Geckos adhere to smooth surfaces due to what forces generated by their toe pads?

Geckos adhere to smooth surfaces due to what forces generated by their toe pads?

• A. Capillary suction
• B. Magnetic attraction
• C. Electrostatic attraction
• D. van der Waals forces generated by setae.

Answer: (D)

Gecko adhesion is driven by many tiny van der Waals interactions generated by hair-like structures on the toe pads. The pads are covered with countless microscopic hairs called setae, and each seta splits into nanoscale spatulae that press against the surface. This creates an enormous number of contact points, so the weak van der Waals forces from each point add up to a strong overall adhesion that can support the gecko’s weight on smooth surfaces. This mechanism works on dry surfaces and allows easy detachment when the gecko wants to move.

Other forces listed aren’t the primary cause here: capillary suction would require a liquid film, magnetic attraction would need magnetic materials, and electrostatic forces are not the main adhesive mechanism—van der Waals forces generated by the setae are.