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Structures of thin films bonded on substrates have been used in technologies as diverse as flexible electronics, soft robotics, bio-inspired adhesives, thermal-barrier coatings, medical bandages, wearable devices and living devices. The current paradigm for maintaining adhesion of films on substrates is to make the films thinner, and more compliant and adhesive, but these requirements can compromise the function or fabrication of film–substrate structures. For example, there are limits on how thin, compliant and adhesive epidermal electronic devices can be fabricated and still function reliably. Here we report a new paradigm that enhances adhesion of films on substrates via designing rational kirigami cuts in the films without changing the thickness, rigidity or adhesiveness of the films. We find that the effective enhancement of adhesion by kirigami is due to (i) the shear-lag effect of the film segments; (ii) partial debonding at the film segments’ edges; and (iii) compatibility of kirigami films with inhomogeneous deformation of substrates. While kirigami has been widely used to program thin sheets with desirable shapes and mechanical properties, fabricate electronics with enhanced stretchability and design the assembly of three-dimensional microstructures, this paper gives the first systematic study on kirigami enhancing film adhesion. We further demonstrate novel applications including a kirigami bandage, a kirigami heat pad and printed kirigami electronics.
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Easy, Scalable, Robust, Micropatterned Silk Fibroin Cell Substrates
Abstract Thin polymeric films are being explored for biomedical uses such as drug delivery, biofiltration, biosensors, and tissue regeneration. Of specific interest is the formation of mechanically flexible sheets, which can be formed with controllable thickness for sealing wounds, or as biomimetic cellular constructs. Flexible substrates with precise micro‐ and nanopatterns can function as supports for cell growth with conformal contact at the biointerface. To date, approaches to form free‐standing, thin sheets are limited in the ability to present patterned architectures and micro/nanotextured surfaces. Other materials have a lack of degradability, precluding their application as cellular scaffolds. An approach is suggested using biocompatible and biodegradable films fabricated from silk fibroin. This work presents the fabrication and characterization of flexible, micropatterned, and biodegradable 2D fibroin sheets for cell adhesion and proliferation. A facile and scalable technique using photolithography is shown to fabricate optically transparent, strong, and flexible fibroin substrates with tunable and precise micropatterns over large areas. By controlling the surface architectures, the control of cell adhesion and spreading can be observed. Additionally, the base material is fully degradable via proteolysis. Through mechanical control and directing the adherent cells, it is possible to explore interactions of cells and the microscale geometric topography.
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- Award ID(s):
- 1704435
- PAR ID:
- 10461447
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials Interfaces
- Volume:
- 6
- Issue:
- 8
- ISSN:
- 2196-7350
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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