BackgroundThere exists a growing need for a cost-effective, reliable, and portable pulsation simulator that can generate a wide variety of pulses depending on age and cardiovascular disease. For constructing compact pulsation simulator, this study proposes to use a pneumatic actuator based on cam-follower mechanism controlled by a DC motor. The simulator is intended to generate pulse waveforms for a range of pulse pressures and heart beats that are realistic to human blood pulsations.MethodsThis study first performed in vivo testing of a healthy young man to collect his pulse waveforms using a robotic tonometry system (RTS). Based on the collected data a representative human radial pulse waveform is obtained by conducting a mathematical analysis. This standard pulse waveform is then used to design the cam profile. Upon fabrication of the cam, the pulsatile simulator, consisting of the pulse pressure generating component, pressure and heart rate adjusting units, and the real-time pulse display, is constructed. Using the RTS, a series of testing was performed on the prototype to collect its pulse waveforms by varying the pressure levels and heart rates. Followed by the testing, the pulse waveforms generated by the prototype are compared with the representative, in vivo, pulse waveform.ResultsThe radial Augmentation Index analysis results show that the percent error between the simulator data and human pulse profiles is sufficiently small, indicating that the first two peak pressures agree well. Moreover, the phase analysis results show that the phase delay errors between the pulse waveforms of the prototype and the representative waveform are adequately small, confirming that the prototype simulator is capable of simulating realistic human pulse waveforms.ConclusionsThis study demonstrated that a very accurate radial pressure waveform can be reproduced using the cam-based simulator. It can be concluded that the same testing and design methods can be used to generate pulse waveforms for other age groups or any target pulse waveforms. Such a simulator can make a contribution to the research efforts, such as development of wearable pressure sensors, standardization of pulse diagnosis in oriental medicine, and training medical professionals for pulse diagnosis techniques.

The pressure during hyperbaric oxygen treatment may increase oxygen toxicity via an augmented oxygen pressure in the gas. Nevertheless, only a few reports have been published on the effect of cells grown under 2 atmospheric absolute (ATA) pressure. To evaluate the effect of pressure on oxygen toxicity and to study effects in addition to oxygen toxicity, we designed an experiment to compare the effects of normobaric mild hyperoxia (NMH, 40% oxygen) and hyperbaric air condition (HA, air with 2 ATA) on human diploid fibroblasts (HDF) in a hyperbaric incubator. HDFs in both the NMH and the HA condition had a similar oxidative stress response and exhibited premature senescence. To investigate differences in gene profiling in cells grown in the NMH and HA conditions, samples from cells exposed to each condition were applied to microarrays. We found no expression difference in genes related to aging and deoxyribonucleic acid damage, but the expression of genes including cell adhesion, stress response, and transcription were significantly increased in fibroblasts that were responsive to pressure. Among 26 statistically reliable genes, the expression of apoptosis related genes such as ADAM22, Bax, BCL2L14, and UBD, as well as tumor suppressor-related genes like Axin2 and ATF, and also mitogen-activated protein kinase-related genes like mitogen-activated protein kinase kinase kinase 1, histamine receptor, and RAB24, were significantly changed in cells responsive to pressureinduced oxidative stress.

Using the field emission effect of a carbon nanotube (CNT), we characterized a new type of technology for detecting low pressure. The fabricated low pressure sensor is of a triode type, consisting of a cathode (carbon nanotubes field emitter arrays), a grid, and a collector. The gauge described here has a triode configuration similar to that of a conventional hot cathode ionization gauge but also has a cold emission source. Due to the excellent field emission characteristics of CNT, it is possible to make a cost effective cold cathode type ionization gauge. For an effective CNT cathode, we used the screen-printing method and also, we controlled the collector and the grid potentials in order to obtain a high ionization current. We found that the ratio of the ionization current to the CNT cathode current changes according to the pressure in the chamber. In short, we elaborate the various metrological characteristics of a home-made pressure sensor that uses CNTs.

This report describes the results of a key comparison of hydraulic high-pressure standards at 16 national metrology institutes (NMIs: NMIJ/AIST, NPLI, CSIR-NML, NIS, KRISS, SCL, SPRING, NMIA, VMI, NML-SIRIM, KIM-LIPI, NSCL, PTB, NIMT, CMS/ITRI and NIM) was carried out during the period October 2002 to July 2004 within the framework of the Asia-Pacific Metrology Programme (APMP) in order to determine their degrees of equivalence at pressures in the range 10 MPa to 100 MPa for gauge mode. The pilot institute was the National Metrology Institute of Japan (NMIJ)/AIST. All participating institutes generally used hydraulic pressure balances as their pressure standards. High-precision pressure transducers were used as transfer standards. The sensing element of the transducer was a precision quartz crystal resonator. To ensure the reliability of the transfer standard, two pressure transducers were used on a transfer standard unit. Three nominally identical transfer packages were circulated independently to reduce the time required for the measurements. During this comparison, the three transfer standards were calibrated simultaneously at the pilot institute 11 times in total. From the calibration results, the behaviours of the transfer standards during the comparison period were well characterized and it was presented that the capabilities of the transfer standards to achieve this key comparison were sufficient. The degrees of equivalence of each national measurement standard were expressed quantitatively by two terms, deviations from the key comparison reference values and pair-wise differences of their deviations. The degrees of equivalence in this comparison were also transferred to the corresponding CCM key comparison, CCM.M.P-K7. The hydraulic pressure standards in the range 10 MPa to 100 MPa for gauge mode of the 16 participating NMIs were found to be equivalent within their claimed uncertainties.Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the Mutual Recognition Arrangement (MRA).

To meet the need for “standard” testing system for wearable blood pressure sensors, this study intends to develop a new radial pulsation simulator that can generate age-dependent reference radial artery pressure waveforms reflecting the physiological characteristics of human cardiovascular system. To closely duplicate a human cardiovascular system, the proposed simulator consists of a left ventricle simulation module, an aorta simulation module, a peripheral resistance simulation module, and a positive/negative pressure control reservoir module. Simulating physiologies of blood pressure, the compliance chamber in the simulator can control arterial stiffness to produce age-dependent pressure waveforms. The augmentation index was used to assess the pressure waveforms generated by the simulator. The test results show that the simulator can generate and control radial pressure waveforms similar to human pulse signals consisting of early systolic pressure, late systolic pressure, and dicrotic notch. Furthermore, the simulator’s left ventricular pressure-volume loop results demonstrate that the simulator exhibits mechanical characteristics of the human cardiovascular system. The proposed device can be effectively used as a “standard” radial artery pressure simulator to calibrate the wearable sensor’s measurement characteristics and to develop more advanced sensors. The simulator is intended to serve as a platform for the development, performance verification, and calibration of wearable blood pressure sensors. It will contribute to the advancement of the wearable blood pressure sensor technology, which enables real-time monitoring of users’ radial artery pressure waveforms and eventually predicting cardiovascular diseases.