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Pulse diagnosis is important in oriental medicine. The purpose of this study is explaining the mechanisms of pulse with a cardiovascular simulator. The simulator is comprised of the pulse generating part, the vessel part, and the measurement part. The pulse generating part was composed of motor, slider-crank mechanism, and piston pump. The vessel p...
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Citations
... ViVitro Labs, Inc., developed an endovascular simulator that can generate pulsatile flow and blood pressure waveforms similar to humans [21]. Lee et al. developed a cardiovascular simulator for studying the depth, rate, shape, and strength of radial pulses [22]. Tellyes Scientific Inc. developed a pulse-training simulator (Victor Pulse) that can adjust the characteristic parameters of the pulse wave by manipulating the opening time of the hydraulic valve and the hydraulic pressure intensity [23]. ...
With the emergence of the metaverse and other human–computer interaction technologies, promising applications such as medical palpation training are growing for training and education purposes. Thus, the overarching goal of this study is to develop a portable and simple pulse pressure simulator that can reproduce age-specific pulse pressure waveforms for medical palpation training. For training applications, the simulator is required to produce accurate radial pulse waveforms consistently and repeatedly. To this end, exploiting the cam-based pneumatic pulse generation mechanism, this study intends to develop a cylindrical (or 3D) cam whose continually varying surface contains a wide range of age-related pulse pressure profiles. To evaluate the performance of the simulator, the reproduced pulse waveforms were compared with approximate radial pulse pressure waveforms based on in vivo data in terms of the augmentation index (AI) and L2 error. The results show that the errors were less than 10% for all ages, indicating that the proposed pulse simulator can reproduce the age-specific pulse waveforms equivalent to human radial pulse waveforms. The findings in this study suggest that the pulse simulator would be an excellent system for RAPP palpation training as it can reproduce a desired pulse accurately and consistently.
... N) forces. Based on pulse depth, rate, shape, and strength, physicians can perceive the patient's health conditions [1][2][3]. Pulse depth describes the vertical position of a pulse. Pulse rate describes the number of pulses per unit time. ...
... For instance, the ViVitro Endovascular Simulator from ViVitro Labs uses pumps to deliver pulsatile flow. Lee et al. [1] developed a cardiovascular simulator using a stepping motor, slider-crank mechanism, piston pump, water, and glycerin to generate pulsatile flow for simulating typical TCM pulse waveforms. Koo et al. [22] built a radial pulsation simulator using a peristaltic pump and magnetorheological (MR) fluids. ...
... In addition, an effective recorder's measured profile should fit the original waveform profile as much as possible. Therefore, in this study, a score was given using the following equation to evaluate a design: Score = R-squared value + norm peak volt (1) where "R-squared value" is the fit between the original cam profile and the measured profile and "norm peak volt" is the normalized peak voltage of the output signals of each design. Based on the results of the 9 experiments, a standard analysis of the Taguchi method was conducted. ...
Pulse palpation is an effective method for diagnosing arterial diseases. However, most pulse measurement devices use preconfigured pressures to collect pulse signals, and most pulse tactile simulators can only display standard or predefined pulse waveforms. Here, a portable interactive human pulse measurement and reproduction system was developed that allows users to take arbitrary pulses and experience realistic simulated pulse tactile feedback in real time by using their natural pulse-taking behaviors. The system includes a pulse tactile recorder and a pulse tactile player. Pulse palpation forces and vibrations can be recorded and realistically replayed for later tactile exploration and examination. To retain subtle but vital pulse information, empirical mode decomposition was used to decompose pulse waveforms into several intrinsic mode functions. Artificial neural networks were then trained based on intrinsic mode functions to determine the relationship between the driving signals of the pulse tactile player and the resulting vibration waveforms. Experimental results indicate that the average normalized root mean square error and the average R-squared values between the reproduced and original pulses were 0.0654 and 0.958 respectively, which indicate that the system can reproduce high-fidelity pulse tactile vibrations.
... Each peak involved two extrema which correspond to different levels of pressure in the pulse waveform. The wave patterns resemble slippery pulse type [214] in the waveform which can be used to extract and communicate the pulse information. ...
