A completely different approach to the optical microscope, one that involved scanning the surface of an object with a probe, led to the development of the scanning probe microscope (SPM). This device boasts high enough resolution to make out individual atoms and molecules, and is, moreover, much more compact than an electron microscope.

However, scanning the surface of an object is much easier said than done. Imagine a stack of several coins placed on a table. If you were blindfolded and then asked to "scan" the surface of the table with your fingertips, you would probably be able to discover where the stack of coins was, and how the coins are stacked up. Someone with sensitive fingertips could probably even tell how many coins are stacked up, and in which way. However, this is only possible if the tips of the person's fingers are small enough to be able to make out the individual coins. SPMs must be able to carry out the same kind of task at the nano level, and so their probes must also be nano-sized to make out individual atoms. It was only in the late 1990s that the technology for making such thin probes was developed.

In 1983, however, Gerd Binnig and Heinrich Rohrer, two researchers at IBM's Zurich laboratory, invented a different type of SPM—the scanning tunneling microscope (STM)—and succeeded in obtaining the world's first-ever images of atoms (silicon). (Binnig and Rohrer won the 1986 Nobel Prize in physics for this achievement, together with Ernst Ruska, for his invention of the electron microscope in 1931.) STMs can achieve sufficient resolution without having to use such fine probes as other kinds of SPM.