Post-it notes are very popular among students, teachers, researchers, workers, etc because of its usefulness and convenience of helping its user remember important things. Post-its, however, tend to fall off when wet (at least when the glue gets wet). In the original article, it described the motivation of scientists to find a substance that could make even the wet post-its stick. Their idea stemmed from the fact that spiders stick to ceilings and there must be a substance in the spider’s legs to make them stick to a surface.

Spiders, like any other insects, can be viewed under any types of microscopes like a biological monocular microscope. Biological monocular microscopes contain only one eyepiece. Magnifications of up to 1000x can be used with biological monocular microscopes.

Using microscopes, like biological monocular microscopes, a research team found out that a molecular force makes a spider stick to almost anything. It was the first time, according to the original article, that a study on the exact measurement of the adhesion forces and how spiders stick was made. An image of a foot of a specific species of spider was taken with a scanning electron microscope. It was thru this image that they found out that aside from the tuft of hairs on the bottom of each spider’s leg, each individual hair was covered with smaller hairs called setules. The setules are what makes a spider stick.

In the original article, the research team named the molecular force that makes spider stick as the van der Waals force. This force acts between different molecules that have a distance of less than or equal to a nanometer of each other. How small is a nanometer? It is about ten thousand times smaller than the width of a human hair! Using biological microscopes and a technique called atomic force microscopy, researchers are able to measure this force. The setules of the legs of a spider have flexible contact tips that are triangular and have an increased adhesive force on the surface they are in contact with. There are about 600,000 setules in a spider’s foot. The total adhesive force for the spider will be 170 times its weight!. The interesting thing about the van der Waals force is that the force is not affected by the external environment. It is only affected by the distance between the two objects that are in contact.

Van der Waals force is the result of the movement of atomic articles making them dipolar. A dipolar has two poles, positive and negative. The negative pole will be attracted to the positive pole and vice versa. It is similar to the magnetic attraction between the north and south poles of a magnet.

There are many applications for the van der Waals force: Post-it notes that is still sticky even when it is wet or greasy or even space suits for astronauts that could help make them stick on the spacecraft’s surface. The result of this basic research can pave the way to more ground-breaking technology. Original article can be found here