Haptic-STM: A human-in-the-loop interface to a scanning tunneling microscope

Abstract

The operation of a haptic device interfaced with a scanning tunneling microscope (STM) is presented here. The user moves the STM tip in three dimensions by means of a stylus attached to the haptic instrument. The tunneling current measured by the STM is converted to a vertical force, applied to the stylus and felt by the user, with the user being incorporated into the feedback loop that controls the tip-surface distance. A haptic-STM interface of this nature allows the user to feel atomic features on the surface and facilitates the tactile manipulation of the adsorbate/substrate system. The operation of this device is demonstrated via the room temperature STM imaging of C(60) molecules adsorbed on an Au(111) surface in ultra-high vacuum.

Influence of the Central Metal Ion on the Desorption Kinetics of a Porphyrin from the Solution/HOPG Interface

“…STM has the potential to track single molecules on a time scale of milliseconds to hours and allows one to study the dynamics of monolayer formation on surfaces. As advances in STM continue, new doors open for investigating and understanding various surface phenomena under previously inaccessible conditions. − For example, Jahanbekam et al showed that by enclosing the whole STM body in a controlled chamber one can perform temperature dependent studies on volatile solvents such as toluene (up to at least 75 °C) …”

Haptic Sensation-Based Scanning Probe Microscopy: Exploring Perceived Forces for Optimal Intuition-Driven Control

“…The device is operated via device drivers, calibration software, and the Open-Haptics 3.5 application programming interface (API) for the C/C ++ languages. It possesses a positional resolution of 1100 dots per inch (dpi), a workspace of 160 W × 120 H × 120 D mm, and a maximum force output of 7.9 N, nearly double the resolution of haptic devices used in previous experiments 24 ; the high resolution is ideal for obtaining smoother-feeling surfaces and forces.…”

“…A common choice is to use the input signal as the basis for the force curve, and either use the signal itself or a scaled version of it to determine how the surface feels. 24 This method, however, may not be the most ergonomically sound solution. The only technical constraint of the 'feeling function' used is that it must prevent drastic force vs. tip height dependencies which can lead to unstable operation.…”

“…[21][22][23] More recently, ultra-high vacuum (UHV) STM measurements -where surface impurities were eliminated -that included haptic arm control were performed on atomically smooth Au(111) surfaces with adsorbed C 60 molecules. 24 That work demonstrated that when STM feedback is controlled with tunneling current rather than tip-sample forces, the tunneling current could reliably be used to control the haptic arm force, allowing the operator to feel atomic step edges, and to even manipulate C 60 molecules. Though lacking force-feedback, experiments using infrared cameras mapped three-dimensional hand movement to AFM tip movement, and were able to manipulate a PTCDA monolayer on an atomically smooth Ag(111) surface.…”