This dissertation focuses on the development of architected structures via direct additive manufacturing (AM) and novel template-assisted techniques for sensing and tissue engineering applications. Although AM technologies have eased the fabrication of architected structures, limitations arise while printing high-flex 3D complex shapes. To date, no feasible fabrication method has been introduced for high-flex electronics with architected complex geometries in a three-dimensional system. In the current thesis, employing a high-speed material jetting system for direct 3D printing of high-viscose silicone-based inks with carbon fiber additives is introduced. The 3D printed sandwich-like sensors with a silicone-carbon fiber layer (as the sensitive counterpart) and two silicone layers (as the protective and packaging layers) showed enhanced durability for biomonitoring applications. The carbon fiber content was optimized and set to 30 wt.% for printability, UV curability, and electrical conductivity so that high piezoresistive sensitivity (gauge factor in order of ∼400) was obtained. However, due to the limitations of direct 3D printing, a novel template-assisted fabrication process is introduced for the development of elastomeric structures with complex-shape designs. The silicone prepolymer was engineered with additives allowing on-demand structural shrinkage upon solvent treatment, and consequently, fabrication of micrometer-size features was feasible. This enabled 3D printing at a larger scale compatible with extrusion 3D printer resolution followed by isotropic shrinkage. This procedure led to a volumetric shrinkage of up to ~70% in a highly controllable manner. In this way, pore sizes in the order of 500–600 μm were obtained. The proposed low-cost fabrication method not only enabled the high-resolution fabrication of complex-shaped elastomeric structures but was adopted and modified for the fabrication of 3D flexible electronics. In this dissertation, a fabrication scheme based on accessible methods is introduced to surface-dope porous silicone sensors with graphene. The sensors are internally shaped using fused deposition modeling (FDM) 3D printed sacrificial molds. The presented procedure exhibited a stable coating on the porous silicone samples with long term electrical resistance durability over ∼12 months period and high resistance against harsh conditions (exposure to organic solvents). Besides, the sensors retained conductivity upon severe compressive deformations (over 75% compressive strain) with high strain-recoverability and behaved robustly in response to cyclic deformations (over 400 cycles), temperature, and humidity. The sensors exhibited a gauge factor as high as 10 within the compressive strain range of 2−10% and showed strong capability in sensing movements as rigorous as walking and running to the small deformations resulted by human pulse. This dissertation also introduces a robust and scalable approach for forming 3D multilayered complexly architected perfusable networks within highly cellularized hydrogel constructs. Perfusable interconnected networks could assist in sustaining thick cellularized tissue constructs through uniform perfusion of body fluids. The hydrogel constructs were patterned through two-step sacrificial molding. The cell-laden hydrogel scaffolds showed high cell viability of over 90% and robust mechanical behavior. Besides, conflicting design criteria in tissue engineering scaffolds necessitate investigating the structure-properties of the tissue engineering scaffolds and implants. This research shows that defining high local macroporosity at the implant/tissue interface improves the biological response. Gradually decreasing macroporosity from the surface to the center of the porous constructs provides mechanical strength. Furthermore, mechanical studies on the unit cell topology effects suggest that the bending dominated architectures can provide significantly enhanced strength and deformability, compared to stretching-dominated architectures in the case of complex loading scenarios.
... In TCM, pulses are classified into 28 single pulse types based on four main elements, pulse depth, pulse rate, pulse shape, and pulse strength [1,14]. Pulse depth describes the vertical position of a pulse. ...
Accurate pulse diagnosis is often based on extensive clinical experience. Recently, modern computer-aided pulse diagnostic methods have been developed to help doctors to quickly determine patients' physiological conditions. Most pulse diagnostic methods used low-dimensional feature vectors to classify pulse types. Therefore, some important but subtle pulse information might be ignored. In this study, a novel high-dimensional pulse classification method was developed to improve pulse diagnosis accuracy. To understand the underlying physical meaning or implications hidden in pulse discrimination, 71 pulse features were extracted from the time, spatial, and frequency domains to cover as much pulse information as possible. Then, Principal Component Analysis (PCA) was applied to extract the most representative components. Artificial neural networks were trained to classify 10 different pulse types. The results showed that PCA accounted for 95% of the total variances achieved the highest accuracy of 98.2% in pulse classification. The results also showed that pulse energy, local instantaneous characteristics, main frequency, and waveform complexity were the major factors determining pulse discriminability. This study demonstrated that using high-dimensional features could retain more pulse information and thus, effectively improve pulse diagnostic accuracy.
... Each peak involved two extrema which correspond to different levels of pressure in the pulse waveform. The wave patterns resemble slippery pulse type 68 in the waveform which can be used to extract and communicate the pulse information. ...
