Finger Assist Tool Structure for Accurate Capillary Refill Sensing
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Solution Overview
Problem
Existing methods for measuring capillary refill time, such as manually pressing on a biological tissue and visually checking color change, lack quantitativeness and are prone to measurement errors due to finger size variations affecting the alignment of sensors.
Innovation Solution
An assist tool with a support body, bag body, and spacers is designed to align the finger's nail center with the sensor's center, ensuring stable pressure application and release by using a fluid passage and physiological information detector between the finger and bag body, with spacers preventing finger interference at the hinge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the assist tool is designed without a spacer, then the device complexity is reduced, but the alignment precision between the bag body and the nail center deteriorates
Solution Approach 1:
A spacer is introduced as an intermediary component between the support body and the bag body. This spacer serves as a positioning element that ensures the bag body is correctly aligned with the nail center when the finger is inserted. The spacer acts as a mediator that translates the general insertion action into precise alignment, solving the contradiction by adding a simple structural element that enables accurate positioning without complex mechanisms.
2Volume of moving object
If the finger tip is placed near the hinge for compact design, then the device compactness is improved, but the measurement precision deteriorates due to deviation from nail center
Solution Approach 1:
The spacer serves as a positioning intermediary that decouples the hinge location from the nail center alignment requirement. By placing the spacer at a specific position relative to the hinge and designing it with appropriate dimensions, the system allows the finger tip to be near the hinge for compactness while the spacer ensures the bag body remains aligned with the nail center, thus maintaining measurement precision.
Solution Approach 2:
The spacer is pre-positioned in the support body at a location that anticipates the finger insertion. This preliminary positioning ensures that when the finger is inserted, the spacer automatically guides the finger to the correct position, preventing deviation from the nail center even when the finger tip is near the hinge. This preliminary action eliminates the need for complex alignment procedures during measurement.
3Device complexity
If manual pressure application is used, then the device complexity is reduced, but the measurement reliability deteriorates due to operator variability
Solution Approach 1:
The assist tool is designed to apply pressure automatically through the bag body when the finger is inserted and the system is activated. The spacer ensures proper positioning, and the system self-regulates the pressure application process, eliminating the need for manual pressure control by the operator. This self-service mechanism ensures consistent, repeatable pressure application that improves measurement reliability while keeping the operation simple.
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
Enables accurate and stable measurement of capillary refill time and other physiological parameters like SpO2 by aligning the nail center with the sensor's center, reducing measurement errors and improving attachment comfort.
Implementation Method 1
a light emitter is placed on one of a pad side and a nail side, and a light detector is placed on the other side. Capillary refill time is specified from a change in a detected light intensity of the light detector
Data Source
AI summary
An assist tool to be attached to a finger of a subject. The assist tool includes a support body placed on a first side of the finger in a case where the support body is attached to the finger, a bag body configured to be placed on a second side, the second side being opposite to the first side of the finger with respect to the finger, and a fluid passage communicating with inside of the bag body. A physiological information detector for obtaining the physiological information is configured to be placed between the finger and the support body, and between the finger and the bag body. A spacer is provided in the support body such that the finger does not enter a fingertip side of the bag body.