A miniature mechanical testing device for testing hydrogel-based biomaterials in a confocal microscope

Cardiac muscle cells are the fundamental building blocks of the heart, yet little is known about their mechanical properties in either healthy or diseased states. While many have explored unloaded myocyte behavior under a variety of interventions, methods for force measurements are limited due to cell fragility. Here, we present a custom device for manipulation and mechanical testing of hydrogels embedded with delicate cardiac muscle cells. Consisting of a custom disposable flexure, which is easily interchangeable, the device has the potential for high throughput testing of cell-gel constructs. Additionally, the mechanical testing device is the size of a microscope slide - appropriate for use in most microscopes, for simultaneous imaging of the sample. The mechanical properties of a gelatin-methacryloyl hydrogel sample were assessed, and 3D volumes of gel imaged using a confocal microscope. The Young's modulus of the gel was found to be 33kPa.Clinical Relevance- High-throughput testing provides the potential to gain insight into cardiac cell mechanics. Experimentation under the influence of a variety of pharmacological interventions could improve the rate at which treatments for cardiac disease are developed. Furthermore, methods may be extended to other embedded biological tissues.