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My work on SCG monitoring using MEMS sensors.
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AMBULANT SUBJECT SCG MONITORING WITH MEMS
ACCELEROMETERS
Chenxi Yang
Stevens Institute of Technology
Real Time Heart Rate Recording1
*Varady, Peter, et al. "An advanced method in fetal phonocardiography." Computer Methods and programs in Biomedicine 71.3 (2003): 283-296.
Long term heart rate is a valuable diagnostic measurement
Can detect potential disease
Different techniques show varies information from heart(e.g. :ECG(electrodes), PCG(sound) and SCG(Movement))
Seismocardiogram reflects the mechanical event of heart beat
Could be monitored by MEMS accelerometers
Used to be at rest to avoid noise
Non-invasive attachment near sternal
Heart Rate (FHR) Monitor2
*Chen, Jianfeng, et al. “Fetal heart signal monitoring with confidence factor.” IEEE International Conference on Multimedia and Expo, 2006.
Method Sensor Type Portability Disadvantage
Electrocardiography (ECG) Electrode MediumRely on proper position of
multiple electrodes
Phonocardiogram (PCG) Microphone MediumLimited miniaturization,High environment noise
Seismocardiograph (SCG) MEMS Accelerometers High Motion Artifacts
Comparison between common methods
TOP JOB: Cancelling motion artifact3
MEMS accelerometer is the best choice if motion artifact is cancelled Least preparation needed
Low-cost
Low-power
High-resolution low-noise MEMS accelerometers Wireless transmission possible due to small size
and low power consumption
More details for medical analysis
Provide other information(falling status, sleeping quality, acitivity) at the same-time
Adaptive filter DSP system4
1st• Low-pass filter to reduce high-frequency noise
2nd
• Adaptive Normalized LMS filter
• Pick periodic signal that is useful
3rd
• Peak detection to calculate interval and heart rate
• Ensemble average for medical analysis
Low-pass filter
5
• Subject is firstly steady position and then moving
• Raw data from MEMS Accelerometer • Data after low-pass filtering