DESCRIPTION (provided by applicant): This exploratory R21 proposal is to build a novel microelectromechanical system (MEMS) device for direct measurement of the mechanical properties of a collagen fibril. Usually these properties are inferred from larger scale measurements' yielding model dependent results and making it difficult to sort out nanoscale from higher level structure-function relationships. The proposed device is a modification of an existing MEMS device originally designed to test silicon materials at the microscale. We have modified the design of the device for use with smaller specimens having lower moduli. The device fills in a gap between the piconewton level techniques used to measure single molecules and the millinewton devices commercially available for the study of micron to millimeter sized samples. Our group's use of the machine will be primarily to test collagen fibrils relevant to bone. However, we expect the device will have wide applicability in the study of extracellular matrix fibrils in tissues ranging from tendon and ligament to cartilage and bone. Specific Aims 1. Design and fabricate a Microelectromechanical System (MEMS) useful for testing nanofibrils 2. Develop and implement protocols for attaching nanofibrils to MEMS device 3. Test device and protocols using collagen fibrils.