Deformable Sensors for Pressure and Position Assessment Using Time-Domain Reflectometry in Motor Rehabilitation

Area of Science:

• Biomedical Engineering
• Sensor Technology
• Rehabilitation Science

Background:

• Monitoring patient interactions is crucial for effective motor rehabilitation.
• Existing sensors may lack the adaptability and spatial resolution required for diverse rehabilitation tasks.
• Deformable sensors offer potential for unobtrusive and context-aware interaction monitoring.

Purpose of the Study:

• To design and validate deformable sensors utilizing time-domain reflectometry (TDR) for rehabilitation interaction monitoring.
• To investigate different sensor architectures for suitability in various rehabilitation scenarios.
• To establish the relationship between sensor response and physical interaction parameters like depth and location.

Main Methods:

• Three deformable sensor architectures were designed: planar multilayer, coaxial foam, and coaxial TPU-Hilbert.
• Controlled indentation tests were conducted to analyze sensor responses.
• Two TDR-derived features, minimum reflection coefficient (ρmin) and perturbation time (tpert), were extracted.
• Calibration curves and 2D maps were generated to analyze sensor performance.
• Application-oriented manual tests assessed suitability for different grasp types.

Main Results:

• TDR-derived features (ρmin and tpert) correlated with deformation intensity and contact localization.
• Sensor performance varied across the three geometries, indicating suitability for specific rehabilitation tasks.
• Planar and coaxial sensors demonstrated adaptability for localized pressing, grasping, and squeezing.
• Preliminary calibration and mapping provided insights into position and depth dependence.

Conclusions:

• Time-domain reflectometry (TDR)-based deformable sensors are viable for spatially resolved monitoring of motor rehabilitation interactions.
• These sensors are low-complexity and geometry-adaptable, making them suitable for diverse rehabilitation applications.
• The findings support the use of TDR sensors for objective and detailed assessment of patient motor function during rehabilitation.