Auxetic materials: Functional materials and structures from lateral thinking!

Review: Materials that become thicker when stretched and thinner when compr essed are the subject of this review The theory behind the counterintuitive behavior of these so-called auxctic materials is discussed, and examples a nd applications are examined. For example, blood vessels made from an auxet ic material will tend to increase in wall thickness (rather than decrease) in response to a pulse of blood, thus preventing rupture of the vessel (see Figure).