A Micromachined Device for Mechanical Testing of Nano-scale Materials and Structures

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We propose to fabricate a micromachined structure for tensile testing of freestanding nano-scale thin films. The design will combine elements that currently exist in different mechanical testing devices and will offer several new features as well. The benefits of the proposed device include integrated load measurement with a piezoresistive force sensor, very sensitive stress measurement at high strain rates, table-top testing compatibility, in-situ electron microscope testing compatibility, intrinsic specimen alignment, and protection of the specimen during handling. The combined capabilities will allow exploration of time and temperature dependent performance of various thin film materials. The process flow for device fabrication will be compatible with a wide variety of test materials and will be suitable for exchange between laboratories. The finished device will be demonstrated through a study of strain rate effects in aluminum and aluminum alloy films of 20-100 nm dimensions. A fatigue fracture study performed on aluminum films will also showcase the unique capabilities of the test device. The proposed program will provide critical information necessary for reliable design of devices that depend on nano-scale structural components. Although graduate students will be performing the majority of the work, several undergraduate students will be engaged each year in hands-on research, exposing them to concepts and techniques being developed for the emerging field of nanomaterials. Significant representation of women will be a part of this effort, as has been demonstrated in prior projects. Furthermore, freshmen will benefit from hands-on projects based on advanced materials through a new course in development intended for all Lehigh engineering students. Infrastructure enhancements to the Lehigh University Nano- and Micro-Mechanical Behavior Laboratory and the Electron Microscopy Facility will fuel future collaborations in mechanical behavior of nano-scale materials and structures