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Contributed by Yonggang Huang, February 3, 2021 (sent for review December 22, 2020; reviewed by Jerry Qi, Pradeep Sharma, and Yong Zhu)
Significance
The ability to miniaturize deployable and morphable structures could significantly broaden their applications in biomedical, healthcare, and electronics devices, but remains to be very challenging, due to the difficulty to achieve considerable actuation deformations at small scales (e.g., several millimeters). Here, we present actuation schemes and design strategies to enable assembly of three-dimensional (3D) mesostructures that actively, rapidly, and reversibly deform (by nearly an order of amplitude in size) and switch among various stable states. These schemes provide routes to multimodal devices that actively change their functions following changes in shapes. A skin sensor that can actively switch between the deep and shallow sensing modes serves as an example to demonstrate the promising potential toward developments of multimodal biomedical devices.
Abstract
Structures that significantly and rapidly change their shapes and sizes upon external stimuli have widespread applications in a diversity of areas. The ability to miniaturize these deployable and morphable structures is essential for applications in fields that require high-spatial resolution or minimal invasiveness, such as biomechanics sensing, surgery, and biopsy. Despite intensive studies on the actuation mechanisms and material/structure strategies, it remains challenging to realize deployable and morphable structures in high-performance inorganic materials at small scales (e.g., several millimeters, comparable to the feature size of many biological tissues). The difficulty in integrating actuation materials increases as the size scales down, and many types of actuation forces become too small compared to the structure rigidity at millimeter scales. Here, we present schemes of electromagnetic actuation and design strategies to overcome this challenge, by exploiting the mechanics-guided three-dimensional (3D) assembly to enable integration of current-carrying metallic or magnetic films into millimeter-scale structures that generate controlled Lorentz forces or magnetic forces under an external magnetic field. Tailored designs guided by quantitative modeling and developed scaling laws allow formation of low-rigidity 3D architectures that deform significantly, reversibly, and rapidly by remotely controlled electromagnetic actuation. Reconfigurable mesostructures with multiple stable states can be also achieved, in which distinct 3D configurations are maintained after removal of the magnetic field. Demonstration of a functional device that combines the deep and shallow sensing for simultaneous measurements of thermal conductivities in bilayer films suggests the promising potential of the proposed strategy toward multimodal sensing of biomedical signals.
- deployable and morphable 3D mesostructures
- Lorentz force
- magnetic force
- mechanically guided assembly
- instability
Footnotes
↵1F.Z. and S.L. contributed equally to this work.
- ↵2To whom correspondence may be addressed. Email: helingwang1{at}gmail.com, yihuizhang{at}tsinghua.edu.cn, or y-huang{at}northwestern.edu.
Author Contributions: H.W., Y.Z., and Y.H. designed and supervised the research; F.Z., S.L., and H.W. led the structural designs with assistance from H.Z. and Y.H.; S.L. and H.W. led the mechanics modeling and FEA predictions of reconfigurable mesostructures with assistance from Y.H.; F.Z. led the micro-fabrication work of mesostructures, with assistance from Z.S., X.C., and Z.X; F.Z., S.L., H.W., and Y.Z. led the device designs, electromagnetic modeling and analyses of thermal devices; F.Z. led the fabrication and experimental characterization of thermal devices, with the assistance from H.S., K.B., and D.Y.; F.Z., S.L., H.W., Y.Z., and Y.H., wrote the text and designed the figures. All authors commented on the paper.
Reviewers: J.Q., Georgia Institute of Technology; P.S., University of Houston; and Y.Z., North Carolina State University.
The authors declare no competing interest.
This article contains supporting information online at https://www.pnas.org/lookup/suppl/doi:10.1073/pnas.2026414118/-/DCSupplemental.
Data Availability
All study data are included in the article and/or supporting information.
Published under the PNAS license.
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Rapidly deployable and morphable 3D mesostructures with applications in multimodal biomedical devices
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