Low-Complexity Design and Validation of Wireless Motion Sensor Node to Support Physiotherapy

• Main Authors: Jona Cappelle, Laura Monteyne, Jarne Van Mulders, Sarah Goossens, Maarten Vergauwen, Liesbet Van der Perre
• Format: Article
• Language: English
• Published: MDPI AG 2020-11-01
• Series: Sensors
• Subjects: physiotherapy; e-health; motion sensing; wireless charging; wireless connectivity; low power
• Online Access: https://www.mdpi.com/1424-8220/20/21/6362

We present a motion sensor node to support physiotherapy, based on an *imu. The node has wireless interfaces for both data exchange and charging, and is built based on commodity components. It hence provides an affordable solution with a low threshold to technology adoption. We share the hardware design and explain the calibration and validation procedures. The sensor node has an autonomy of 28 h in operation and a standby time of 8 months. On-device sensor fusion yields static results of on average <inline-formula><math display="inline"><semantics><mrow><mn>3</mn><mo>.</mo><mn>28</mn></mrow></semantics></math></inline-formula><inline-formula><math display="inline"><semantics><msup><mrow></mrow><mo>∘</mo></msup></semantics></math></inline-formula> with a drift of 2<inline-formula><math display="inline"><semantics><msup><mrow></mrow><mo>∘</mo></msup></semantics></math></inline-formula> per half hour. The final prototype weighs 38 g and measures 6 cm ×<inline-formula><math display="inline"><semantics><mrow><mn>1</mn><mo>.</mo><mn>5</mn></mrow></semantics></math></inline-formula> cm. The resulting motion sensor node presents an easy to use device for both live monitoring of movements as well as interpreting the data afterward. It opens opportunities to support and follow up treatment in medical cabinets as well as remotely.