Pneumatically Controlled Non-Equibiaxial Cell Stretching Device with Live-cell Imaging

Objective Adherent cell behavior is influenced by a complex interplay of factors, including chemical and mechanical signals. In vitro experiments that mimic the mechanical environment experienced by cells in vivo are crucial for understanding cellular behavior and the progression of disease. In this study, we developed and validated a low-cost pneumatically-controlled cell stretcher with independent control of strain in two directions of a membrane, enabling unequal biaxial stretching and realtime microscopy during actuation. Methods The stretching was achieved by two independent pneumatic channels controlled by electrical signals. We used finite element simulations to compute the membrane’s strain field and particle tracking algorithms based on image processing techniques to validate the strain fields and measure the cell orientation and morphology. Results The device can supply uniaxial, equibiaxial, and unequal biaxial stretching up to 15% strain in each direction at a frequency of 1Hz, with a strain measurement error of less than 1%. Through live cell imaging, we determined that distinct stretching patterns elicited differing responses and alterations in cell orientation and morphology, particularly in terms of cell length and area. Conclusion The device successfully provides a large, uniform, and variable strain field for cell experiments, while also enabling real-time, live cell imaging. Significance This scalable, low-cost platform provides mechanical stimulation to cell cultures by independently controlling strains in two directions. This could contribute to a deeper understanding of cellular response to biorealistic strains and could be useful for future in vitro drug testing platforms. ### Competing Interest Statement The authors have declared no competing interest.