Abstract:

The science of haptics has received a great attention during the last decade. The major application trends of haptic technology include simulation, training, and education. In particular, the adoption of haptic technologies in education can greatly help to make the students feel sensations not directly experienceable and typically only reported as notions in textbooks.
In this work, we present a haptically-enhanced system for the tactile exploration of molecules. A deep understanding of inter-molecular forces that govern the binding processes is fundamental in chemistry teaching. From a research point of view, interactions among molecules can be described only as huge sequences of data, which determine how the attraction/repulsion forces take place and, as a consequence, determine also which are the positions of binding sites on the molecular surfaces. This huge amount of data is awkward to be interpreted even by experts of the field. Haptic interaction can greatly help in this context, because the forces involved in the chemical interactions can be directly felt through an haptic device. At this aim we have developed a virtual environment for molecular exploration, where a visual representation of a molecule is shown to the user, and the electrostatic surface and its influence on the surrounding space can be explored to better understand of inter-molecular phenomena. The user can move the haptic probe of a Sensable PHANToM device, and use it as a pointy cursor, in the virtual environment. The cursor of the probe can be associated with an electric charge, set either with positive or with negative values. While navigating the 3D space around the molecule, the user gets the feeling of the forces of the electrostatic interaction between the charge and the molecule.
The haptic interaction is enriched with auxiliary information to help navigation and comprehension of the related concepts. These additional information consist in the visualization of the geometrical representation of the molecule using one of the typical molecules representation adopted in chemistry (e.g., ball-n-stick, van der Waals spacefil, etc.), or in the coloring of the molecular surface with difference colors in order to highlight the sign of the potential values and their magnitudes; these information can be used to determine which are the areas of the molecular surface that can attract / repulse the electric charge.
Moreover, the plot of the electrostatic potential in the direction connecting the molecule ad the haptic proxy. The plot is useful because it allows to highlight the position of minimum potential surface, which are a fundamental information in ligands creation; its position in space is also a key information because it allows to determine what is defined as "ligand distance" in chemistry textbooks.
We have proposed activities with the developed tool to be performed in parallel to a curricular chemistry course offered at a university level. The features of the tool allow to experience some usual topics of a basic chemistry course, such as molecular polarity, critical points detections (minima, maxima) and ligand distance, and molecular anisotropy (i.e., different force w.r.t. the direction of approaching). Users' feedbacks have been gathered about the introduction of this tool: they reported an improved knowledge of covered topics w.r.t. the degree of knowledge on the same topics before the activity, and they appreciated this new method of teaching.

Keywords:

Haptics, Chemistry education, Virtual laboratory, Learning.