Figure 5
From: Biaxial stress controlled three-dimensional helical cracks
Helical cracks with controllable numbers of coils and the manufacturing of a microspring. (a–d) Helical cracks with 1, 4, 9 and 14 coils, respectively, demonstrating the high reliability and controllability of the biaxial stress fracture technique. (e) Direct proportion relationship between the length–diameter ratio of the spindle knot (x/y) and the number of helical coils. (f) Creation of a microspring through the removal of the core material. Scale bars=20 μm.
