Effect of the tip size on AFM cantilever based force sensor

Atomic force microscopy (AFM) cantilever is a widely used end effector for precise force sensing and micro-nanomanipulation at small scale. However, in current researches, the effect of the cantilever tip on the force sensing and manipulation accuracy is rarely considered. In this paper, we investigate how the tip size of the end effector affects the measurement accuracy of the cell adhesion force. First, several end effectors with different tip sizes are fabricated from the same AFM cantilever via focused ion beam (FIB) etching. Then, the single cell detachment force is measured at the same experiment condition by these end effectors, respectively. The results indicate that the sensed adhesion force is susceptible to the tip size of the end effector obviously. In addition, the precision of cell manipulation is also regulated by the contact area between the cell and end effector greatly. These findings will benefit our in-depth understanding on the force interaction at small scale and will provide valid reference for the development of high-precision force sensor and manipulation.