At the University of Auckland, Michelle Dickinson (above) runs the Nano-Mechanical Research laboratory where diamonds are being used to indent samples at the nano-scale, to test the mechanical properties of a whole range of materials from biological cells to miniatuarised devices.
Since the 1800s, the relative hardness of materials has been measured using a simple scratch test. With advances in technology, these indentation tests can be done on very tiny objects. The diamond tips used in indentation tests are different shapes and sizes depending on the samples being tested and how much pressure is applied. For example, the strength of bone can be tested to see how healthy it is and determine the effects of osteoporosis, and mineralised sea creatures such as sea urchins can be tested to see how they are impacted by ocean acidification. The diamond tips that are used can also be specially designed so they can test biological materials in fluid, for example, brain cells.
Ruth Beran visits the Nano-Mechanical Research laboratory to see some nanoindentation.