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Bacterial spore-based hygromorphs: A novel active material with potential for architectural applications

Lookup NU author(s): Emily Birch, Professor Ben BridgensORCiD, Professor Martyn Dade-Robertson



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© 2021 by the authors.This paper introduces a new active material which responds to changes in environmental humidity. There has been growing interest in active materials which are able to respond to their environment, creating dynamic architectural systems without the need for energy input or complex systems of sensors and actuators. A subset of these materials are hygromorphs, which respond to changes in relative humidity (RH) and wetting through shape change. Here, we introduce a novel hygromorphic material in the context of architectural design, composed of multiple monolayers of microbial spores of Bacillus subtilis and latex sheets. Methods of fabrication and testing for this new material are described, showing that small actuators made from this material demonstrate rapid, reversible and repeatable deflection in response to changes in RH. It is demonstrated that the hygromorphic actuators are able to lift at least 150% of their own mass. Investigations are also extended to understanding this new biomaterial in terms of meaningful work.

Publication metadata

Author(s): Birch E, Bridgens B, Zhang M, Dade-Robertson M

Publication type: Article

Publication status: Published

Journal: Sustainability

Year: 2021

Volume: 13

Issue: 7

Online publication date: 05/04/2021

Acceptance date: 17/03/2021

Date deposited: 27/04/2021

ISSN (electronic): 2071-1050

Publisher: MDPI AG


DOI: 10.3390/su13074030


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Funder referenceFunder name
Newcastle Universities Research Investment Fund