We have a portable Phenom G2 Pro desktop Scanning electron microscope that we’ve been bringing to schools and museums for demos and fun science activities.
Have a look at our past fun days and contact us if you’d like to plan future activities for your students!
Butterfly Festival – University of Michigan Museum of Natural History (May 2017)
The Michigan Center for Materials Characterization, known as (MC)2 recently took part in a joint outreach and educational activity with the University of Michigan Museum of Natural History. For each of the last few years, the museum has held a Butterfly Festival. At this event, held this year on the 12th and 13th of May, visitors to the museum learn about the life cycle of various butterflies and are able to interact with a large number of these insects and feed them nectar in a custom enclosure constructed in one of the education rooms inside the museum. This year John Mansfield, from (MC)2, joined staff of the museum to introduce visitors to the different ways butterflies exhibit color in their wings.
The color of butterfly wings can be very striking. Their colors are often very strong and yet also appear to change when they are viewed from different angles. Although the colors may look like they simply come from strong color pigments in the thin wings, the actual source of the colors and their iridescence are complex. The colors that we see come from complicated chemical pigments and intricate structural features in the sub-micrometer structures of the insect’s wings. The color pigments comprise of chemical components that absorb certain wavelengths of light and reflect others and this results in the basic colors that are observed. However, there is a second source of color, called structural color, which results from the microstructure of the wings. It is termed microstructure because the features we are describing are often smaller than one millionth of a meter, that is one thousand times smaller than a millimeter, which is the smallest division on a metric ruler.
Each butterfly wing is covered in many hundreds of tiny scales which are layered on top of each other. The tiny filaments that make up the smallest parts of the scales are separated by varying distances and these distances are small enough to selectively scatter certain wavelengths (colors) of light. The features on the scales are fixed, however, when the butterfly moves its wings, the amounts of light scattered vary and so the colors are observed to change or shimmer. The features on the wings are so small that Dr. Mansfield used a portable scanning electron microscope (SEM) to show visitors the features. They first observed the butterfly scales in the museum’s stereo optical microscopes and then zoomed into the fine details on the scales to see the light scattering features in the SEM.