Animals
How Geckos Stick to Walls: Van der Waals Forces and Dry Adhesion
A gecko weighing 70 grams can hang from a ceiling by a single toe. The adhesive force available from its feet has been measured at approximately 20 Newtons — enough to support the weight of roughly 40 geckos simultaneously. No glue is involved. No suction cups. The mechanism is quantum-mechanical: trillions of nanoscale hair structures bring gecko toe pads into such intimate contact with surfaces that the quantum interactions between electrons in adjacent molecules provide enough combined force to defy gravity.