Alice White

Scaffolds for Heart Tissue Engineering and their Mechanical Responses

ABSTRACT
This project focuses on designing scaffolds that can be used for heart tissue engineering and simulating their mechanical responses when exposed to the force of an average cardiomyocyte. The designed scaffolds have a honeycomb accordion architecture and were made in both isotropic and anisotropic configurations. The full array of structures measured less than 800um in length and width, and 50um in height. The program Describe (Nanoscribe GmbH, Germany) was used to format the files of the structures, which were then printed with a commercial 2PP system (Nanoscribe Photonic Professional GT, Germany). Structures were also simulated using COMSOL Multiphysics to show the mechanical responses when 5uN of force were acting on the walls, both outward and inward.

CONCLUSION
The Nanoscribe GmbH can be used to print accordion honeycomb structures of less than a millimeter at a useful resolution. With adequate power and scanning speed these structures can be printed and are robust enough to be coated in fibronectin where cardiomyocytes can be cultured. If printed in PETA, or other materials with similar mechanical properties to PMMA, the structures allow for cardiomyocytes (with a force of 5 uN) to stretch as needed. Next steps include confirmation of the material properties.

UNDERGRADUATE STUDENT
Nicole Bacca

GRADUATE STUDENTS
Victoria Wiedorn and Mustafa Cagatay Karakan

Cardiomyocyte Actuation with the use of Microfluidic Devices

ABSTRACT
Actuation devices at the nano and micro scales are in necessity to develop cultured human cardiomyocytes differentiated from induced pluripotent stem cells (iPSCs), because in their early-stages they lack characteristics and properties from adult cardiomyocytes. Therefore, actuator technologies are in demand to stimulate and help emulate the physiology of the adult cardiomyocytes. Through the research of metamaterials, dynamic scaffolds can be designed with incorporated fluid driven actuators using microfluidic devices to provide the necessary stimulation during different phases of the tissue maturity. With the use of Computer Aided Design (CAD) and finite element Multiphysics simulation software, a behavior of the designed actuator can be observed before going into the fabrication and testing phases of the project.

CONCLUSION
After designing multiple structures and developing numerous simulation models to precisely emulate the behavior of the pressure driven actuator, a operational model was successfully designed. This FSI model can be applied to other structures with similar fluid-surface interactions and can be further studied to understand the needed parameters to cause deformation of other microscale actuators. The simulation results shown are based on a parametric sweep, which is a feature that allows to obtain multiple results with different values of a same variable within a single study. The structure was also successfully fabricated on multiple surfaces using different photoresistors. The actuators were observed under a microscope and showed good definition of the features. Overall, these guidelines can be applied to create other actuators and find new application for them.

UNDERGRADUATE STUDENT
Jean Paul Soto Aquino

GRADUATE STUDENTS
Victoria Wiedorn and Mustafa Cagatay Karakan