Force is a vector! And when we perform atomic force microscopy, we often select which component of force we want to measure by the orientation of the sensor. It's most common to measure the vertical component, but the lateral component can be very important (take a look at some of my recent publications!).
In this paper, we show that both the normal AND lateral modes of a qPlus sensor can be used. The qPlus sensor (invented by Franz Giessibl) is one of the most exciting developments in AFM because it can be easily incorporated in a low-temperature machine and does not require optical alignment.
For more information, check out Kirpal et al., Rev. Sci. Instrum. 92, 043703 (2021).