The Effects of Balloon Thickness on the Viability of a Microfluidic Cell Compression Device

Abstract

Abstract Cells respond to mechanical stimuli, and microfluidic devices are used to create highly controlled environments for cellular mechanobiology studies. Previously, we developed a microfluidic cell compression device using photolithography and soft lithography. The device consisted of an array of thin polydimethylsiloxane (PDMS) balloons that would inflate under an applied pressure. Hydrogel scaffolds seeded with cells placed over these balloons were shown to be compressed during device operation. The height of the inflated balloons was found to depend on the balloon diameter, and the observed dependency was compared to a theoretical model. The theoretical model predicts that the balloon height is also affected by applied pressure, balloon thickness, and Young’s modulus and Poisson’s ratio of PDMS. In this study, we investigated the effect of the balloon layer thickness on the height to which the balloons can be inflated, following the previous study. Two microfluidic cell compression devices with different balloon thicknesses were fabricated using a 3D printed plastic mold, PDMS, spin-coating, and soft lithography. The height and diameter of the balloons were measured by microscopy imaging and image processing. The device was redesigned to facilitate imaging and following image processing. Fabrication was also slightly altered to improve the control over the balloon thickness. Additionally, Young’s modulus of PDMS was experimentally measured. We found that the balloon height increased with the balloon diameter as expected, but it did not show clear dependence on the balloon thickness, as predicted by the theoretical model. Disagreement with the theoretical model may be due to the assumptions of the model, and errors and uncertainties in fabrication, imaging, and image processing. Height measurements with a secondary method is required for validation of findings.