A wristwatch-based wireless sensor platform for IoT health monitoring applications

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Kumar, Sanjeev
Buckley, John L.
Barton, John
Pigeon, Melusine
Newberry, Robert
Rodencal, Matthew
Hajzeraj, Adhurim
Hannon, Tim
Rogers, Ken
Casey, Declan
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A wristwatch-based wireless sensor platform for IoT wearable health monitoring applications is presented. The paper describes the platform in detail, with a particular focus given to the design of a novel and compact wireless sub-system for 868 MHz wristwatch applications. An example application using the developed platform is discussed for arterial oxygen saturation (SpO2) and heart rate measurement using optical photoplethysmography (PPG). A comparison of the wireless performance in the 868 MHz and the 2.45 GHz bands is performed. Another contribution of this work is the development of a highly integrated 868 MHz antenna. The antenna structure is printed on the surface of a wristwatch enclosure using laser direct structuring (LDS) technology. At 868 MHz, a low specific absorption rate (SAR) of less than 0.1% of the maximum permissible limit in the simulation is demonstrated. The measured on-body prototype antenna exhibits a −10 dB impedance bandwidth of 36 MHz, a peak realized gain of −4.86 dBi and a radiation efficiency of 14.53% at 868 MHz. To evaluate the performance of the developed 868 MHz sensor platform, the wireless communication range measurements are performed in an indoor environment and compared with a commercial Bluetooth wristwatch device.
IoT , Wearables , Sub-GHz , Electrically small antennas , LDS , Wristwatch antenna , Bandwidth enhancement , Healthcare , PPG , Wireless sensor
Kumar, S., Buckley, J. L., Barton, J., Pigeon, M., Newberry, R., Rodencal, M., Hajzeraj, A., Hannon, T., Rogers, K., Casey, D., O'Sullivan, D. and O'Flynn, B. (2020) 'A Wristwatch-Based Wireless Sensor Platform for IoT Health Monitoring Applications', Sensors, 20(6), 1675, (25 pp.), doi: 10.3390/s20061675