Figure 1From: Development of method for evaluating cell hardness and correlation between bacterial spore hardness and durabilityPrinciple for measuring cell and spore hardness using the cantilever of the SPM. (A) Position of the cantilever and cell before measurement. (B) Cantilever moves a fixed distance along the z-axis (measurement). a: Start position of cantilever, b: Position of cantilever after being depressed to apply strain to the cell, ϵ: Physical strain applied by the cantilever over a fixed distance (50 nm), σ: cell physical stress (nN) (C) Diagram of physical stress states for various measurement positions. E: Young's modulus (N/m); σ: cell physical stress (nN); ϵ: physical strain applied by the cantilever (nm) Young’s modulus calculated by E = σ/ϵ. c: Stress in the cell can be accurately measured when the measurement position is the highest point along the x- and y-axes, d: Stress from the slide glass is included in measurements taken at or near the edge of the cell, e: Stress is dispersed if measurement position is slightly away from the highest point.Back to article page