Benchtop validation of a low-cost wearable triaxial accelerometer

Clinical Snapshot

Key Findings

• P Value: Not reported

• Effect Size: RMSE values were highly similar between x (mediolateral) and y (vertical) axes (<3.2% difference between SUT and RS); z-axis (anteroposterior) showed moderately larger errors (~9% difference). Bland-Altman analysis confirmed minimal bias and narrow limits of agreement for x and y axes; greater variability on z-axis with no evidence of substantial systematic deviation. Near-unity correlations across all axes.

• Primary Outcome: Concurrent validity of the low-cost SUT triaxial accelerometer compared with the Physilog®5 reference sensor across three axes under controlled benchtop conditions

• Nnt Or Sensitivity: Sensitivity and specificity not applicable to this measurement agreement study. Key agreement metrics: RMSE <3.2% difference (x, y axes); ~9% difference (z-axis); MAE similar for x and y axes, slightly higher for z-axis; Bland-Altman bias described as minimal for x and y, greater variability for z

• Confidence Interval: Not explicitly reported in the abstract for bias estimates; Bland-Altman limits of agreement serve as the primary precision metric

Clinical Application

The device's low cost (~USD 60 versus >USD 1,000 for the Physilog®5) represents a significant advantage for scalable deployment in community health programs, low-resource settings, and large-scale research studies. However, feasibility in clinical practice requires demonstration of real-world validity, user acceptability, data transmission reliability, and integration with clinical workflows — none of which have been assessed. Falls prevention is a national health priority in Australia, with the RACGP and the Australian Commission on Safety and Quality in Health Care (ACSQHC) recommending multifactorial falls risk assessment for older adults. Wearable accelerometers have potential utility within community-based falls prevention programs and residential aged care settings. However, the TGA would require clinical-grade validation data before any such device could be marketed as a medical device for fall detection in Australia. The PBS does not currently subsidise wearable fall-detection technology. This device remains at a pre-clinical validation stage and is not ready for TGA submission or clinical deployment. Future studies should include Australian community-dwelling older adults to assess real-world performance in this population. At this stage, applicable only to laboratory or research settings requiring low-cost triaxial accelerometry under controlled conditions. The intended clinical population — older adults at risk of falls requiring ambulatory monitoring — has not been studied. Clinicians should not yet deploy this device for individual patient fall-risk assessment.

Abstract

Wearable inertial sensors have become a cornerstone technology for detecting fall-related events, such as tripping while walking, in older adults. However, low-cost devices must undergo rigorous validation to ensure fidelity and stability in measurement. This study aimed to evaluate the concurrent validity of a newly developed, low-cost triaxial accelerometer by comparing its linear acceleration measurements with those obtained from a widely used commercial reference sensor (RS). A methodological validation study was conducted to assess the accuracy and precision of the proposed accelerometer. Triaxial linear acceleration data were simultaneously collected from the new device (sensor under test, SUT) and a commercial RS (Physilog®5, GaitUp, Lausanne, Switzerland). Measurements were obtained across three independent axes from 49 SUT units, with three repeated trials performed for each axis. The RS exhibited a more negative mean bias on the mediolateral (x) axis and a slightly larger mean bias on the vertical (y) axis. The SUT showed a greater mean bias (offset) on the anteroposterior (z) axis. Root mean squared error values were highly similar between thexandyaxes (<3.2% difference), while thez-axis presented moderately larger errors (∼9%). Mean absolute error was similar in thexandyaxes, whereas thez-axis was slightly higher. Visual waveform comparisons demonstrated strong overlap in mean time-series profiles, and near-unity correlations indicated high correspondence in signal variation. Bland-Altman analysis confirmed minimal bias and narrow limits of agreement for thexandyaxes, with greater variability observed along thezaxis, but no evidence of substantial systematic deviation. Overall, the low-cost accelerometer (∼60 USD) showed strong agreement with the commercial reference device (>1 000 USD), supporting its validity for three-dimensional linear acceleration measurement under controlled laboratory conditions. This low-cost device represents a promising solution for scalable motion monitoring and fall-related event detection.

References

1. 1.Silva, C. F. E., Leal, I. D. S., de Melo, P. R. V., Silva, M. A., Caldas, R. R., Buarque, F., & Trombini-Souza, F. (2026). Benchtop validation of a low-cost wearable triaxial accelerometer. Biomedical Physics & Engineering Express. https://doi.org/10.1088/2057-1976/ae866e