Table 1.
Results from the microsphere indentation experiments
| Gel thickness h (μm) | Indentation depth δ (μm) | Dimensionless parameters |
Hertz modulus EH (Pa) | Corrected modulus E (Pa) | Linear modulus EL (Pa) | |||
|---|---|---|---|---|---|---|---|---|
| R/h | δ/h | ω | ||||||
| Sample 1 | 51.75 ± 5.42 | 19.65 ± 1.17 | 6.14 | 0.38 | 3.556 | 3226 ± 288.1 | 312 ± 85.6 | 359 ± 92.5 |
| Sample 2 | 153.27 ± 15.37 | 41.05 ± 1.59 | 2.07 | 0.27 | 0.413 | 1068 ± 62.1 | 344 ± 49.6 | 368 ± 51.7 |
| Sample 3 | 272.26 ± 17.54 | 64.41 ± 1.74 | 1.17 | 0.24 | 0.145 | 544 ± 22.0 | 261 ± 20.4 | 263 ± 19.2 |
| Sample 4 | 520.94 ± 6.29 | 89.74 ± 1.37 | 0.61 | 0.17 | 0.034 | 330 ± 7.6 | 230 ± 6.1 | 216 ± 5.9 |
| Sample 5 | 771.37 ± 30.05 | 112.66 ± 2.49 | 0.41 | 0.15 | 0.0147 | 235 ± 7.8 | 188 ± 6.9 | 172 ± 6.8 |
| Sample 6 | 1053.5 ± 23.92 | 133.40 ± 2.54 | 0.30 | 0.13 | 0.0075 | 182 ± 5.2 | 158 ± 4.6 | 143 ± 4.5 |
| Sample 7 | 133.75 ± 2.26 | 31.36 ± 1.37 | 4.37 | 0.23 | 1.039 | 1633 ± 107.0 | 334 ± 33.7 | 374 ± 38.1 |
Gel thickness h and indentation depth δ were measured in experiments using the microscopic indentation method. Samples 1–6 were indented by a steel ball of radius R = 317.5 μm (six measurements per sample). Sample 7 was indented by a glass sphere of radius R = 585 μm (10 measurements). Average values of dimensionless parameters R/h, δ/h, and ω are listed in the table. The Hertz modulus EH was calculated using Hertz theory (Eq. 1) with ν = 1/2. The corrected modulus E was determined using the correction factor (Eq. 6) and the frictionless interface condition. The linear modulus EL was calculated using the correction factor provided in Dimitriadis et al. (21) (see their Eq. 12). All of the data except for the dimensionless parameters are presented as the mean ± SD.