Estimation of Blood Pressure in the Radial Artery Using Strain-Based Pulse Wave and Photoplethysmography Sensors.

Blood pressure (BP) is a crucial indicator of cardiac health and vascular status. This study explores the relationship between radial artery BP and wrist skin strain. A BP estimation method based on the physical model of wrist skin tissues and pulse wave velocity (PWV) is proposed. A photoplethysmography (PPG) sensor and strain gauge are used in this method. The developed strain-based pulse wave sensor consists of a pressing force sensor, which ensures consistent pressing force, and a strain gauge, which measures the cardiac pulsation on the wrist skin. These features enable long-term BP monitoring without incurring the limb compression caused by a cuff. Thus, this method is useful for individuals requiring continuous BP monitoring. In this study, the BP of each participant was measured in three modes (before, during, and after exercise), and the data were compared using a clinically validated sphygmomanometer. The percentage errors of diastolic and systolic BP readings were, respectively, 4.74% and 4.49% before exercise, 6.38% and 6.10% during exercise, and 5.98% and 4.81% after a rest. The errors were compared with a clinically validated sphygmomanometer.

An integrated thermal compensation system for MEMS inertial sensors.

An active thermal compensation system for a low temperature-bias-drift (TBD) MEMS-based gyroscope is proposed in this study. First, a micro-gyroscope is fabricated by a high-aspect-ratio silicon-on-glass (SOG) process and vacuum packaged by glass frit bonding. Moreover, a drive/readout ASIC, implemented by the 0.25 µm 1P5M standard CMOS process, is designed and integrated with the gyroscope by directly wire bonding. Then, since the temperature effect is one of the critical issues in the high performance gyroscope applications, the temperature-dependent characteristics of the micro-gyroscope are discussed. Furthermore, to compensate the TBD of the micro-gyroscope, a thermal compensation system is proposed and integrated in the aforementioned ASIC to actively tune the parameters in the digital trimming mechanism, which is designed in the readout ASIC. Finally, some experimental results demonstrate that the TBD of the micro-gyroscope can be compensated effectively by the proposed compensation system.

SU-8 based continuous-flow RT-PCR bio-chips under high-precision temperature control.

Being beneficial from dramatic progress in bio-chemical and micro-electro-mechanical technologies, DNA manipulation devices can be miniaturized to expedite amplification processing for virus detection. Polymerase chain reaction (PCR) and reverse transcription polymerase chain reaction (RT-PCR) are two typical examples of them. In this report, a micro-RT-PCR (microRT-PCR) chip is designed to quantitatively detect tumor viruses. Test sample reservoirs, RT-PCR meanders, and capillary electrophoresis are integrated on a SU-8 based monolithic chip. A high-precision temperature control module is well developed by embedding signal amplification circuits and an Intel 8051 microprocessor. The integrated system exhibits high efficacy for heat transfer, exemption of fluid flow clogging and superior sensitivity to precisely control the required reaction temperatures in all heated zones of microRT-PCR unit. Intensive simulations and experiments are presented to verify the validity of the fabricated bio-chip.