Virtual Reality for Teaching

Several preliminary Virtual Reality (VR) interactive games/demonstrations have been prepared to improve student engagement in engineering and science topics. Thus far, these cover the topics of electron conduction in pn-junctions, photoconductivity, thermal excitation, the operation of an Atomic Force Microscope (AFM) for nanoscale surface measurements and manipulation, and our (in)famous group holiday card presenting Atomic Force Snowman Microscopy. More sophisticated demos could effectively present a range of scientific and technological concepts at a variety of skill levels to enhance engagement in, and access to, these and other topics relevant to devices we use in everyday life (computers, mobile phones, etc.). Instructions to freely download and use the programs are simple.

Electron conductivity in biased pn junctions

Semiconducting pn-junctions are crucial to the operation of computers and many other modern electronic devices. To learn more about them, explore a junction from the perspective of an electron. Using the space bar, inject electrons into the n-doped side of a semiconductor pn-junction, and with the up and down arrows modify the voltage applied across the junction. For forward biases, electrons can pass the decreased barrier at the p-n interface, whereas for reverse biases the barrier increases and conduction evidently does not occur. The red/yellow/green indicator is a useful guide for knowing if you have biased the junction sufficiently. Different perspectives are accessible using the function keys.

Photoconductivity

The principal of photoconductivity is central to the operation of many optical sensors, including thermal and imaging detectors and cameras. To explore photoconductivity at the lever of an electron, select a color of light (remember energy relates to color) and blast away at the electron thermally vibrating at the valence band edge by hitting the space bar (left and right arrows aim your laser gun). If you hit the electron with enough energy (an appropriate color), the electron can be excited across the bandgap to the conduction band above and carry current. Again, different perspectives are accessible using the function keys.

Thermal Excitation

Free carriers in a semiconductor are critical to their application. As the temperature increases, more and more electrons in the valence band have enough energy to jump to the conduction band and carry current. Animations allowing users to adjust the temperature and monitor these thermally activated intrinsic carriers are being prepared.

Virtual Reality AFM

Virtual reality (VR) software has been used to create an educational demonstration about Atomic Force Microscopy, a tool for studying and modifying surfaces at the nanoscale. In an AFM, a sharp tip is dragged or tapped across a surface. Note the roughness of the surface as you manipulate the AFM tip and attached cantilever around a 5 micrometer section of a surface (1/10 the width of most human hair). The corrugations you ‘see’ from the perspective of the tip itself are only 5 nanometers tall, 1/10,000^th of the width of your hair.

• A 3-d animation of an AFM tip scanning a rough surface has been generated (based on real AFM data).
• A VR-AFM game has been developed that allows 2 users to control 2 distinct AFM cantilevers/tips as they bounce around a real surface with real topography (ac-mode AFM).

Game Commands:

• The up, down, left, and right arrows move the gold lever and tip up or down and rotate left or right, respectively.
• The keys w, s, a, and d control the other tip in the same manner.
• Buttons F1, F2, F3, and F4 switch perspectives from following the gold lever, following the other lever, first person gold tip, and first person gold lever, respectively. Keys F5, F6, F7, and F8 switch to static cameras providing ‘ringside,’ oblique, top-view, and other views.
• There are sounds, so adjust your speakers.
• The demo may be used for lever/tip duels (try to push the other lever out of the ring).
• If both cantilevers fall out of the ring, it is best to close the window and restart the executable.

Atomic Force Snowman Microscopy (AFSM)

• This holiday version of VRAFM (2005/06) allows an AFM tip to scan alongside a scanning snowman featuring a carrot nose for a tip (and two eyes made out of coal…). An animation of this FPS game (first person snowman) is available as well.

Game Commands:

• Same as for VR-AFM, but one of the tips is a snowman!

Instructions

Free Installation:

• Follow the links above and extract the zipped folder anywhere onto your computer from the .zip file (<3 MB)
• This folder contains the executable demo, 2 support files (.dll, common to all of the demos), and a nested folder (‘textures’) which includes images and sound files required for the main program.
• Double click on the executable (.exe).
• Close the program by closing the operating window.
• Note: To uninstall, simply throw away the entire folder. The programs do not modify any hidden directories, system settings, or folders, and do not install anything onto your computer other than a single copy of the files exactly where you specify.

Please recognize the UConn HueyAFMLabs if you use these demonstrations beyond personal use.

-Bryan Huey