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Biomedical Imaging and Instrumentation

Biomedical Imaging and Instrumentation - Poster Session B

Poster F6 - Developing a Low-Cost Particle Image Velocimetry System

Thursday, October 24, 2024
2:45 PM - 3:45 PM EST
Location: Exhibit Hall E, F & G

Introduction:  Understanding cardiovascular flow structure is necessary in the diagnosis and treatment of anomalies. In vitro experiments provide this useful information without clinical intervention. However, most in vitro methods used to visualize cardiovascular flow are often invasive and disruptive. Particle image velocimetry (PIV) is a non-invasive way to visualize flow, measure velocity, and analyze flow structure. PIV uses a fluid containing particles, a laser to illuminate those particles, and a camera to capture images of the illuminated particles. The images captured with the camera are then analyzed through cross-correlation to calculate the distance and direction traveled by the particles between consecutive images. Velocity can be calculated using the estimated displacement and the known time between the images. Typical PIV systems require a synchronized high-powered laser and a high-speed camera, which make PIV systems expensive and inaccessible to most. Therefore, there is a need for an accessible, low-cost PIV system.

Materials and

Methods:  The test section of the system used an acrylic pipe surrounded by an acrylic box to minimize the refraction of the laser caused by the curved surface of the pipe. Water was chosen as the testing fluid because it has approximately the same index of refraction as acrylic. Particle to water concentrations of 25, 50, and 100 µL of particles to 2000 mL of water were tested. In addition, the surrounding box was filled with water to further reduce the unwanted refraction of the laser. The length of the pipe was chosen to ensure fully developed flow at the region of interest. Air vents were added to the pipe and surrounding box to minimize the air bubbles in the system. The laser was placed at a height that minimized glare and maximized focus. A phone camera was used to record videos at 30, 60, 240, and 960 frames per second (fps) to determine the best settings to capture laser illumination without a synchronizer. Stands were used to stabilize the tubing and test section, and a tripod was used to stabilize the camera. A steady flow pump was used to power the flow. Clamps were used to optimize the flow rate for the chosen camera and laser settings. A flow sensor was used to measure the flow and provided a comparison for the PIV results.

Results, Conclusions, and Discussions: An accurate PIV system was built for less than $200. The system was able to accurately quantify velocity – within 10% of the measured flow rate. Flow structure and velocity profiles were accurate compared to literature results. 50 µL of particles in 2000 mL of water paired with a camera speed of 60 fps provided the clearest images and the most accurate results. Decreased particle concentration did not provide enough particles per frame, and increased particle concentration overwhelmed the image. Increased frames per second captured images without laser illumination. In conclusion, though there are some limitations in frame rate and flow rate, a low-cost PIV system was designed and provided accurate results. In the future, this system can be used for calibration in future PIV testing and can be used to make PIV more accessible for in vitro flow visualization and analysis.

Acknowledgements (Optional):  This work was supported by NSF REU grant EEC2150076.