{"doi":"10.3390/s21041502","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","abstract":"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 \"Manumeter\"). The \"HAND\" (Hand Activity estimated by Nonlinear Detection) algorithm assigns a \"HAND count\" 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' 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.","journal":"Sensors","year":2021,"id":164102,"datarank":0.5533319181170905,"base_score":3.6888794541139363,"endowment":3.6888794541139363,"self_citation_contribution":0.5533319181170905,"citation_network_contribution":0.0,"self_endowment_contribution":0.5533319181170905,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":39,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9573,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2021-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":685731,"name":"Justin B. Rowe","orcid":null,"position":1,"is_corresponding":false},{"id":684873,"name":"Vicky Chan","orcid":"0000-0003-2791-9001","position":2,"is_corresponding":false},{"id":413768,"name":"David J. Reinkensmeyer","orcid":"0000-0002-3196-8706","position":3,"is_corresponding":false},{"id":685730,"name":"Diogo Schwerz de Lucena","orcid":null,"position":0,"is_corresponding":true}],"reference_count":32,"raw_metadata":{"citation_network_status":"fetched"},"created_at":"2026-07-18T23:45:27.031465Z","pmid":"33671505","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}