How Do You Find Beauty In a Ferrofluid?

A chemist and a photographer shed new light on spectacular surfaces

George Whitesides knew he needed better illustrations for his scientific papers. But the Harvard University chemistry professor wasn't prepared for the critique he got from professional photographer Felice Frankel.

"She made rude remarks about the technical quality of the photos," jokes Mr. Whitesides. The artwork accompanying his papers was awful, she told him, and typical of a scientist: black-and-white photos that were out of focus and contained little information to help the reader better understand the science.

Their subsequent collaboration not only changed the way science can be seen through the camera lens, it altered how these scientists conducted their experiments to make them more image-worthy.

"We are required as scientists to think about the experiment in terms of color or patterns, which requires us to have a larger degree of control," Whitesides said during a recent interview, along with Ms. Frankel, in his office at Harvard. "The combination of words and pictures conveys a staggering amount of information."

Initially, their work appeared in the journal Science. Now it's exhibited in "On the Surface of Things: Images of the Extraordinary in Science," published this month by Chronicle Books.

Scientific peers call the volume a union of art and science. Whitesides and Frankel see their work as an educational effort to make scientific phenomena more understandable by using striking photos that grab the eye.

The book combines poetic text by Whitesides with photographs from Frankel that are reminiscent of paintings by Georgia O'Keeffe or Dutch artist Piet Mondrian. Three years in the making, the effort focuses on activities on surfaces, from why adhesives fail to hold to why a film of liquid remains continuous or breaks into drops, a phenomenon that can make contact lenses fit more comfortably or ensure that paint covers a surface evenly.

Frankel and Whitesides met while Frankel was on a fellowship at Harvard in 1991. A landscape architecture photographer with an undergraduate degree in biology, Frankel attended Whitesides class. The two soon began discussing how to better relate science to the public.

"We're both trying to communicate the same ideas," says Frankel, who has had a longtime interest in science. "I'm just doing it visually." Frankel currently is an artist-in-residence and research scientist at the Edgerton Center of the Massachusetts Institute of Technology.

"We enjoy working together, and it was enormously instructive," Whitesides says. "I know science, so it was very interesting for me to learn how to explain it to Felice. It was the mirror of her working with me on the images."

The first joint effort by the two was the Sept. 4, 1992, cover of Science. Whitesides wanted to show the importance of controlling the spread of liquids on surfaces, a phenomenon that is important in printing, mammalian cell functions, and fabricating various electronic devices for computers and cars.

Painting stripes of molecules

To make the point, Nicholas Abbott, who was a postdoctoral fellow at the time in Whitesides' laboratory, worked with Frankel to create square drops of water. Water normally beads into circular drops on a surface. But the scientist was able to make a grid of square drops by coating a surface with a single layer of molecules that attract water, and then breaking that surface into squares by painting stripes of molecules that repel water. The result: The molecules of water crowded to the edges of the stripes, producing square drops.

For the photograph, fluorescent dyes were added to the water to emphasize the shape of the drops. Frankel used a Nikon F-3 camera with a 105-millimeter macro lens on a tripod to photograph the grid of square drops. She added warm tungsten and ultraviolet lights to deepen the coloration of the blue and green squares.

"We wanted to make something interesting to look at, to invoke curiosity and get the reader interested in the content," Whitesides says. "The colors made a more interesting picture with a lot more information than a black and white photo."

Both Whitesides and Frankel caution that it is important not to sacrifice accuracy for artistry. Frankel submitted five photos to Science. Her favorite, showing two-tone square drops, was rejected because the extra colors made it appear as though another phenomenon was at work.

A few other books attempt to illustrate science, such as "Chemistry Imagined," a collaboration between Cornell University chemist Roald Hoffmann and artist Vivian Torrence, and "Art and Science: Investigating Matter," by photographer Catherine Wagner, with text by an art curator and a philosopher. But members of the scientific community say that "On the Surface of Things" breaks new ground.

To Alan Lightman, an author and physicist at MIT, the volume "is at the very highest level of this genre."

"Each photograph is a work of art in itself," he adds. "And the text by Whitesides provides an important explanatory depth to the book, that there is physics, biology, and chemistry behind the pictures. This level of photography will be used more and more as a tool to convey science to the public."

Burkhard Bilger, deputy editor of The Sciences, the bimonthly magazine of the New York Academy of Sciences, agrees that "On the Surface of Things" is unusual in the high quality of its images. "The book is about images, so you see a lot of neat stuff. It is beautifully composed," he says.

Frankel says that making the photos relatively abstract and not self explanatory renders the text more provocative.

To capture the activity of ferrofluid - a dark brown liquid containing small pieces of iron - she dropped a few milliliters of the nondescript liquid onto a glass plate, which she placed on a yellow paper sitting atop seven circular magnets. Using a Nikon F-3 camera with 105-millimeter macro lens, she bounced the flash off of a green card to add color. The result: a Georgia O'Keeffe-like work of art with autumnal splashes of color.

Science behind the beauty

Coupled with the photo is Whitesides' flowing text explaining the science behind the beauty. On ferrofluids, he writes: "Pity the gryphon, the mermaid, the silkie, the chimera: creatures assembled of incompatible parts, with uncertain allegiances and troubled identities. When nature calls, which nature is it? When instinct beckons, approach or flee? A ferrofluid is a gryphon in the world of materials: part liquid, part magnet."

The science behind the photos is much broader than just the field of science depicted in them. The magnetic properties illustrated in the ferrofluid photo, for example, apply to devices where fluid properties and resistance to gravity are needed, such as rotary seals in computer disk drives and dampers for high-performance speakers.

Most of the work for the photographs - two weeks' worth per photo on average - comes before the actual shooting session, Frankel says. To produce an interesting picture, she and the scientist must collaborate closely to control the scientific effect, and then play with light and colors to turn it into an eye-grabbing photo.

About 100 scientists, mostly at MIT and Harvard, were involved in the research behind the book's photographs. Some of the photos required using a special attachment to hook the camera directly to a microscope. For "Failure in Adhesion," for example, Frankel slowly pulled a piece of transparent tape off of a silicon surface to show changes in the properties of adhesion where the tape and surface meet. Photographed under a microscope, the areas where the adhesive is broken create finger-like patterns.

A younger audience may soon benefit from such images, as Frankel hopes to produce a book for children. "My goal is to get people turned on to science," she says.

'Failure in Adhesion'

"Sticking" has two parts: the liquid that is sticking and the surface being stuck to. Water is easy to wipe from the floor. Viscous liquids are difficult to remove: honey resists wiping; road tar refuses. The nature of the surface is important, too: nothing sticks to Teflon; everything sticks to an expensive suit.

An adhesive is a viscous liquid (so viscous it may be solid) that sticks well to surfaces being glued. The most important factor in sticking is the surface. Surfaces that are wetted well by liquids - surfaces whose atoms wish to be covered by other matter - are easy to glue; ones whose surface atoms are indifferent to their exposure are more difficult.

When an adhesive fails - when the glue breaks - it can do so in many ways. The film of liquid adhesive can pull apart, like tearing chewing gum. The interfaces between the adhesive and the glued surfaces can fail. If the adhesive bond is very strong, the objects that are glued together may simply fracture internally.

As this adhesive failed, the very viscous adhesive liquid began to peel back from the surface, splitting into "fingers" that remained stuck to the surfaces, and the adhesive remaining in the fingers moved together laterally, perpendicular to the line of the retreating liquid.

- By George Whitesides

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