increased portability, allowing for self-monitoring and maintenance, while addressing issues of disposability and hydrostatic pressure correction.
Implementation Method 1
at least one sensor adapted to generate a first signal relating to the pressure applied thereto
Data Source
AI summary
Improved apparatus and methods for non-invasively assessing one or more hemodynamic parameters associated with the circulatory system of a living organism. In one aspect, the invention comprises spatially compact “bracelet” embodiment adapted to accurately place and maintain a sensor (e.g., tonometric pressure sensor) with respect to the anatomy of the subject, including an optional alignment apparatus which moveably captures the sensor to, inter alia, facilitate coupling thereof to an actuator used to position the sensor during measurements. The alignment apparatus also advantageously allows the sensor position to be maintained when the fixture is removed from the subject, such as during patient transport. A completely autonomous variant of the bracelet apparatus having internal power supply and wireless interfaces is also disclosed. Methods for positioning the alignment apparatus and sensor and providing treatment to the subject are also described.