Researchers in biomedical applications have long had interest in the creation of smaller, softer, safer and more intelligent robots . The development of both micro-electro-mechanical system (MEMS) and nanotechnology have made great strides in building smaller robots . However, these micro/nano devices are generally made of silicon or metallic materials, whose intrinsically inflexible properties restrict the transformation of microrobots and pose potential threats for medical applications to a significant degree. Current progress in developing soft and smart materials such as stimuli-responsive hydrogel and shape memory polymer enables us to devise micromachines that can perceive external environments and respond with programmability through the conventional manufacturing techniques of MEMS. Using Origami/Kirigami design principles as a framework, we can establish complex three-dimensional (3D) microstructures employing self-folding polymer films . This programmable matter allows a single machine to transform into multiple folding forms.
Here, we utilize magnetic hydrogel nanocomposites as programmable matter to construct microrobots that emulate the forms, locomotion, and morphological plasticity of various microorganisms. We encode and recode the 3D forms, magnetic anisotropy, and locomotion of the flexible microrobot powered and propelled by external magnetic fields, and then observe and study its motility and maneuverability in a non-structural, heterogeneous, and dynamically changing environment. Using acquired knowledge on microrobot locomotion with various forms in different environments, we encode the morphological adaptation of a transformative microrobot. The microrobot is able to change its form autonomously to optimal locomotion in diverse environments. The coordination between sensory input and transformation output is the key to achieving adaptive locomotion. This study provides a reference for autonomous targeted therapies using smaller, softer, safer and more intelligent robots.
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 H.-W. Huang, M. S. Sakar, A. J. Petruska, S. Pane, and B. J. Nelson, “Soft micromachines with programmable motility and morphology,” Nat Commun, vol. 7, 2016.