Nano-tribological study on the smoothness of writing with a ball-point pen using friction force microscopy

The relationship between human sensation experienced in the use of a material and its physical properties was investigated for the case of writing with a ball-point pen containing water-based ink. Friction force microscopy (FFM) and a writing tester were used to measure friction in nano- and macro-scale, respectively, and their results were correlated with the smoothness of the act of writing. FFM allowed the determination of the optimum concentration of a specific lubricant to be incorporated in the ink to minimize the wear of the bearing material, although no significant relationship was observed with the writing tester. The nano-tribological measurements by FFM provide a significant means to understand the relationship between materials and the smoothness of the act of writing.