Session: Government Agency Student Posters

Paper Number: 173113

Video-Based Extraction of Operating Deflection Shapes for In-Process Monitoring of 3d Bio-Printed Structures 

The recent emergence of bio-additive manufacturing has paved the way for new frontiers in healthcare, particularly in addressing the increasing demand for human organ transplants. This technology holds the potential to fabricate complex and precise designs of human organs using biocompatible materials and to save human lives. On the other hand, as 3D bio-constructs are often made from relatively soft, lightweight, and translucent materials, ensuring their structural integrity remains a critical challenge. Traditional methods for assessing structural health generally rely on offline or sensor-based approaches, which may limit efficient assessment due to the nature of the bio-ink materials and geometric constraints. Dynamic properties, such as the operational deflection shapes (ODS) and natural frequencies, are intrinsic properties of the structure that depend on the mass distribution, stiffness, and structural integrity of the object. The presence of any anomaly, such as an embedded defect, may affect these physical properties, which in turn can shift the natural frequencies from the pristine condition and alter the local dynamic boundary conditions, resulting in differences in the ODS. Thus, determining the dynamic properties enables a comparative analysis between healthy and defective structures, aiding process optimization, monitoring structural integrity, and saving operational costs and efforts. Therefore, this study proposes a novel, non-contact, and non-destructive approach using video recordings to determine the vibration characteristics of the 3D bio-printed organ structure under in-situ conditions. A phase-based motion estimation approach has been utilized here to determine the dynamic properties of bio-printed constructs while being fabricated from an extrusion-based 3D bioprinter. The effect of ambient excitation from the 3D bioprinter on the bio-construct was recorded using a high-speed camera at the final layer of printing.  Along with analyzing the dimensional artifacts on the surface from the images captured by the camera, this approach allows for the extraction of the object's motion by examining the phase variation in the video-pixel data of each recorded frame. The motion is also influenced by the internal structural and material properties. Furthermore, by selectively magnifying the motion filtered around the frequencies of interest, the ODS were estimated by this approach. The dynamic characteristics of the bioprinter were considered while determining the modal properties of the bio-construct. In addition to the baseline printing condition, a small hollow shape was designed to simulate embedded defect during printing. The resulting vibration responses were obtained and compared with the results from the baseline conditions. Since the ODS changes the intensity values of each pixel in consecutive frames of the magnified videos, the difference in ODS between the healthy and defective samples was computed and expressed in terms of mean squared error, a metric for image quality assessment. The findings from this study show that the vibration characteristics change depending on the structural integrity, effective mass, and stiffness. These findings represent the promising potential of the proposed method to determine the structural integrity of the 3D bio-printed human organs under in-situ conditions while being printed. Furthermore, the proposed method lays the groundwork to correlate the dynamic properties and print quality, offering a comprehensive solution for quality assurance and process optimization in the fabrication of human organs.

Presenting Author: Md Asif Hasan Khan Georgia Southern University

Presenting Author Biography: I am a graduate student at Georgia Southern University at the department of Mechanical Engineering. My research interest are structural health monitoring, fluid mechanics, vibration, additive manufacturing. Currently, I am working on the structural health monitoring of 3D bio-printing from video-based approach.

Authors:

Md Asif Hasan Khan Georgia Southern University
Md Anisur Rahman Georgia Southern University
Jinki Kim Georgia Southern University