A High Rate Tension Device for Characterizing Brain Tissue

TL;DR

This paper introduces a custom high rate tension device capable of measuring brain tissue mechanics at strain rates up to 90/s, filling a gap between conventional tensile machines and Kolsky bar apparatus for TBI modeling.

Contribution

A novel high rate tension device is developed and calibrated to measure brain tissue properties at strain rates relevant to traumatic brain injury.

Findings

Device achieves strain rates up to 90/s

Can extend strain measurement to 100%

Applicable to other soft tissues like skin

Abstract

The mechanical characterization of brain tissue at high loading velocities is vital for understanding and modeling Traumatic Brain Injury (TBI). The most severe form of TBI is diffuse axonal injury (DAI) which involves damage to individual nerve cells (neurons). DAI in animals and humans occurs at strains > 10% and strain rates > 10/s. The mechanical properties of brain tissues at these strains and strain rates are of particular significance, as they can be used in finite element human head models to accurately predict brain injuries under different impact conditions. Existing conventional tensile testing machines can only achieve maximum loading velocities of 500 mm/min, whereas the Kolsky bar apparatus is more suitable for strain rates > 100/s. In this study, a custom-designed high rate tension device is developed and calibrated to estimate the mechanical properties of brain tissue in tension at strain rates < 90/s, while maintaining a uniform velocity. The range of strain can also be extended to 100% depending on the thickness of a sample. The same apparatus can be used to characterize the dynamic behavior of skin and other soft biological tissues by using appropriately sized load cells with a capacity of 10 N and above.