In this blog post, we’ll explore how the van der Waals forces generated by a gecko’s setae and spatula-shaped cilia are being applied to biomimicry technology and inventions like the StickyBot.

Nature’s Adhesive

Let’s recall a scene from a movie. With time running out, the protagonist puts on a pair of gloves—a new invention—handed to him by a colleague. The colleague explains that the gloves have enough adhesive power to keep a person stuck to a slippery glass wall, but the protagonist is anxious because the equipment hasn’t been tested yet. Eventually, to reach the mission site quickly, the protagonist must travel along the building’s exterior, and while climbing the glass wall wearing the gloves, a malfunction occurs, leading to a hair-raising situation.
Scenes like this spark the audience’s scientific curiosity. Can humans really climb glass walls freely, just like the invention in the movie? If so, dangerous work at heights could be performed more safely, and climbing rugged cliffs with ease would become a reality. Fortunately, this isn’t just a distant sci-fi fantasy. We can already commonly see small insects crawling up walls around us, and we can find the answer in them.
In fact, there are many small creatures around us that crawl up walls and cling to ceilings. At first glance, it’s easy to assume this is simply because they are small and light, but curious scientists have focused on the structure of their feet and discovered the evidence through microscopic observation. In 1664, the British experimenter Henry Power claimed that a fly’s ability to adhere to surfaces was due to a viscous liquid secreted from its legs, but a year later, Robert Hooke refuted this, arguing that the cause was the fine hairs on the fly’s legs. Since then, the adhesive abilities of insects and lizards have attracted significant attention as intriguing characteristics that humans have sought to apply.
If we look around again, we see many small animals—such as ants, centipedes, and flies—that move effortlessly along walls. Scientists examined their legs closely and confirmed that their microstructure is closely related to their adhesive properties. In other words, the debate between the two early interpretations of the adhesion phenomenon—the viscous fluid theory and the fine-hairs theory—was ultimately resolved by evidence showing that microstructure and physical forces play a crucial role.
The Stickybot, developed at Stanford University in the United States in 2006, garnered significant attention as a representative biomimetic robot modeled after the structure of a gecko’s feet. The Stickybot attracted interest due to its ability to climb glass walls. Even recently, various research projects and technological developments mimicking the structure of a gecko’s feet have been continuously underway.
Geckos freely climb up and down trees, rocks, and building walls to catch insects, and they possess a unique foot structure that makes this possible. According to studies published in the early 2000s, the gecko’s adhesive force is known to rely heavily on Van der Waals forces. The soles of a gecko’s feet are covered with numerous microscopic hairs called setae, and these hairs generate adhesive force through Van der Waals forces.
Van der Waals forces are weak attractive forces that occur when very small particles, such as atoms or molecules, come into close proximity. A temporary imbalance in the distribution of electrons within an atom creates a transient polarity, which in turn generates a force that attracts it to nearby particles. This force is highly distance-sensitive; it weakens rapidly even with a slight increase in distance, so it has a meaningful effect only at extremely close ranges.
A closer look at the structure of a gecko’s foot reveals millions of microscopic hairs, each about 5–10 μm in diameter. These hairs, in turn, branch into spatula-shaped cilia (spatulas) approximately 1–2 μm long and 200–500 nm in diameter. Considering that a single water molecule is about 0.1 nm in size, these cilia are extremely small structures—nearly at the molecular level—and can therefore be effectively influenced by van der Waals forces.
Although van der Waals forces themselves are very weak, this is not a major issue. Think of the static electricity that causes your hair to stick to you when you take off a sweater in winter. The force acting on a single strand of hair is weak, but when countless strands are subjected to the same force in the same direction simultaneously, the cumulative effect is significant. Similarly, while the force generated by an individual gecko hair is small, millions of hairs acting simultaneously create enough adhesive force to support the gecko’s body weight.
However, simply sticking well isn’t enough to move freely. The ability to easily detach from a surface is also essential. The key lies in the shape and angle of the trichomes. The spatula-shaped structure at the tip of each trichome is designed to increase or decrease the contact area. When the trichomes stand vertically, the contact area is small and the adhesive force is weak; however, when they are pressed downward as if being pulled, the contact area widens, causing the van der Waals force to increase significantly. Conversely, by adjusting the angle of the toes to reduce the contact area, the gecko can detach easily. In other words, the gecko freely controls the attachment and detachment process by adjusting the angle and applying shear force.
Robots such as the StickyBot were developed by applying this principle. The StickyBot demonstrated the ability to climb glass walls by mimicking the gecko’s trichome mechanism. In Korea as well, research aimed at mimicking the gecko’s adhesive capabilities has been steadily conducted since the 2000s, primarily at universities and research institutions. Various practical technologies are being researched, such as methods for moving semiconductor wafers without using mucus or hooks and without scratching the surface, as well as the development of medical bandages and tapes that reduce skin damage caused by conventional adhesives.
As such, biomimetic technology—which mimics small structures found in nature—is already yielding results in various fields and is highly likely to be utilized in even more industrial sectors in the future. Even if a device identical to the gloves seen in movies does not appear immediately, adhesion technology based on the gecko’s foot structure continues to expand into practical applications, such as improving safety in dangerous high-altitude work, enhancing robots’ mobility, and developing non-damaging adhesives for medical and industrial use.

