Researchers from the National Institute of Standards and Technology (NIST) and the University of North Carolina have demonstrated a new design for an instrument, a “instrumented nanoscale indenter,” that makes sensitive measurements of the mechanical properties of thin films—ranging from auto body coatings to microelectronic devices—and biomaterials. The NIST instrument uses a unique technique for precisely measuring the depth of the indentation in a test surface with no contact of the surface other than the probe tip itself.

Indenters have a long history in materials research. Johan August Brinell devised one of the first versions in 1900. The concept is to drop or ram something hard onto the test material and gauge the material’s hardness by the depth of the dent. This is fine for railway steel, but modern technology has brought more challenging measurements: the stiffness of micromechanical sensors used in auto airbags, the hardness of thin coatings on tool bits, the elasticity of thin biological membranes. These require precision measurements of depth in terms of nanometers and force in terms of micronewtons.

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