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

Emily Birch, Ben Bridgens, Meng Zhang, Martyn Dade-Robertson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)
109 Downloads (Pure)


This paper introduces a new active material which responds to changes in environmental humidity. There has been a 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 was demonstrated that the hygromorphic actuators are able to lift at least 150% of their own mass. Investigations were also extended to understanding this new biomaterial in terms of meaningful work.
Original languageEnglish
Article number4030
Number of pages19
Issue number7
Publication statusPublished - 5 Apr 2021


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