A Transfer Function Model Development for Reconstructing Radial Pulse Pressure Waveforms Using Non-Invasively Measured Pulses by a Robotic Tonometry System

Figures

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  Figure 1. Developed three-peak cam-based radial pulsation simulator for generating age-dependent radial pulse waveforms.

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  Figure 2. Robotic tonometry pulse measurement system to measure the precise pulse wave on the radial artery; (a) a picture of the robotic tonometry system, (b) components of a robotic pressure manipulator, (c) built-in piezo-resistive pressure sensor array, (d) demonstration of actual pulse measurement using a cross line laser guide.

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  Figure 3. A flow of the overall process: (a) Pulse pressure waveform measured on skin above the simulator’s wrist using RTS, (b) skin-vessel transfer function modeling based on artificial skin and vessel mechanical testing results, (c) intravascular pulse pressure waveforms reconstructed from the RTS measurement results by the skin-vessel transfer function, (d) the comparison of the differences between the reconstructed waveforms and the pulse pressure in vessel measured by pressure sensor.

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  Figure 4. Experimental setup for compression testing of the artificial wrist model.

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  Figure 5. Experimental results of the artificial wrist’s mechanical properties: (a) Artificial blood vessel filled with 80 mmHg pneumatic pressure, (b) artificial blood vessel filled with 80 mmHg pneumatic pressure and wrapped with the skin layer.

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  Figure 6. An illustration of spring-dashpot based Kelvin–Voigt model for human wrist.

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  Figure 7. Results of the optimization study (a) Change of objective function, ObjE2,η, with respect to E2 and η (left), whose value is minimized when E2=71.32 MPa and η=39.94 MPa s, (b) The comparison between the reconstructed strain and deformation.

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  Figure 8. Experimental setup using age-dependent cams; (a) tonometric measurement results of radial artery pressure waveforms of subjects by age, (b) fabricated age-dependent cams.

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  Figure 9. Reconstruction of age-related intravascular pressure waveforms: (a) Pulse pressure measured on the skin by the RTS, (b) reconstructed intravascular pulse pressure waveforms by the skin-vessel transfer function.

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  Figure 10. Comparison between the normalized reconstructed pulse waveforms and intravascular waveforms: (a) 650 ms heart rate, (b) 750 ms heart rate.

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  Figure 11. Comparison of AI of pulse pressure waveforms: (a) 650 ms heart rate, (b) 750 ms heart rate.