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Page 10 of 31 Lee et al. Soft Sci 2024;4:38 https://dx.doi.org/10.20517/ss.2024.36

Figure 8. Flexible films with multi-directional stretchable Kirigami patterns. (A) Kirigami sheet with stress-strain characteristics
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programmed based on the parameters of the cut patterns and the thickness of the film. Reproduced with permission . Copyright 2019,
Wiley-VCH; (B) Pneumatic actuator with pre-programmed motion capabilities using a composite Kirigami-patterned substrate.
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Reproduced with permission . Copyright 2021, Khosravi, Iannucci and Li; (C) Mechanical deformation of Kirigami sheets resulting
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from various combinations of cut patterns on a square flexible sheet. Reproduced with permission . Copyright 2017, American Physical
Society; (D) Tensile deformation of Y-cut PET film and application of a textile sensor patch, developed based on the designed film, to a
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bent elbow. Reproduced with permission . Copyright 2019, Association for Computing Machinery. PET: Polyethylene terephthalate.
not only offers a straightforward approach to producing Kirigami sheets but can also be combined with
optimization techniques to design perforation patterns that generate complex shapes under external loads.
This approach can be applied to create Kirigami sheets across various scales, from transformable meter-
scale structures to tunable nanoscale surfaces, providing a simple way to manufacture complex, morphable
structures from flat perforated sheets. Additionally, Groeger et al. ingeniously combined Y-shaped cut
patterns to develop a PET film with significantly enhanced adhesion to complex curved surfaces
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[Figure 8D]. The Y-shaped cut pattern, created through laser patterning, provides anisotropic stretchability,
allowing the film to flexibly adapt to intricate skin contours and dynamic movements. This pattern evenly
distributes the stress generated when the film stretches, ensuring structural stability. As a result, the film
adheres securely to the skin, even during user movement, making it ideal for applications such as E-skin
and wearable devices.