Skin-mounted soft electronics that incorporate high-bandwidth triaxial accelerometers can capture broad classes of physiologically relevant information, including mechano-acoustic signatures of underlying body processes (such as those measured by a stethoscope) and precision kinematics of core-body motions. Here, we describe a wireless device designed to be conformally placed on the suprasternal notch for the continuous measurement of mechano-acoustic signals, from subtle vibrations of the skin at accelerations of around 10−3 m s−2 to large motions of the entire body at about 10 m s−2, and at frequencies up to around 800 Hz. Because the measurements are a complex superposition of signals that arise from locomotion, body orientation, swallowing, respiration, cardiac activity, vocal-fold vibrations and other sources, we exploited frequency-domain analysis and machine learning to obtain—from human subjects during natural daily activities and exercise—real-time recordings of heart rate, respiration rate, energy intensity and other essential vital signs, as well as talking time and cadence, swallow counts and patterns, and other unconventional biomarkers. We also used the device in sleep laboratories and validated the measurements using polysomnography.
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The codes used for the embedded system and data collection are available on GitHub at https://github.com/johnrogersgroup/Wireless_MA. The analysis codes used in this study are available from the authors upon request.
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The materials and device-engineering aspects of the research were supported by the Material Science and Engineering Department and Center for Bio-Integrated Electronics at Northwestern University. K.L. acknowledges support from the Samsung Scholarship. K.L. acknowledges the help from A. Sahakian on radio frequency communication and antenna tuning. Z.X. acknowledges support from the National Natural Science Foundation of China (grant no.11402134). S.X. and J.A.R. recognizes support from the National Institute on Aging of the National Institutes of Health under R41AG062023 and R43AG060812. R.A. acknowledges support from National Science Foundation (NSF) Graduate Research Fellowship under grant no. 1842165 and the Ford Foundation Predoctoral Fellowship. Y.H. acknowledges support from the NSF (CMMI1635443). S.M. is grateful to Indo-U.S. Science and Technology Forum (SERB-IUSSTF) for her SERB Indo-U.S. Postdoctoral Award. X.N. thanks D. Lu for helpful discussions. K.L. thanks the Dion family for volunteering for the data collection.
The authors declare no competing interests.
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Lee, K., Ni, X., Lee, J.Y. et al. Mechano-acoustic sensing of physiological processes and body motions via a soft wireless device placed at the suprasternal notch. Nat Biomed Eng (2019). https://doi.org/10.1038/s41551-019-0480-6