Layered assemblers for scalable parallel integration

Abstract

Many complex natural and artificial systems are composed of large numbers of elementary building blocks, such as organisms made of many biological cells or processors made of many electronic transistors. This modular substrate is essential to the evolution of biological and technological complexity, but has been difficult to replicate for mechanical systems. This study seeks to answer if layered assembly can engender exponential gains in the speed and efficacy of block or cell-based manufacturing processes. A key challenge is how to deterministically assemble large numbers of small building blocks in a scalable manner. Here, we describe two new layered assembly principles that allow assembly faster than linear time, integrating n modules in O(n^2/3) and O(n^1/3) time: one process uses a novel opto-capillary effect to selectively deposit entire layers of building blocks at a time, and a second process jets building block rows in rapid succession. We demonstrate the fabrication of multi-component structures out of up to 20 000 millimetre scale spherical building blocks in 3 h. While these building blocks and structures are still simple, we suggest that scalable layered assembly approaches, combined with a growing repertoire of standardized passive and active building blocks could help bridge the meso-scale assembly gap, and open the door to the fabrication of increasingly complex, adaptive and recyclable systems.

Keywords: digital fabrication; layered assembly; multi-material printing; self-alignment; self-assembly; voxel printing.

Figure 1.

Layered assembly. (a) A meso-scale assembly gap currently exists between deterministic top-down assembly methods and bottom-up self-assembly. (b) A layered assembler (centre) arranges raw building blocks into the desired object. Here, a rook shape composed of several thousand spherical elements is specified electronically (left) and assembled into a physical object (right).

Figure 2.

Parallel-layered assembly using spherical elements. (a) Prefabricated elements of multiple materials are poured into feeders and self-align into an ordered lattice. (b) A projector selectively activates the desire cells on the wetted deposition tool by drying unwanted cells. (c) The head is pressed against the lattice and all wetted regions pick up elements simultaneously and deposit them on the build stage (d). Steps A through D are repeated for each material of each layer. Once the entire object is assembled (e), sacrificial support material may be removed to create freeform geometry (f).

Figure 3.

Examples of objects built by layered assembly: 1.5 mm spherical elements of multiple materials are assembled into a stable three-dimensional lattice such as (a) a 22 000 element structure. Selectively bonding elements enables freeform shapes such as a knight (b) and rook (c). Other material and post-processing combinations result in a freeform stainless steel structure (d), a brass and stainless steel structure (e) and a copper–nylon structure which forms a simple electrical network (f).