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flow during running or other activities with
significant motion. We may also even be able to
eliminate the shearing noise at the earlobe, by
filtering it from blood flow signals using a FFT.
Figure 11: Schematic of blood flow measurement when a
shearing occurs.
In conclusion, we have succeeded in stably
measuring blood flow during running using the
MEMS blood flow sensor. The device also captures
the noise caused by running motion; however, we
can eliminate this and obtain the heart rate by
performing a FFT on blood flow power spectra,
cancelling out the steady rhythm of the pace, and
observing for an incremental frequency shift in the
spectrum peak that corresponds to heart rate. The
MEMS blood flow sensor would contribute to
researches in areas like sports science or health
science. Moreover, we found that the extent of the
observed changes to blood flow depend on the
intensity of exercise. These results suggest that the
MEMS blood flow sensor has potential as a new
portable device for detecting the running intensity,
and alerting runners to any dangers from excessive
exercise by detecting substantially increased or
decreased blood flow and heart rate.
ACKNOWLEDGEMENTS
We would like to express our special thanks to the
volunteers who participated in the study. We also
would like to thank Mr. Kazuto Mishima of
Vinciamo Incorporated and Mr. Takaaki Miyahara
of NEXIS Incorporated for the integration of the
MEMS blood flow sensor. This work was partially
supported by research grants from the Ministry of
Education, Culture, Sports, Science and Technology
of Japan.
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