Brain Probe FYP

brain modelled with initial tearing

2008-12-20T22:40:00.000-08:00

J Subbaroyan, A finite-element model of the mechanical effects of implantable microelectrodes in the cerebral cortex, Journal of Neural Engineering 2 (2005) 103–113

Brain Young’s Modulus 6000 N/m^2, Poisson’s Ratio 0.45
Probe Young’s Modulus 200 × 10^9 N/m^2, Poisson’s Ratio 0.278

Contact regions: 6 faces of the probe and 4 faces of the tear in the brain.

Fixed support and displacement are same as the previous models.

We shall describe our results based on maximum principal strain, which combines the effect of all the axial strains and hence is representative of the events in the space surrounding the implant.

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2008-12-20T07:33:00.000-08:00

Brain: Young's Modulus 10kPa, Poisson's Ratio: 0.1, Density 1050 kg/m^3
Probe: Young's Modulus 1000GPa, Poisson's Ratio: 0.3

Contact Region: Manual, 6 faces of probe and top surface of brain

Brain: 886 Nodes, 156 Elements
Probe: 423 Nodes, 60 Elements

Boundary Conditions:
Fixed Support: Bottom of Brain
Displacement: -0.01m, y direction of the 8 faces of the probe
Force: 10 N, 8 faces of the probe, in - y direction

Large Deflection: Off

Good papers:
Jeyakumar Subbaroyan, A finite-element model of the mechanical effects of implantable microelectrodes in the cerebral cortex, J. Neural Eng. 2 (2005) 103–113

Devang Gandhi, Functionality Evaluation of Photo-definable Polyimide, Flexible Interface for the Central Nervous System*, IEEE

2008-10-25T06:52:00.000-07:00

2008-10-25T06:51:00.002-07:00

2008-10-25T06:51:00.001-07:00

2008-10-25T06:50:00.000-07:00

Solid Works Brain Probe Model

2008-10-25T06:47:00.000-07:00

But the thing is: I modelled the probe as a hole, instead of as another solid. To be added with Assembly.

Side view

2008-10-25T06:38:00.000-07:00

Front view

2008-10-25T06:36:00.000-07:00

Pin Push In animation :)

2008-10-25T06:32:00.000-07:00

I basically inversed the displacement value. Some limitations, the pin is already inside the block, so no penetration effect. FYI, the pin is bigger than the block hole.

Pin Pull Out Animation

2008-10-24T09:19:00.000-07:00

From Ansys Tutorial. Similar to the project, but need to tweek:

- push in, instead of pull out.

- viscoelastic instead of elastic for the brain

- hydrogel coating

Development thus far

2008-10-24T03:33:00.000-07:00

- Using Solid Works to develop the model, a cylinder with a hole of the shape of the brain probe
- Investigating into Ansys, Tutorial Chapter 8: Contact Tutorial: Inteference Fit and Pin Pull Out Contact Analysis.
- Planning to make the models in Solid Works then importing them to ANSYS.
- Investigating into visco-elastic properties of brain tissue. How to input the data into the material properties.
- Expected outcome of the project: an animation of stress and strain distribution of the brain tissue, as the brain probe is penetrating and as the hydrogels expanding.
- Hypothesis: the stress and strain are not significant, thus the inflamation observed during implant is caused by biological phenomenon.
- Hoping to get training / course in Ansys / Solid Works.
- Investigating into "animation" of Solid Works.

First Entry

2008-10-24T03:30:00.000-07:00

First of all, I would like to thank my friend for the idea.

The purpose of this blog is to update the development of the Final Year Project: The Effect of Probing the Brain with a Neural Probe: an Analysis of the stress and strain distribution in the Brain Using Finite Element Method.

Any comments are welcome. :)

Bobby Tantri