Adhesive material mimics the way geckos stick to surfaces

Scientists from the University of Massachusetts Amherst have invented a Gecko-inspired adhesive material.

The ‘Geckskin’ was developed after analysing how geckos adhere to walls.

Duncan Irschick, a biologist who has studied geckos’ climbing abilities for more than 20 years, said: ‘Amazingly, gecko feet can be applied and disengaged with ease, and with no sticky residue remaining on the surface.’

According to a statement, the researchers are aiming to take the same properties used by the gecko, such as high-capacity reversibility and dry adhesion, to develop materials that can attach objects, such as TVs, to a wall.

Alfred Crosby, the scientist who heads up the polymer science and engineering lab that the material was made in, said: ‘Our Geckskin device is about 16in² [387cm²], about the size of an index card, and can hold a maximum force of about 700lb [320kg] while adhering to a smooth surface such as glass.’

The material also enables devices to be easily released with little effort and can be reused many times with no reduction in performance. For example, it can be used to stick a 42in [107cm] TV to a wall, released with a gentle tug and re-stuck to another surface as many times as needed, leaving no residue.

Previous efforts to synthesise the adhesive qualities of gecko feet were focused on understanding microscopic hairs on their toes, called setae. However, attempts to translate these properties onto a larger scale were unsuccessful, in part because of the complexity of the entire gecko foot. Irschick explained in a statement that a gecko’s foot has several interacting elements, including tendons, bones and skin, that work together to produce easily reversible adhesion.

Geckskin and its supporting theory demonstrate that setae are not required for gecko-like performance. Crosby said: ‘It’s a concept that has not been considered in other design strategies and one that may open up new research avenues in gecko-like adhesion in the future.’ 

The key innovation was to create an integrated adhesive with a soft pad woven into a stiff fabric, which allows the pad to ‘drape’ over a surface to maximise contact. The researchers explained that, as in natural gecko feet, the skin is woven into a synthetic ‘tendon’, yielding a design that plays a key role in maintaining stiffness and rotational freedom.

Importantly, the Geckskin’s adhesive pad uses materials such as polydimethylsiloxane (PDMS), which holds promise for developing an inexpensive, strong and durable dry adhesive.

The researchers are continuing to improve their Geckskin design by drawing on lessons from the evolution of gecko feet, which show remarkable variation in anatomy. ‘Our design for Geckskin shows the true integrative power of evolution for inspiring synthetic design that can ultimately aid humans in many ways,’ said Irschick. 

The work was supported by the US Defense Advanced Research Projects Agency (DARPA) through a subcontract to Draper Laboratories, plus UMass Amherst research funds.