Numerical simulation of neural probe inserting into brain tissues based on ANSYS/LS-DYNA / 医用生物力学

ABSTRACT

Objective To establish a neural probe-brain tissue numerical model and investigate tissue injuries induced by probe during its insertion into brain tissues. Methods The material of brain tissue was described by a hyper-viscoelastic constitutive equation. Tissue failure and separation were simulated by the element deletion method based on a maximum principle strain failure criteria, and tissue injuries were quantified by the mean effective strain. Then effects of probe wedge angle, inserting speed and probe stiffness on the acute injury were investigated. Results Tissue strain generated by probe with wedge angle of 150° was increased by 37.1% compared with the strain induced with wedge angle of 90°. Along the insertion path, probe with a slow speed of 100 μm/s induced much higher strain value (>57%) compared to that with relatively faster speed of 500 μm/s, which generated the strain value below 25%. The probe stiffness, however, had a negligible effect on tissue injury. The strain within the tissue was only increased by 1%-2% while the stiffness decreased from 165 GPa to 5 kPa. Conclusions The established numerical model can provide references for the design of neural probe and probe inserting parameters, which will be helpful to reduce tissue injuries induced by probe insertion and thus improve the working life of neural probe to meet the long-term clinical application.