Three-dimensional flexible porous conductors have significantly advanced wearable sensors and stretchable devices because of their specific high surface area. Dip coating of porous polymers with graphene is a facile, low cost, and scalable approach to integrate conductive layers with the flexible polymer substrate platforms; however, the products often suffer from nanoparticle delamination and overtime decay. Here, a fabrication scheme based on accessible methods and safe materials is introduced to surface-dope porous silicone sensors with graphene nanoplatelets. The sensors are internally shaped with ordered, interconnected, and tortuous internal geometries (i.e., triply periodic minimal surfaces) using fused deposition modeling (FDM) 3D-printed sacrificial molds. The molds were dip coated to transfer-embed graphene onto the silicone rubber (SR) surface. The presented procedure exhibited a stable coating on the porous silicone samples with long-term electrical resistance durability over ∼12 months period and high resistance against harsh conditions (exposure to organic solvents). Besides, the sensors retained conductivity upon severe compressive deformations (over 75% compressive strain) with high strain-recoverability and behaved robustly in response to cyclic deformations (over 400 cycles), temperature, and humidity. The sensors exhibited a gauge factor as high as 10 within the compressive strain range of 2–10%. Given the tunable sensitivity, the engineered biocompatible and flexible devices captured movements as rigorous as walking and running to the small deformations resulted by human pulse.
... This simulator is characterized as a super pump that generates a pulsating flow, and the generated pulsatile flow passes through a viscoelastic impedance adapter, a pump head, and a compliance chamber to an aortic anatomical model. Lee et al. developed a cardiovascular simulator for studying the depth, the rate, the shape, and the strength of radial pulses [16]. The simulator is comprised of a pulse generating part, a vessel part, and a measurement part. ...
Background
There 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.
Methods
This 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.
Results
The 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.
Conclusions
This 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.
... To modernize pulse diagnosis, the mechanisms of pulse diagnosis need to be explained in terms of modern science. Previous studies in this area [1][2][3] can be classified into three categories: clinical studies, mathematical simulation studies, and physical simulator studies. Conducting clinical research is expensive and time-consuming, and manipulating biological variables is very challenging [4]. ...
This research was undertaken to develop a cardiovascular simulator for use in the study of pulse diagnosis. The physical (i.e., pulse wave transmission and reflection) and physiological (i.e., systolic and diastolic pressure, pulse pressure, and mean pressure) characteristics of the radial pulse wave were reproduced by our simulator. The simulator consisted of an arterial component and a pulse-generating component. Computer simulation was used to simplify the arterial component while maintaining the elastic modulus and artery size. To improve the reflected wave characteristics, a palmar arch was incorporated within the simulator. The simulated radial pulse showed good agreement with clinical data.
Arterial simulators are a useful tool to simulate the cardiovascular system in many different fields of application and to carry out in vitro tests that would constitute a danger when performed in in vivo conditions. In the literature, a thriving series of in vitro experimental set-up examples can be found. Nevertheless, in the current scientific panorama on this topic, it seems that organic research from a metrological and functional perspective is still lacking. In this regard, the present review study aims to make a contribution by analyzing and classifying the main concerns for the cardiovascular simulators proposed in the literature from a metrological and functional point of view, according to their field of application, as well as for the transducers in the arterial experimental set-ups, measuring the main hemodynamic quantities in order to study their trends in specific testing conditions and to estimate some parameters or indicators of interest for the scientific community.
Background
In pulse signal analysis and identification, time domain and time frequency domain analysis methods can obtain interpretable structured data and build classification models using traditional machine learning methods. Unstructured data, such as pulse signals, contain rich information about the state of the cardiovascular system, and local features of unstructured data can be extracted and classified using deep learning.
Objective
The objective of this paper was to comprehensively use machine learning and deep learning classification methods to fully exploit the information about pulse signals.
Methods
Structured data were obtained by using time domain and time frequency domain analysis methods. A classification model was built using a support vector machine (SVM), a deep convolutional neural network (DCNN) kernel was used to extract local features of the unstructured data, and the stacking method was used to fuse the above classification results for decision making.
Results
The highest average accuracy of 0.7914 was obtained using only a single classifier, while the average accuracy obtained using the ensemble learning approach was 0.8330.
Conclusions
Ensemble learning can effectively use information from structured and unstructured data to improve classification accuracy through decision-level fusion. This study provides a new idea and method for pulse signal classification, which is of practical value for pulse diagnosis objectification.
