Obtaining the maximum contact surface area between two substrates is one of the best understood ways to enhance adhesion them. Often the design and nature of adhesives means that they will automatically, perhaps even unstoppably, flow towards this goal. Now US researchers have developed polymers where the contact area with their substrate can controlled through exposure to an external stimulus – more specifically wrinkling in contact with water. They suggest that this technology could be used for tapes in biomedical applications. Potentially, they could even be used to produce bandages that adhere ever tighter the more blood they're exposed to and then become less adhesive as the bleeding wound heals.