Selective Self-Assembly using Re-Programmable Magnetic Pixels

TL;DR

This paper presents a magnetic encoding method for physical modules that enables highly selective and re-programmable self-assembly into desired shapes, verified through experiments with cubic modules in water.

Contribution

It introduces a Hadamard matrix-based magnetic encoding technique for re-programmable, selective self-assembly of modules without geometric guides.

Findings

Successful self-assembly of 8 cubes in water

Modules can be re-programmed with a CNC magnetic plotter

Encoding guarantees attraction to intended mates

Abstract

This paper introduces a method to generate highly selective encodings that can be magnetically "programmed" onto physical modules to enable them to self-assemble in chosen configurations. We generate these encodings based on Hadamard matrices, and show how to design the faces of modules to be maximally attractive to their intended mate, while remaining maximally agnostic to other faces. We derive guarantees on these bounds, and verify their attraction and agnosticism experimentally. Using cubic modules whose faces have been covered in soft magnetic material, we show how inexpensive, passive modules with planar faces can be used to selectively self-assemble into target shapes without geometric guides. We show that these modules can be easily re-programmed for new target shapes using a CNC-based magnetic plotter, and demonstrate self-assembly of 8 cubes in a water tank.