Wearable Leg Circumference Sensor for Edema Monitoring
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Solution Overview
Problem
Current methods for monitoring edema in patients with congestive heart failure are cumbersome, lead to low patient compliance, and provide inaccurate measurements, lacking an automated system for calculating leg circumference and estimating volume.
Innovation Solution
A wearable device that fits around the leg like a sock, using stretchable wires with increasing electrical resistance proportional to length, to automatically measure circumference and calculate volume, transmitting data via Bluetooth to a remote device for monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional methods (tape measure or water displacement) are used to monitor leg volume, then measurement capability is provided, but device complexity and ease of operation deteriorate due to cumbersome procedures
Solution Approach 1:
The patent replaces manual mechanical measurement methods (tape measure wrapping, water displacement buckets) with an electronic sensor system that automatically measures leg circumference. The sensor device includes stretchable wires with resistive elements that detect circumference changes through electrical resistance variations, eliminating the need for manual measurement operations.
Solution Approach 2:
The measurement system performs self-service by automatically calculating leg volume from circumference measurements without requiring patient involvement in the calculation process. The device autonomously monitors circumference at multiple points, processes the data through algorithms, and generates volume estimates, allowing patients to simply wear the device while it performs the monitoring function.
2Measurement precision
If manual measurement methods are used, then some measurement capability is achieved, but measurement precision deteriorates due to inaccurate results
Solution Approach 1:
The patent divides the leg into multiple measurement segments by placing sensors at different circumferential locations (e.g., ankle, calf, thigh). Each sensor independently measures circumference at its specific location, and the system integrates these segmented measurements to calculate total leg volume, improving precision through multiple data points rather than a single measurement.
Solution Approach 2:
The system transitions from one-dimensional linear measurements (single circumference) to three-dimensional volume estimation by measuring circumference at multiple vertical positions along the leg. This dimensional expansion allows calculation of leg volume as a series of stacked cylindrical segments, significantly improving measurement precision.
3Productivity
If automated measurement is implemented, then productivity and compliance improve, but device complexity increases
Solution Approach 1:
The sensor device performs multiple functions within a single integrated system: it measures circumference at multiple locations, transmits data wirelessly, stores measurements in memory, and interfaces with external devices for analysis. This multi-functionality consolidates what would otherwise require multiple separate devices into one universal monitoring system.
Solution Approach 2:
The patent uses stretchable wires embedded in a flexible sock-like structure that conforms to the leg's shape. This flexible implementation allows the electronic sensing elements to be integrated into a wearable garment without rigid components, reducing perceived device complexity while maintaining automated measurement capabilities.
4Reliability
If frequent monitoring is performed, then measurement completeness improves, but loss of time and patient burden increase
Solution Approach 1:
The automated sensor device enables continuous monitoring of leg circumference throughout the day as the patient wears it during normal activities. The system continuously records circumference data at multiple positions, providing uninterrupted measurement coverage that captures fluid accumulation trends over time without requiring the patient to stop activities for manual measurements.
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, user-friendly, and continuous monitoring of leg volume changes, improving patient compliance and allowing for timely adjustments in diuretic dosages, with the ability to detect fluid retention and edema severity.
Implementation Method 1
stretchable wires with increasing electrical resistance proportional to length
Data Source
AI summary
A device monitors circumferences of the leg, and estimates volume of a section of the leg, to detect edema, which can be indicative of CHF, and gauge the effectiveness of medication. The device sends the calculations to a database via BLUETOOTH™ for the patient's treating medical personnel to see.