Wearable Force Sensor and IMU for Hypertonus Quantification
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Solution Overview
Problem
Current methods for assessing spastic hypertonus in patients with neurologic injuries are inaccurate, lack granularity, and are resource-intensive, making them difficult to use in clinical settings, as they rely on subjective assessments and cumbersome devices that fail to accurately measure velocity-dependent resistance.
Innovation Solution
A wearable device combining force-sensing plates with an inertial measurement unit (IMU) to collect real-time force, position, and acceleration data during passive movement, allowing for the derivation of hypertonus measures such as catch positions and clonus magnitude, and correlating joint responses to clinical scales like the Modified Ashworth Scale and Tardieu Scale.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If clinicians use subjective assessment scales (Ashworth Scale, Modified Ashworth Scale) to rate spastic hypertonus, then the assessment can be performed quickly, but the measurement precision and reliability are poor
Solution Approach 1:
The patent replaces subjective mechanical assessment with objective sensor-based measurement. Force sensors and inertial measurement units (IMUs) automatically detect and quantify muscle resistance and movement characteristics, eliminating clinician subjectivity while maintaining quick assessment capability. The system computes hypertonus measures directly from sensor data without requiring clinician judgment.
Solution Approach 2:
The assessment system performs self-measurement through automated sensor detection. The force sensors and IMUs independently capture the mechanical properties of the limb without requiring clinician intervention for each measurement point, enabling rapid, repeatable assessments that are consistent across different evaluators.
2Measurement precision
If clinicians use the Tardieu Scale to assess spasticity, then measurement precision improves by capturing velocity-dependent resistance, but the device complexity and resource requirements increase
Solution Approach 1:
The patent combines force sensing and inertial measurement capabilities into a single integrated wearable device. The force sensors measure applied forces while IMUs simultaneously capture motion characteristics, enabling the system to automatically compute velocity-dependent resistance measures without requiring separate complex equipment for each measurement type.
Solution Approach 2:
The wearable device serves multiple functions: it measures force, detects motion, calculates velocity, and determines acceleration all through a single system. This multi-functional approach eliminates the need for separate specialized equipment for each measurement requirement, reducing overall device complexity while maintaining comprehensive assessment capability.
3Measurement precision
If advanced devices with EMG sensors, imaging techniques, or linear actuators are used, then measurement precision improves, but the device complexity and setup time increase
Solution Approach 1:
The patent extracts only the essential measurement capabilities needed for hypertonus assessment, eliminating unnecessary complex components. Instead of using full EMG systems, imaging equipment, or actuator arrays, the invention uses minimal force sensors and IMUs that directly measure the critical mechanical properties of spasticity, reducing complexity while maintaining sufficient precision.
Solution Approach 2:
The system employs simple, inexpensive force sensors and wearable IMUs that can be easily applied and removed without complex setup. These components are designed for clinical portability and rapid deployment, avoiding the need for expensive, bulky laboratory equipment while providing accurate measurement capability.
4Measurement precision
If bulky measurement devices are used, then measurement precision may improve, but ease of operation deteriorates due to difficulty in grasping and positioning
Solution Approach 1:
The force sensors and IMUs are integrated into a thin, flexible wearable device that conforms to the body segment being measured. This thin-film approach eliminates bulky casings while maintaining sensor functionality, allowing the device to be easily positioned on various body parts without requiring large access spaces or complex manipulation.
Solution Approach 2:
The wearable device is designed to be dynamic and adaptable to different body shapes and positions. The flexible construction allows the sensors to maintain proper contact and measurement capability regardless of the patient's limb position or body morphology, improving ease of operation across diverse clinical scenarios.
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 device provides a fast, accurate, and easy-to-use method for quantifying spastic hypertonus, improving intra-and inter-rater reliability and enabling precise assessment of spasticity severity, which can guide therapeutic strategies and track treatment progress.
Implementation Method 1
A wearable device combining force-sensing plates with an inertial measurement unit (IMU) to collect real-time force, position, and acceleration data during passive movement
Implementation Method 2
A wearable device combining force-sensing plates with an inertial measurement unit (IMU) to collect real-time force, position, and acceleration data during passive movement
Data Source
AI summary
A device for improved quantification of hypertonus is disclosed. The device is configured for grasping a limb segment of a patient and includes a force sensor module for continuously measuring a force generated by rotating the limb segment of the patient between a first position and a second position, at least one IMU, and at least one processor that generates at least one clinically relevant measure of response based at least on force data from the force sensor module and inertial data from the IMU.