Fabrication and Characterization of a Microscale Cellular Loading Device for Cellular Biomechanical Study

Mechanical stimuli interfere with cellular behaviors under many physiological conditions. To understand the role of mechanical stimuli, engineered devices are developed to apply mechanical loads to cells in vitro. Despite of their usefulness, these devices are limited since they often lack the capacity of spatial load control, which is essential for intercellular study. Moreover, application of both compressive and tensile loads using a single loading device is challenging. Here, we fabricate and characterize a microdevice for applying programmable compressive/tensile loads to live cells. The device consists of two PDMS substrates. The top substrate consists of nine circular membranes with patterned microdots array on the top surfaces. Each membrane is connected with a microfluidic channel built in the bottom substrate. Upon actuation, the fluid in the channels deforms the membranes and applies controllable strain to cells cultured on the membranes. In this design, each membrane can be individually controlled to apply desired strain levels. The surface strain of the PDMS membranes is characterized by mapping the displacement of the dot array. The result of strain analysis shows that, the radial strain at the center of a circular membrane upon deformation ranges from about 5% compressive strain to about 20% tensile strain, validating the capacity of the device in applying both tensile and compressive stresses. Cell testing is performed using trabecular meshwork endothelial cells. Cells on different membranes are subjected to 0.5Hz of compressive or tensile stresses. The result shows that compressive and tensile stresses have different effects on the cells, indicating the device a promising solution for cellular biomechanical study.