Atomic Force Microscope Model

myminifactory

A basic model demonstrates how an atomic force microscope or scanning-tunneling microscope functions to visualize atoms and molecules. Move the scaffold piece along the frame, and the tip will ascend and descend to probe the surface. You can modify the surface with various features such as steps or islands. This simplified explanation conveys the fundamental concept of mapping out a surface that is too small to be seen with visible light. Eventually, I plan to cover the surface so my students can map out what the surface looks like by measuring the change in height of the tip as they "scan" the surface, along with creating other surface structures that can be mapped out. The frame and tip files are set up so the pieces print upside down. This allows the parts to be printed without supports or rafts. Depending on your print bed, a small amount of glue from a glue stick applied to the bed before printing will prevent the longer pieces from curling upwards as they cool. This model continues the discussion that arises when discussing the history of the atom. Once students understand how we discovered the structure of the atom, it is essential to discuss current technologies that teach us about atoms. The atomic force microscope (AFM) is one such technology. Objectives: Students will be able to describe how atomic force/scanning-tunneling microscopy is used to create an image of an atomic surface. Students will be able to translate change in height data from the tip into a drawing of the surface profile. Students will be able to predict changes in height based on added features to the surface such as islands, steps, and holes. Discuss why light microscopes cannot be used to see atoms and molecules. Describe how to slide the scaffold over the surface so the tip rises and falls. Cover the surface so the students cannot see it and let them figure out and discuss how this technique can be used to recreate what an atomic surface looks like, thereby modeling how we can "see" an atomic surface with an AFM. Have students graph the height of the tip vs position in the x and y direction and discuss how the graph shows a profile of the surface. By drawing multiple graphs as the students move the tip across the surface, they can reconstruct a 3D image from 2D slices. This is how AFM and STM functions. AFM Model Graph Paper Folder or cardboard to block view of the models surface