Figure 1. Illustration of a helix (top), a hemihelix with one perversion marked by an arrow (middle) and a hemihelix with multiple perversions (bottom).

The scale bar is 5 cm, and is the same for each image. These different shapes were all produced in the same way as shown in figure 2 with the same value of pre-strain but with decreasing values of the height-to-width ratio of the bi-strip's cross-section. , , ).