A potential remedy for injuries caused by slips and falls is literally right beneath us. The footpads of geckos possess hydrophilic (water-attracting) properties that enable these creatures to traverse wet and slippery surfaces effortlessly. According to researchers featured in ACS Applied Materials & Interfaces, they have successfully used silicone rubber mixed with zirconia nanoparticles to develop a slip-resistant polymer inspired by gecko feet. This innovative material, which adheres to icy surfaces, could be used in the soles of shoes to help prevent injuries among people.
According to the World Health Organization, slips and falls lead to over 38 million injuries and 684,000 fatalities annually, with almost half of these occurrences taking place on icy surfaces. Traditional anti-slip shoe soles often use materials like natural rubber that push away the thin layer of rainwater on wet pavement. However, on icy paths, these materials can inadvertently cause the ice to melt under pressure from the wearer, creating the very hazardous condition they are intended to guard against.
Prior research into gecko feet has sparked new strategies for creating more efficient anti-slip polymers. These studies revealed that the stickiness of the gecko’s footpads stems from a phenomenon called hydrophilic capillary-enhanced adhesion: the suction generated as water is drawn into the fine grooves of their pads assists the lizard in moving across slippery terrain. Researchers Vipin Richhariya, Ashis Tripathy, Md Julker Nine, and their team focused on creating a polymer that utilizes capillary-enhanced adhesion, making it effective on both wet sidewalks and icy surfaces.
The team began with a silicone rubber base and infused it with zirconia nanoparticles to enhance its ability to attract water. After shaping this composite material into a thin film, they solidified it through heating and then used a laser to etch a grooved design into the surface, revealing the hydrophilic zirconia nanoparticles. This resulted in a material that adhered to ice when it came into contact with water, effectively imitating the capillary action seen in gecko footpads. They evaluated five variations of this patterned nanocomposite, each varying in the proportion of zirconia nanoparticles (1%, 3%, 5%, 7%, and 9% by weight).
Through infrared spectroscopy and simulated friction testing, the researchers determined that the most effective slip-resistant nanocomposites were those with 3% and 5% zirconia nanoparticles by weight. Beyond developing anti-slip shoe soles inspired by nature, this technology has potential applications in medical advancements, such as electronic and artificial skin, where polymers interact with fluids between various surfaces.
The authors express their gratitude for the funding received from the Foundation for Science and Technology, Portugal.
