3D-printed Millimeter-sized Robots

An exciting (and lovingly detailed) paper in Science Robotics documents the design and production of Millimeter-scale flexible robots with programmable three-dimensional magnetization and motions for use in hard-to-reach body parts and possibly surgery as well. Developed by researchers in the University of Toronto, the tiny little device is activated by a magnetic field:

As in all the best papers, this one show materials and methods in exquisite detail, illustrating the physical apparatus for patterning the magnetic needles which make up the basic structure of several tiny machines: the millimeter-scale segmented magnetic swimmer, the untethered multi-arm magnetic microgripper, and the multi-legged paddle-crawling robot.

What’s really wonderful about this paper is the careful explanation of the first principles used to build up all the other pieces (see Table 1., where they show the reason they are able to successfully manipulate in three dimensions using only a single magnetic field).

Table 1. Capabilities of major existing methods to pattern magnetic particles. 1D: Only binary magnetization can be patterned, e.g., longitudinal or perpendicular recording in a hard disk drive. 2D: Direction of magnetization in each layer is restricted to a single plane. 3D: Magnetization in each layer can be patterned in arbitrary direction. Discrete: Magnetization in each area is independent of adjacent areas. Continuum: Magnetization in each area cannot have sudden changes with respect to adjacent areas. N/A, not applicable.

*Shape of media refers to the structure of the composite materials in which the magnetic particles are dispersed. 2D refers to planar structures, whereas 3D refers to solid 3D structures.

†States of magnetization is defined as degrees of freedom related to the orientation of hard magnetic particles or preferred magnetic axes of soft magnetic particles in each area.

 

Beautiful. The rest of the paper is just as detailed, and even fairly easy to understand.

 

Homework: T. Xu el al., “Millimeter-Scale Flexible Robots with Programmable Three-Dimensional Magnetization and Motions,” Science Robotics (2019). robotics.sciencemag.org/lookup … /scirobotics.aav4494