Planar Biaxial Testing Device Capable of Ex Vivo Imaging

Andrew Harris, Michael Megally, Armando Ramil, Megan Wu

Principal Investigator: Dr. Daniela Valdez-Jasso, Ph.D.

Project Mentor: Becky Hardie, Ph.D. 

Abstract

Pulmonary Arterial Hypertension (PAH) is a prevalent medical condition that relies on the structure and function of tissue to provide a diagnosis. Specifically, PAH is prominently investigated by examining collagen fiber orientation in the right ventricle. Although there are commercial device apparatuses available that allow for planar biaxial loading of tissue samples, they are incapable of being used in conjunction with a microscope. Typical planar biaxial devices are too large and contain materials that make them incapable of the tissue samples being imaged simultaneously. We have developed a low-cost and easy-to-use planar biaxial device made of PLA and resin capable of being stretched to λ = 10%. While in this state with an applied load, the device can be used in parallel with a multiphoton microscope to use second harmonic generation imaging. This device is designed so that there is an applied load in one direction in each principal axis. Each applied load is capable of being preloaded individually and then loaded simultaneously when applying the planar biaxial load. There is a locking mechanism that is included to prevent any slipping between the rack-n-pinion and the gears so that any angular to linear displacement is constant.

Summary

• There is no commercial device apparatus that is capable of planar biaxial testing that allows for simultaneous imaging from a microscope

• This device is constructed by using 3D-printed materials resin and PLA to ensure that the device is low-cost and easy to reproduce

• We developed a suture attachment technique which removed the requirement of having additional objects on the tissue

• The device is successfully capable of applying a constant load to tissue samples while able to be placed under a multiphoton microscope objective

• In the future, this project can be expanded to improve the accuracy by improving the stretching mechanism and increasing the number of directions the load is applied in each principal axis

Acknowledgements

We would like to thank Dr. Valdez-Jasso (Ph.D.) for providing us with the opportunity and resources to further develop this project. 

We would also like to thank Becky Hardie (Ph.D.) for her exceptional mentorship and assistance in designing the device to achieve our goals and for teaching us how to operate the 3D printing equipment.