The Connection Between the Gloves in the Movie and Reality

Let’s recall a scene from a movie. The protagonist, racing against time, puts on a pair of inventive gloves handed to him by a colleague and attempts to climb a glass wall, but a malfunction in the equipment leads to a hair-raising situation. Watching this scene, audiences are left wondering, “Can a person really stick to a glass wall and climb it?” If this were possible, it would bring about major changes in various fields, such as ensuring safety during high-altitude work and rock climbing.
This imagination isn’t just a story of the distant future. Creatures that crawl on walls, such as small insects and geckos, already exist, and inventions with similar capabilities are becoming a reality through biomimicry technology inspired by them.

The Gecko’s Adhesion Principle and the Stickybot

Developed at Stanford University in 2006, the Stickybot is a robot modeled after a gecko, designed to climb smooth surfaces such as glass. Geckos freely climb up and down trees, large rocks, and building walls to catch their prey, thanks to the unique microstructure of their feet.
The adhesive force on a gecko’s feet relies heavily on van der Waals forces. Van der Waals forces are weak attractive forces that arise momentarily when small particles, such as atoms or molecules, come into close proximity; they are formed by a temporary shift in electron distribution. Because these forces are highly sensitive to the distance between particles, they are effective only at extremely close ranges.
The gecko’s feet are densely covered with millions of microscopic hairs, each 5–10 μm in diameter; these hairs are further divided into spatula-shaped cilia measuring 1–2 μm in length and 200–500 nm in diameter. Considering that water molecules are about 0.1 nm in size, these cilia are close to the molecular scale and are therefore highly susceptible to the influence of van der Waals forces.
Although van der Waals forces are very weak on their own, when millions of contact points act simultaneously, they generate a very strong overall adhesive force. This is similar to the phenomenon where numerous electrically charged hairs, when acting together, generate a force greater than one might expect.
In addition to adhesion, the ability to detach easily is also important. The tips of a gecko’s filaments are spatula-shaped and split into multiple prongs; while the contact area is small under normal conditions, applying downward pressure to press them against a surface increases the contact area, thereby enhancing adhesion. Conversely, changing the angle reduces the contact area, allowing for easy detachment. Thanks to this angle-adjustment mechanism, the gecko can achieve both strong adhesion and effortless separation.

Research and Applications in Korea, and the Significance of Biomimetic Technology

In Korea as well, research aimed at applying the gecko’s adhesive capabilities is steadily progressing. For example, a domestic research team has developed an adhesive technology that leaves no scratches on surfaces without using mucus or hooks, demonstrating its potential for applications such as transporting semiconductor substrates. In addition, there is great potential for its use as a next-generation medical adhesive material that can reduce skin damage caused by conventional medical bandages and tapes.
Geckos are not the only examples; nature is home to many organisms that have adapted to their environments and possess unique abilities. Many of the solutions we need may already exist in nature. Biomimicry is the process of learning from and applying these natural designs, and through it, we can bring about practical changes in both daily life and industrial settings.