Fig. 1. Principle diagram of tumor cell invasion

Fig. 2. OCT system composition

Fig. 3. “Peak-to-Peak” algorithm verification. (a) OCT image of multi-layer glass; (b) OCT signal intensity distribution curve of multi-layer glass

Fig. 4. Diagram of surface curvature measurement

Fig. 5. Test results after sample cultivating for 48 h. (a) OCT test; (b) H-E slice; (c) laser confocal test results

Fig. 6. Test results of samples with different culture time of 12, 24, and 48 h. (a)-(c) OCT tests; (d)-(f) H-E stained slices

Fig. 7. Cell invasion distance for different culture time

Fig. 8. OCT images of cell invasion with different upper chamber serum volume fractions of 0, 2%, 5%, and 10% and different culture time of 12, 24, and 48 h

Fig. 9. Two-dimensional and three-dimensional images of collagen in conventional culture environment and acidic culture environment (pH=6.8) with upper chamber serum volume fraction of 2% and different culture time of 12, 24, and 48 h

Fig. 10. Invasion distance of tumor cells in different pH culture environments for 48 h (*means that cell culture environment is acidic)

Fig. 11. Quantitative characterization of matrix material decomposition deformation in different culture environments. (a) Collagen thickness; (b) collagen volume; (c) collagen surface curvature (*means that cell culture environment is acidic)