Main design issues for embedding onto a wireless miniature robot, a scanning tunneling positioning system capable of atomic resolution over a half-meter diameter surface area

摘要

Implementing instruments in the form of wireless miniature robots designed to operate at the atomic scale requires a positioning system capable of atomic resolution over a relatively large surface area. interferometers or similar instruments are not adequate for such an environment because of the high probability that another robot obstructs the path of the laser during position measurement. As such, we have developed an infrared system based on a position sensing detection technique mounted on an x-y stepping stage where the position of an infrared signal transmitted upward from a miniature wireless robot can be detected with a resolution of ±1.58 μm over a 0.5 meter diameter circular surface. Although a fleet of miniature robots distributed over a relatively large area can be supported simultaneously, the system is still far from reaching positioning accuracy down to the level of a single atom. This is why we are embedding the capability to detect surface features down to the size of a single atom using scanning tunneling microscopy (STM) techniques onto the miniature robots. The dynamic range of the scanning piezo-tube is one of many design issues that must be carefully planned. For instance, the scanning system must be capable of detecting each atom in the scan path in order to determine the distance by "counting" the number of atoms. The maximum scan range must reach the discrimination level of the infrared positioning system despite many artifacts such as non-linearity errors and hysteresis. The feasibility and the design of such system are described.