Next Generation Colloidal Origami: Assembly of Directionally-Interacting Microcubes

North Carolina State University, Raleigh NC

Investigators

Abstract

This project involves the assembly of colloidal particles and aims to expand fundamental understanding in the making of reconfigurable and active "colloidal origami" structures. The team will establish the principles underlying the magnetic-field-driven assembly of microscopic cube-shaped units whose sequence encodes their function, capability and utility. The scientific knowledge gained could enable future fabrication of soft, shape-changing and stimuli-responsive materials based on origami particle networks. The broader fundamental understanding of these emerging active systems will make possible the design of new materials that could find application in microrobotic manipulators, soft actuators, devices for harvesting and redirecting energy on the microscale, and biomedical applications such as magnetically-stimulated bioscaffolds. The project will also assist in educating a new generation of undergraduate and graduate students in multidisciplinary topics ranging from classical chemical engineering to the emerging areas of active and reconfigurable materials. The research team's high school and community outreach activities will be enhanced through exciting hands-on demonstrations with visually-attractive models of magnetic microbots and origami. The broad range of educational and outreach activities will be aimed towards middle and high school students, undergraduates with diverse backgrounds and graduate students, especially those from underrepresented groups in STEM fields. The project will advance fundamental science by establishing the principles that govern how a new class of engineered materials - magnetically-polarizable, cube-shaped microparticles - interact, assemble, reconfigure and propel in response to external magnetic and electric fields. The microscale metallo-dielectric units that will be assembled possess a unique combination of exciting features: they can (1) interact in a directionally-specific and controlled way, (2) store energy from a magnetic field, (3) release magnetic energy through re-configuration, and (4) use external electric energy as a source of self-propulsion, making them "active" particles. A combination of experiment and modeling of the assembly processes will make it possible to understand and control the formation of micro-origami components for novel smart materials and gels with on-demand reversible phase transitions. The first objective of the project is to establish the fundamental principles of interaction-driven assembly for two classes of microcubes. The team will investigate the types of phases formed, their structures, connectivity, and ability to re-configure on demand. The second objective is to explore how adding particle motility modifies the structure and properties of the assembled phases. The hypothesis is that the dynamic motility of the active particles could be used to produce new types of highly interconnected structures. The third objective is to embed the responsive and reconfigurable "origami" structures into soft matter media, thereby demonstrating new field-responsive materials with unusual properties that can be useful for real-world applications. The project will assist in the multidisciplinary education efforts of the researchers and will enhance their outreach activities by developing of hands-on demonstration capabilities. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.