Photoacoustic Blood Pressure Sensing With Motion Feedback
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Solution Overview
Problem
Existing photoacoustic devices face challenges with low signal-to-noise ratio and alignment issues due to varying arterial orientations, leading to unreliable blood pressure measurements, especially when user movement occurs.
Innovation Solution
Incorporating a control system with inertial sensors and a light-steering system to adjust light direction based on motion detection, allowing for reliable blood pressure estimation by pausing or compensating for device movement and optimizing light alignment with multiple target areas using fewer light sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If motion detection and compensation mechanisms are added to photoacoustic devices, then measurement reliability during movement improves, but device complexity increases
Solution Approach 1:
The system uses motion detectors to continuously monitor device movement and feeds this information back to the control system, which then adjusts the light source positioning or pauses measurements accordingly. This closed-loop feedback mechanism maintains measurement reliability during user movement without requiring complex mechanical stabilization structures.
Solution Approach 2:
The patent introduces motion detectors and control systems as intermediary components between the user movement and the photoacoustic measurement process. These intermediaries detect motion and mediate the response by adjusting light source alignment or pausing measurements, preventing direct transmission of movement errors to the measurement system.
2Manufacturing precision
If light-steering devices are used to compensate for motion, then alignment precision improves, but device complexity and power consumption increase
Solution Approach 1:
The system employs adjustable light sources that can dynamically change their emission direction or position in response to detected motion. This dynamic adjustment capability allows the system to maintain optimal alignment with blood vessels despite device movement, achieving high alignment precision without fixed mechanical alignment structures.
Solution Approach 2:
The patent changes the operational parameters of the light sources by adjusting their emission angles, positions, or activation sequences based on motion detection data. This parameter adjustment allows the system to compensate for motion-induced misalignment while using the same physical light source components, avoiding the need for additional complex steering mechanisms.
3Adaptability or versatility
If multiple light sources are used to cover multiple target areas, then adaptability to varying arterial orientations improves, but device complexity and power consumption increase
Solution Approach 1:
The system divides the illumination task among multiple light sources, each responsible for illuminating specific target areas or angular sectors. This segmentation allows the system to adapt to different arterial orientations by activating only the relevant light sources, maintaining versatility while reducing the complexity of controlling all sources simultaneously.
Solution Approach 2:
The patent designs the light source system with multiple light-emitting elements that can collectively serve multiple functions: individual sources can target different arterial orientations, combine to provide broader illumination coverage, or work in sequence to reduce power consumption. This multi-functionality achieves adaptability without requiring specialized components for each scenario.
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
Enhances the reliability of blood pressure measurements by reducing noise and improving signal quality, while reducing complexity and power consumption compared to systems with arrays of light sources.
Implementation Method 1
an ultrasonic receiver system configured to receive ultrasonic waves generated by the target object responsive to the light from the light source system
Implementation Method 2
an ultrasonic receiver system configured to receive ultrasonic waves generated by the target object responsive to the light from the light source system and to generate ultrasonic receiver signals based, at least in part, on the ultrasonic waves generated by the target object
Data Source
AI summary
Some disclosed examples involve receiving ultrasonic receiver signals from an ultrasonic receiver system corresponding to ultrasonic waves generated by a target object responsive to light from a light source system, estimating one or more blood vessel features based, at least in part, on the ultrasonic receiver signals and estimating blood pressure based, at least in part, on the one or more blood vessel features. Some disclosed examples involve receiving inertial sensor data from an inertial sensor system, determining whether the inertial sensor data indicates apparatus motion that exceeds a threshold and controlling a photoacoustic plethysmography (PAPG) system that includes the light source system and the ultrasonic receiver system according to whether the apparatus motion exceeds the threshold.