Development and Bench-to-Human Feasibility Evaluation of a Wireless Pinch-and-Grip Dynamometer

Objective: This study presents MeRKeL, a portable wireless system designed for quantitative, reference-calibrated assessment of pinch and grip strength, and evaluates its technical validity and human feasibility under standardized laboratory conditions.Methods: The system consists of two compact and functionally aligned modules (pinch and grip dynamometer) sharing a unified electronic architecture and data acquisition pipeline. Both employ task-specific mechanical designs tailored to the distinct loading characteristics of pinch and grip actions. Reference-based calibration and bench validation were performed across the full operating ranges and across multiple units. Accuracy, agreement, and within-session repeatability were evaluated using root mean squared error (RMSE), Bland–Altman analysis, and intraclass correlation coefficient (ICC). Feasibility testing in 196 healthy adults examined associations between maximal strength and demographic, behavioral, and health-related variables.Results: Bench validation showed high agreement with the calibrated reference instrument (pinch: RMSE = 0.95 N, bias $= -0.56$ N; grip: RMSE = 1.86 N, bias $= -1.10$ N), and within-session repeatability was excellent (MDC95 pinch = 0.86 N; grip = 1.43 N). Experimental testing reproduced expected associations with key demographic and behavioral factors.Conclusion: The MeRKeL system enables accurate and repeatable, reference-calibrated wireless measurement of pinch and grip strength, establishing a robust technical foundation for subsequent clinical evaluation and future home-based neuromuscular monitoring studies.