1. Cardiovascular Simulator

• Collaboration results with Korea Institute of Oriental Medicine and Miami Univ.

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. 

2. Compact pulsatile simulator based on cam-follower mechanism

• Collaboration results with Korea Institute of Oriental Medicine, Miami Univ. and Hanyang Univ.

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. 

This study first performed in vivo testing of a healthy young man to collect his pulse waveforms using a robotic tonometry system developed by KIOM. 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. 

• In the video, the compact pulsatile simulator was evaluated in conjunction with the Robotic Tonometry System developed by KIOM.

3. Arbitrary Pulse Simulator based on Wave Decomposition Modeling

• Collaboration results with Korea Institute of Oriental Medicine, Miami Univ. and Hanyang Univ.

This study utilizes the wave decomposition modeling approach, which entails separating a single pulse pressure waveform (PPW) into three waveform components, consisting of one forward wave and two backward or reflective waves. based on the physiology of pulse waveforms. It employs a six-degree-of-freedom mathematical model that integrates the three, and the control parameters of these components can be adjusted to generate the desired pulse waveforms This model is then realized in a physical pulse simulation system using three cylindrical cams with continuously varying surface profiles, each representing forward and backward wave components. By controlling the position, the phase, as well as spin speed and direction of the cams, the simulator can reconstruct desired radial pulse waveforms.