Measuring collagen fibril diameter with differential interference contrast microscopy

•DIC microscopy is sensitive to collagen fibril diameter and direction change.•DIC edge intensity shift is minimally affected by small changes in fibril direction.•DIC edge intensity shift is linearly correlated to collagen fibril diameter.•DIC microscopy is capable of live measurements of hydrated fibrils’ diameter.•Collagen fibril diameter change due to dehydration is reversible.