By Tucker Rae-Grant, Shuhong Wang, and Lining Yao . ACM CHI 2024 PDF | DOI

ExCell, short for Expanding Cellulose, is a water-activated wooden linear actuator that is simple to produce, simple to prototype with, and simple to understand.

While there has been sustained interest in shape-changing materials and deployable structures, many existing systems require engineering materials, precision fabrication, and computationally modeled kinematics in order to work. Additionally, many rely on external power sources in order to deploy. In light of these factors, we perceive a need for deployable materials that are easy to design, prototype, and deploy, and that can transform themselves in response to environmental stimuli, making them appropriate for ecological applications. In this paper, we present ExCell, a DIY-able system of water-responsive wooden linear actuators for self-actuating deployable structures. We show that ExCell can be used to develop a wide range of geometries, we present a prototyping method that can create accurate models of ExCell structures, and we suggest four possible applications for this system.

ExCell, short for Expanding Cellulose, is a water-activated wooden linear actuator that is simple to produce, simple to prototype with, and simple to understand.

Individual actuators are fabricated from laser-cut wood veneer that has been chemically processed and folded, and they feature tab-and-slot connectors that make it easy to assemble them into complex structures.

Process

ExCell actuators are produced using a similar process to E-Seed, but are designed to be manually folded, rather than formed around printed molds.

One of our goals was to create a resource for designers and researchers interested in making morphing wooden actuators. We outline a number of material, process, and design parameters that affect performance outcomes.

Applications

We present some demo applications that showcase the system’s use in environmental sensors, ecological interventions, as well as creative projects.