We propose a novel continuous blood pressure monitoring system which is based on an autonomic nervous system, and which considers blood volume simultaneously since both affect blood pressure. An autonomic nervous system regulates blood pressure while blood volume is known to be proportional to the photoplethysmography (PPG) signal. To overcome the limitation of taking blood pressure using a conventional cuff inflating instrument, we designed a system which can achieve continuous blood pressure monitoring. In this research, we used a set of near-infrared light source (940nm) to create a divergent light which was collimated as a uniform beam incident to a wrist surface through a Fourier optics designed transfer lens. We found that the signals became more stable due to the uniform illumination and could be received by a detector. From the signals, we found that the blood volume when converted from blood velocity as measured by an ultrasound probe, showed a strong correlation with the signals. The heart rate variability analyzed from the signals, including time-domain (HR and SDNN) and frequency-domain (LF and HF) indices, could be viewed as physical models since these indices reflect the functions of an autonomic nervous system. Moreover, the research derived regression models can estimate blood pressure. Although it is not common to assess blood pressure from the perspective of an autonomic nervous system and blood flow simultaneously, our research approach seems logical. Our results show the potential for this novel system to be used for blood pressure health monitoring.
Studies have reported that propagating waves can be generated in a finite one-dimensional structure by using two piezoelectric actuators. However it is not easy to generate stable and continuous propagating waves due to the finite boundaries. Driving two piezoelectric actuators at two different locations with sinusoidal signals of 90° phase difference, the propagating waves can be generated on a one-dimensional structure. However, the correlation between the actuators and propagating waves is still not clear. In this paper, we adopt shadow Moiré technique to monitor the full-field out-of-plane deformation response of the generated propagating waves in the one-dimensional (1-D) plate with 180 mm in length. A 200-μm-pitch grating was used in this moiré interferometry setup. The moiré fringe images were captured by a high dynamic camera sequentially. Moiré fringes were analyzed by regions of interested (ROI) capturing technique and Fourier transform to retrieve phase information, which included 1-D plate deformation. After the phase was unwrapped and filtered, the instantaneous surface profile was reconstructed. Our experimental results demonstrated that our system can capture propagating waves generated by using the second (60.025 Hz) and the third (109.500 Hz) resonant modes.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.