Biofidelic human brain tissue surrogates

Figures & data

Figure 1. Cross section of a brain showing grey and white matter.

Figure 2. (a) CAD-based mold design for test coupons and (b) 3D printed mold with test coupons.

Figure 3. Brain tissue surrogate samples marked for mechanical testing.

Figure 4. Brain tissue surrogates tested in tension.

Figure 5. Brain tissue simulant tests and comparison with data from the literature [41].

Table 1. Silicone composition ranges for grey and white matter tissues at low and high strain rates.

	Two-part silicone composition
Brain tissue type	Part A (%)	Part B (%)	Strain rate (mm/s)
White matter (low)	30–60	40–70	2.5 (low)
White matter (high)	20–30	70–80	30 (high)
Grey matter (low)	0–20	20–80	2.5 (low)
Grey matter (high)	0–10	10–90	30 (high)

Table 2. Control test specimen compositions for mimicking mean brain tissue biomechanical properties and for repeatibility tests.

Controls tests
Control specimen no.	Silicone composition	Brain tissue simulated	Number of tests
1	50% A, 50% B	White matter (low)	8
2	30% A, 70% B	Grey matter (low)	10
3	10% A, 90% B	White matter (high)	7
		Grey matter (high)

Figure 6. Brain tissue composition (control specimen 1) mimicking mean white matter mechanical behavior [41] at low strain rate testing, tested for repeatibility.

Figure 7. Brain tissue composition (control specimen 2) mimicking mean grey matter mechanical behavior [41] at low strain rate testing, tested for repeatibility.

Figure 8. Brain tissue composition (control specimen 3) simulating mean grey and white matter mechanical properties [41] at high strain rate testing (30 mm/s), tested for repeatibility.

Figure 9. Average polynomial trendline fits of the silicone specimens tested at high and low strain rates (based on Figure 5) for hyperelastic curve fitting.

Table 3. Hyperelastic curve fit parameters for the average stress vs. stretch plots of silicone specimens (brain tissue simulants) corresponding to Figure 9.

Hyperelastic curve fitting results
	Fung		Mooney–Rivlin		Yeoh			Humphrey		Veronda–Westmann
Average specimen composition	μ	b	c1	c2	c1	c2	c3	c1	c2	c1	c2
70% A, 30% B	24.0	−0.05	0.00060	0.0110	0.0099	−0.00110	−0.00095	−22.2	−0.46	−0.038	−0.480
60% A, 40% B	18.5	0.01	0.00020	0.0090	0.0078	−0.00094	−0.00062	−17.3	−0.46	−0.030	−0.475
50% A, 50% B	13.0	−0.20	0.00001	0.0061	0.0054	−0.00090	−0.00060	−9.4	−0.59	−0.020	−0.480
30% A, 70% B	8.5	−0.13	0.00020	0.0038	0.0033	0.00001	−0.00060	−7.1	−0.50	−0.016	−0.375
20% A, 80% B	6.0	−0.10	0.00020	0.0026	0.0022	0.00030	−0.00070	−5.0	−0.51	−0.010	−0.430
10% A, 90% B	3.0	−0.50	0.00015	0.0012	0.0011	0.00020	−0.00040	−3.0	−0.40	−0.005	−0.400

Table 4. Accuracy of hyperelastic curve fitting estimated using an average R² corellation value calculation.

Accuracy of hyperelastic curve fits
Hyperelastic model	R^2 corellation index
Fung	0.953
Mooney–Rivlin	0.966
Yeoh	0.997
Humphrey	0.984
Veronda–Westmann	0.989

X. Jin, F. Zhu, H. Mao, M. Shen, and K.H. Yang, A comprehensive experimental study on material properties of human brain tissue, J. Biomech., vol. 46, pp. 2795–2801, 2013.

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