{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,26]],"date-time":"2026-02-26T05:08:45Z","timestamp":1772082525051,"version":"3.50.1"},"reference-count":30,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2021,2,22]],"date-time":"2021-02-22T00:00:00Z","timestamp":1613952000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["R44HD086953"],"award-info":[{"award-number":["R44HD086953"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["R01HD062744"],"award-info":[{"award-number":["R01HD062744"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>There are few wearable sensors suitable for daily monitoring of wrist and finger movements for hand-related healthcare applications. Here, we describe the development and validation of a novel algorithm for magnetically counting hand movements. We implemented the algorithm on a wristband that senses magnetic field changes produced by movement of a magnetic ring worn on the finger (the \u201cManumeter\u201d). The \u201cHAND\u201d (Hand Activity estimated by Nonlinear Detection) algorithm assigns a \u201cHAND count\u201d by thresholding the real-time change in magnetic field created by wrist and\/or finger movement. We optimized thresholds to achieve a HAND count accuracy of ~85% without requiring subject-specific calibration. Then, we validated the algorithm in a dexterity-impaired population by showing that HAND counts strongly correlate with clinical assessments of upper extremity (UE) function after stroke. Finally, we used HAND counts to test a recent hypothesis in stroke rehabilitation that real-world UE hand use increases only for stroke survivors who achieve a threshold level of UE functional capability. For 29 stroke survivors, HAND counts measured at home did not increase until the participants\u2019 Box and Blocks Test scores exceeded ~50% normal. These results show that a threshold-based magnetometry approach can non-obtrusively quantify hand movements without calibration and also verify a key concept of real-world hand use after stroke.<\/jats:p>","DOI":"10.3390\/s21041502","type":"journal-article","created":{"date-parts":[[2021,2,22]],"date-time":"2021-02-22T20:42:51Z","timestamp":1614026571000},"page":"1502","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":35,"title":["Magnetically Counting Hand Movements: Validation of a Calibration-Free Algorithm and Application to Testing the Threshold Hypothesis of Real-World Hand Use after Stroke"],"prefix":"10.3390","volume":"21","author":[{"given":"Diogo","family":"Schwerz de Lucena","sequence":"first","affiliation":[{"name":"John A Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA"},{"name":"CAPES Foundation, Ministry of Education of Brazil, Brasilia 70040-020, Brazil"}]},{"given":"Justin","family":"Rowe","sequence":"additional","affiliation":[{"name":"Flint Rehabilitation Devices, Irvine, CA 92614, USA"}]},{"given":"Vicky","family":"Chan","sequence":"additional","affiliation":[{"name":"Department of Mechanical and Aerospace Engineering, Department of Anatomy and Neurobiology, University of California Irvine, Irvine, CA 92697, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3196-8706","authenticated-orcid":false,"given":"David","family":"Reinkensmeyer","sequence":"additional","affiliation":[{"name":"Department of Mechanical and Aerospace Engineering, Department of Anatomy and Neurobiology, University of California Irvine, Irvine, CA 92697, USA"}]}],"member":"1968","published-online":{"date-parts":[[2021,2,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"21","DOI":"10.1186\/1743-0003-9-21","article-title":"A review of wearable sensors and systems with application in rehabilitation","volume":"9","author":"Patel","year":"2012","journal-title":"J. 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