Motion-tolerant magnetic earring sensor and wireless earpiece for wearable photoplethysmography

  • Authors:

  • Ming-Zher Poh;Nicholas C. Swenson;Rosalind W. Picard

  • Affiliations:

  • Harvard-MIT Division of Health Sciences and Technology and Media Laboratory, Massachusetts Institute of Technology, Cambridge, MA;Media Laboratory, Massachusetts Institute of Technology, Cambridge, MA;Media Laboratory, Massachusetts Institute of Technology, Cambridge, MA

  • Venue:
  • IEEE Transactions on Information Technology in Biomedicine - Special section on new and emerging technologies in bioinformatics and bioengineering
  • Year:
  • 2010

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Abstract

This paper addresses the design considerations and critical evaluation of a novel embodiment for wearable photo-plethysmography (PPG) comprising a magnetic earring sensor and wireless earpiece. The miniaturized sensor can be worn comfortably on the earlobe and contains an embedded accelerometer to providemotion reference for adaptive noise cancellation. The compact wireless earpiece provides analog signal conditioning and acts as a data-forwarding device via a radio frequency transceiver. Using Bland-Altman and correlation analysis, we evaluated the performance of the proposed system against an FDA-approved ECG measurement device during daily activities. The mean ± standard deviation (SD) of the differences between heart rate measurements from the proposed device and ECG (expressed as percentage of the average between the two techniques) along with the 95% limits of agreement (LOA = ±1.96 SD) was 0.62% ± 4.51% (LOA = -8.23% and 9.46%), -0.49% ± 8.65% (-17.39% and 16.42%), and -0.32% ± 10.63% (-21.15% and 20.52%) during standing, walking, and running, respectively. Linear regression indicated a high correlation between the two measurements across the three evaluated conditions (r = 0.97, 0.82, and 0.76, respectively with p