Pressure-based Detection of Heart and Respiratory Rates from Human Body Surface using a Biodegradable Piezoelectric Sensor.

This study investigates the relationship between respiration and autonomic nervous system (ANS) activity and proposes a parallel detection method that can simultaneously extract the heart rate (HR) and respiration rate (RR) from different pulse waves measured using a novel biodegradable piezoelectric sensor. The synchronous changes in heart rate variability and respiration reveal the interaction between respiration and the cardiovascular system and their interconnection with ANS activity. Following this principle, respiration was extracted from the HR calculated beat-by-beat from pulse waves.

High-Performance SAW Resonator With Simplified LiTaO/SiO Double Layer Structure on Si Substrate.

In response to the increased mobile data traffic, there is a growing need for more low-loss RF band filters with steep frequency characteristics, and high-quality ( Q )-factor and low-temperature coefficient of frequency (TCF) resonators are required to achieve this. We previously reported that for a surface acoustic wave (SAW) resonator on a three-layer structure, which is composed of a thin LiTaO (LT) plate whose orientation is 50° rotated YX propagation, SiO layer, and AlN layer on a Si substrate, a Q-factor several times higher than that of an SAW resonator on a standard 42° rotated YX propagation LiTaO (42YX-LT) substrate could be obtained. In this study, we investigated this layer structure and found that a two-layer structure, in which the AlN layer is removed, achieves a high Q -factor.

High-Performance SAW Resonator on New Multilayered Substrate Using LiTaO Crystal.

To develop the high-performance filters and duplexers required for recent long-term evolution frequency bands in mobile handsets, a surface acoustic wave (SAW) resonator is needed that has a higher quality (Q) and a lower temperature coefficient of frequency (TCF). To achieve this, the authors focused on acoustic energy confinement in the depth direction for a rotated Y-X LiTaO (LT) substrate. Characteristics of multilayered substrates with low-impedance and high-impedance layers under LT layer were studied numerically in terms of acoustic energy distribution, phase velocity, coupling coefficient, and temperature characteristics employing a finite-element method simulation.