Wearable CRT Measurement Using Optical and Force Sensing
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Solution Overview
Problem
Existing devices for measuring capillary refill time (CRT) are overly complex and lack a mechanism to accurately link force application and release to the timing of CRT, making them unsuitable for low-cost, disposable sensors or in-home use, and manual pressure application is often inaccurate.
Innovation Solution
A device that combines an optical signal with a force signal to determine CRT, ensuring acceptable force magnitude and duration, and includes mechanisms to accommodate various finger sizes, with algorithms to adjust for measurement reliability and integrate with other vital signs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing CRT measurement devices are used, then CRT measurement capability is provided, but device complexity increases and cost increases
Solution Approach 1:
The patent combines the force sensor, optical sensor, and processor into a single integrated wearable device unit that fits on the patient's digit. This merging of previously separate components (force application mechanism, optical detection system, and control electronics) into one compact device reduces overall system complexity while maintaining full CRT measurement functionality.
Solution Approach 2:
The wearable device performs multiple functions: it applies controlled force to the digit, detects optical changes in the nail bed, timestamps the force release event, and processes CRT data. This multi-functional design eliminates the need for separate devices for each function, reducing complexity and enabling low-cost disposable sensor implementations.
2Reliability
If existing CRT measurement devices are used, then CRT measurement is possible, but cost increases and usability decreases
Solution Approach 1:
The patent enables the creation of low-cost, disposable sensors that can be used for CRT measurement and then discarded. This is achieved by using inexpensive force sensors, optical sensors, and integrated circuits that can be manufactured at low cost, making the device suitable for single-use applications in hospital settings without requiring expensive reusable components.
Solution Approach 2:
The device automatically applies force to the digit, detects the force release event, timestamps it, and measures CRT without requiring manual operation. This self-service capability eliminates the need for trained operators and simplifies the measurement process, improving usability while reducing costs associated with manual measurement techniques.
3Ease of operation
If manual pressure application is used, then simplicity is maintained, but measurement accuracy decreases
Solution Approach 1:
The force sensor provides real-time feedback on the force applied to the digit, allowing the device to maintain consistent force levels and accurately detect when force is released. This feedback mechanism ensures that the blanching force is sufficient to achieve complete blanching and that the release timing is precise, significantly improving measurement accuracy over manual techniques.
Solution Approach 2:
The patent replaces manual mechanical pressure application with an automated force application system using a force sensor and controlled actuation mechanism. This substitution eliminates the variability and imprecision of manual pressure application while maintaining simplicity through automation, achieving both ease of operation and high measurement precision.
4Device complexity
If force sensor is not included, then device complexity is reduced, but ability to link force release to CRT timing is lost
Solution Approach 1:
The force sensor acts as an intermediary between the force application mechanism and the CRT measurement system. It provides precise detection of the force release event, which serves as the timing reference for starting the CRT measurement. This intermediary component enables accurate synchronization between force release and optical detection, achieving high CRT timing precision.
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
Provides a reliable, digital measure of CRT, suitable for in-home use and hospital settings, improving accuracy and usability by ensuring consistent force application and release, and integrating with other vital signs for comprehensive patient assessment.
Implementation Method 1
an optical signal associated with light that has been reflected from a capillary bed
Data Source
AI summary
An example device for measuring a digital capillary refill time (CRT) can include a wearable component, a processor, and an output. The wearable component includes a touch pressure element and an optical sensor capable of transmitting and detecting optical energy. The detector converts the received optical energy into an electrical signal that represents the optical energy incident on the optical detector. The processor is programmed to receive the electrical signal from the detector, determine the CRT based on the optical sensor data, and output the electrical signal or the determined CRT.