Dynamic mechanical properties of murine brain tissue using micro-indentation

In the past 50 years significant advances have been made in determining the macro-scale properties of brain tissue in compression, tension, shear and indentation. There has also been significant work done at the nanoscale using the AFM method to characterise the properties of individual neurons. However, there has been little published work on the micro-scale properties of brain tissue using an appropriate indentation methodology to characterise the regional differences at dynamic strain rates. This paper presents the development and use of a novel micro-indentation device to measure the dynamic mechanical properties of brain tissue. The device is capable of applying up to 30/s strain rates with a maximum indentation area of 2500 μm(2). Indentation tests were carried out to determine the shear modulus of the cerebellum (2.11 ± 1.26 kPa, 3.15 ± 1.66 kPa, 3.71 ± 1.23 kPa) and cortex (4.06 ± 1.69 kPa, 6.14 ± 3.03 kPa, 7.05 ± 3.92 kPa) of murine brain tissue at 5, 15, and 30/s up to 14% strain. Numerical simulations were carried out to verify the experimentally measured force-displacement results.