Design of a Modular Multi-Finger Grip-Force Measurement System for Post-Stroke Hand Function Assessment
Design, Implementation, and Prototype Validation
J.R. van Aernsbergen (TU Delft - Mechanical Engineering)
A.H.A. Stienen – Mentor (TU Delft - Biomechatronics & Human-Machine Control)
J.C. van Zanten – Mentor (TU Delft - Biomechatronics & Human-Machine Control)
F.C.T. van der Helm – Graduation committee member (TU Delft - Biomechatronics & Human-Machine Control)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
Background and Objective— Accurate measurement of individual finger forces is essential for assessing hand function and understanding motor impairments, yet conventional tools such as dynamometers measure only total grip strength and offer no insight into finger-specific contributions. This thesis addresses this gap by designing and validating a modular measurement system capable of measuring forces from all five digits across three predefined grasp types, operable by post-stroke patients and compatible with integration into perturbation platforms such as the Shoulder–Elbow Perturbator (SEP).
Methods and Results— An iterative Design Thinking approach guided the development of a modular hand-function assessment device featuring interchangeable grasp interfaces with spring-guided pistons to enable natural grasp motion while capturing individual finger forces. Sensor calibration using standardized weight steps showed excellent linearity, with an average calibration error of 0.15 N, substantially outperforming the 1.25 N error specified by the manufacturer. Validation with thirteen healthy participants demonstrated high repeatability across all grasp types, with SD, CV, and RMSE values comparable to a reference dynamometer. The device further reproduced expected biomechanical force-distribution patterns, including the characteristic flattening of finger contributions in larger cylindrical grasps.
Conclusion— The results demonstrate the feasibility of a practical, compact, and modular multi-finger force measurement system capable of detailed hand-function assessment. With refinement of mechanical tolerances and subsequent clinical validation, the device has strong potential for both rehabilitation assessment and integration into perturbation-based motor-control research, providing a more complete understanding of individual finger contributions during functional grasping.