Icon Legend

This session is not in your schedule.

This session is in your schedule. Click again to remove it.

Device Technologies and Biomedical Robotics

Device Technologies and Biomedical Robotics - Poster Session E

Poster V20 - In-Situ Bioprinting Tissue Motion and Topology Compensation Mechatronics System

Saturday, October 26, 2024

10:00 AM - 11:00 AM EST

Location: Exhibit Hall E, F & G

Presenting Author(s)

Sarah Vyvyan

Graduate Student Researcher
Wake Forest School of Medicine
Winston-Salem, North Carolina, United States

Co-Author(s)

MS

Mulham Soudan

Graduate Student Researcher
Wake Forest School of Medicine, United States

Primary Investigator(s)

PB

Philip J. Brown

Academic Faculty
Wake Forest University School of Medicine, United States

Introduction: In-situ bioprinting technology enables complex deposition of 3D bioink structures directly onto the site of damaged tissue, promoting integration and healing. There are several technical hurdles to overcome to print in-situ. These include bioink adhesion and sensitivity to tool head height from the substrate, the ability to sense the distance between extruder nozzle and tissue substrate, and the ability to compensate for both high frequency low amplitude and high amplitude low frequency tissue motion, such as breathing. In this work we aim to create a single degree of freedom, real-time, closed-loop extruder height compensation mechatronics system for high frequency and low amplitude tissue motion and topology.

Materials and

Methods: The mechatronics system consists of a confocal chromatic distance sensor (IFC2421, Micro Epsilon Inc) to measure the distance between sensor and substrate, a piezomotor (LL06 Piezomotor, Piezomotor Inc) actuation system to control the distance between the nozzle and the substrate surface, and custom 3D printed fixtures to couple the components together. The system is controlled using a python script running on a windows 10 machine. Based on the distance readings gathered from the distance sensor, the piezo motor will adjust the height of the nozzle to ensure that the nozzle tip remains 1.5mm from the surface of the tissue. The motion and topology are simulated using a rotating platform holding a custom-made ballistic gel disc. These discs have a topology mimicking that of physiological tissue. The motion is simulated using a 6 degree of freedom parallel manipulator that can mimic complex motion of the heart and lungs in the vertical axis. The first set of experiments aimed to determine the piezomotor response to sensor input. These experiments consisted of getting a distance value from the confocal sensor and measuring the time taken for the piezomotor to move according to that reading. The second set of experiments analyzed the system response when the motor and sensor were coupled, therefore the sensor moves when the motor moves. The final set of experiments consisted of running a set of frequency and amplitude sweeps to determine what conditions or types of movement lead to measurements outside of an acceptable error band.

Results, Conclusions, and Discussions: Initial experiments showed that the motor could accurately respond to input from the sensor with a time delay of 30ms and an average RMSE of 2.8 Microns. After that, the ability to respond to topology accurately and the influence of linear velocity were evaluated. It was found that with a linear velocity ranging from 1-20 mm/s over 95% of the measurements were within the acceptable error band defined in previous literature. The constraints and limitations of the system were then explored in the third experiment by evaluating the system response with various waveforms and frequencies. It was found that the system performed optimally at amplitudes between 0-0.5 mm and frequencies between 0-0.5 Hz. Experiment 3 also showed that the system responds optimally to triangular and sinusoidal waveforms. There was a significant amount of oscillation with the square waveforms.

Acknowledgements (Optional):