Finger Pad Bladder Layout for Low-Noise Blood Pressure Sensing

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Solution Overview

Problem

Existing blood pressure measurement systems using inflatable measurement bladders that fully surround and compress the finger are inaccurate and require electromagnetic radiation for measurement, leading to noise and artifacts in the oscillometric signal.

Innovation Solution

A vital sign measuring device (VSMD) with an arcuate inflatable bladder that contacts only a portion of the finger, combined with a structure or implement (SOI) to urge the finger pad against the bladder, enhancing contact and reducing movement, uses oscillometric signals for accurate blood pressure measurement without electromagnetic radiation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If an inflatable measurement bladder fully surrounds and compresses the finger, then the measurement system can be simplified, but the measurement accuracy decreases and electromagnetic radiation is required

Engineering Contradiction:

Improvemeasurement system complexityVSAvoidblood pressure measurement accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The measurement system is segmented into two separate components: an inflatable bladder that contacts only the bottom portion of the finger, and a separate structure or implement (SOI) that applies force to the top of the finger. This segmentation allows the bladder to be simpler while the SOI provides the additional functionality of force application, resolving the contradiction between device simplicity and measurement accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of having the bladder contact the entire finger periphery as in conventional systems, the invention inverts the approach by having the bladder contact only the bottom portion of the finger, while a separate SOI applies force to the top. This inversion allows for improved measurement accuracy without requiring the bladder to fully surround the finger.

Inventive Principle:

Principle #13The other way round (Inversion)

2Device complexity

If an inflatable measurement bladder fully contacts and compresses the finger periphery, then the device structure is simplified, but noise and artifacts increase in the oscillometric signal

Engineering Contradiction:

Improvebladder configuration simplicityVSAvoidnoise and artifacts in oscillometric signal

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The measurement system is divided into two separate components: the inflatable bladder contacting only the bottom finger portion, and a separate SOI applying force to the top. This segmentation reduces the bladder's contact area, thereby reducing noise and artifacts in the oscillometric signal while maintaining measurement capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The bladder is configured to contact only specific local regions (bottom portion) of the finger rather than the entire periphery. This local quality approach concentrates the measurement function in a specific area, reducing unwanted contact and associated noise while the SOI provides force application from a different location.

Inventive Principle:

Principle #3Local quality

3Object-affected harmful factors

If the bladder contacts only a portion of the finger, then noise is reduced, but insufficient contact force is applied without additional structures

Engineering Contradiction:

Improvenoise in oscillometric signalVSAvoidcontact force on finger

Core Design Contradiction:

Object-affected harmful factorsVSForce

Solution Approach 1:

The force application function is separated from the bladder and assigned to a dedicated SOI. The bladder provides localized contact force to the bottom finger portion, while the SOI applies additional force to the top, ensuring sufficient total contact force is applied without requiring the bladder to contact the entire finger.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The SOI acts as an intermediary structure that applies force to the finger top, complementing the bladder's force application to the finger bottom. This intermediary component ensures sufficient total contact force is achieved while maintaining the benefit of reduced bladder contact area and associated noise.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution significantly increases the amplitude of the oscillometric signal, reduces noise, and improves the signal-to-noise ratio, resulting in more accurate and repeatable systolic and diastolic blood pressure measurements.

Implementation Method 1

uses oscillometric signals for accurate blood pressure measurement

Methodology Applied

Scientific EffectOscillometric method:

Data Source

PatentUS12495977B2Apparatus and methods for measuring blood pressure and other vital signs via a finger

Publication Date: 2025.12.16 ARC DEVICES LTD

AI summary

There is disclosed a vital sign measuring device and method for obtaining an indication of a person's blood pressure via the person's finger by means of an inflatable measurement bladder adapted to contact only a portion of an underside of a finger defining a finger pad. A structure or other implement applies a downward force on a top portion of the finger opposite the finger pad. Blood pressure may be determined without the use of any electromagnetic radiation, such as miniature dynamic light sensing (mDLS). Apparatuses and methods for obtaining an indication of other vital signs, including hematocrit and total protein, are also disclosed.