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Morphable 3D mesostructures and microelectronic devices by multistable buckling mechanics
Reconfigurable electronic devices that can be shaped in two or more stable geometries modifying their functionalities have been realized, as highlighted by the Cover of March 2018 Issue of Nature Materials.
3D structures capable of reversible transformations in their geometrical layouts have important applications across a broad range of areas. Most morphable 3D systems rely on concepts inspired by origami/kirigami or techniques of 3D printing with responsive materials. The development of schemes that can simultaneously apply across a wide range of size scales and with classes of advanced materials found in state-of-the-art microsystem technologies remains challenging. Here, we introduce a set of concepts for morphable 3D mesostructures in diverse materials and fully formed planar devices spanning length scales from micrometres to millimetres. The approaches rely on elastomer platforms deformed in different time sequences to elastically alter the 3D geometries of supported mesostructures via nonlinear mechanical buckling. Over 20 examples have been experimentally and theoretically investigated, including mesostructures that can be reshaped between different geometries as well as those that can morph into three or more distinct states. An adaptive radiofrequency circuit and a concealable electromagnetic device provide examples of functionally reconfigurable microelectronic devices.
Read the article: Nature Materials 17, 268-276 (2018) (Cover Feature Article)
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Material Properties Across Size Scales
Hello
This is very interesting research. What are your observations on the impact of material properties as various size scales on elastic performance, and especially related to non-linear buckling criteria? I am interested your thoughts on challenges/opportunities based on changes in homogeneity, defects, grain size, etc..., as scale changes.
In general, do you feel standards in fabrication would help to accelerate small scale system development? Does each method need its own test properties?
Thank you for your time.
Regards,
Luke Porisch
St. Ansgar, IA
Reply to Comment "Material Properties Across Size Scales"
Hello Luke Porisch,
Thanks for your kind words and questions! In our study, the loading was applied to the thin-film structures through the elastomeric substrate by controlling the biaxial prestretching, which can be understood as a type of displacement loading. In this condition, the non-linear buckling behavior is not very sensitive to the elastic properties of the materials, if the thin-film structure is relative homogenous.
In this NAT MATER paper, we considered silicon and polymeric thin films with the thickness ranging from around 1.5 micron to 50 microns. In this range, the change of material properties induced by the size effect seems not so prominent, which is evidenced by the agreement between the measured 3D configurations and FEA calculations based on homogenous thin-film models with elastic properties equal to their bulk material. It can be expected that the mechanical properties (e.g., elastic modulus and ductility) might change due to the inhomogeneity, defect, and other effects, as the size goes down further, e.g., below 100 nm. When the feature size of inhomogeneity is comparable to the lateral (or in-plane) dimensions of the thin-film structures, then I would expect this effect to have an impact on the buckling process.
Yes, the standards in fabrication would be helpful in the development of small scale system, in my opinon. It might depend on the specific principles of different methods, but each method might generally need its own test properties. Not sure.
Best regards!
Yihui