Bacterial Spore-Based Hygromorphs: A Novel Active Material with Potential for Architectural Applications

Round 1

Reviewer 1 Report

The paper presents in depth study of new bio-based actuator systems. Overall the paper is very well structured and clearly denotes the contribution of the research. The mechanical study and the cracking tests present very important observations.

This review presents minor changes suggested for improving the overall paper. 

1) My central comment lies with the reference to the two papers: Wang and Chen. Here, similar work is undertaken (is Chen the author here?) and it is not clearly denoted what the differences between the studies are. In the introdcution the present study implies that the application area of Architecture is novel and that Wang's paper on this subject is minor. However, the present paper does not truely engage architectural questions of programme or use. This is not in itself a problem as the paper has a clear   contribution in terms of methodology. But it would very much support the paper to clearly express what part of this method is similar to/different from the Wang study. This would also support the text further down in the document (section 3.5) in which Wang’s method is referenced.

2) The topic of architectural application should be clearer in the paper or simply cut out. Where the introduction has a convincing contextualization of the use of passive actuation in architecture – then this is not picked up on in neither the study nor the conclusion. A better arguments for scaling up (as done in later sections) and why this would be imporntat (application) could drive this architecture argument.

3) The suggestion of origami-like structures is not clearly followed through to the conclusion. it would be good to tie the introduction and the conclusion together by reflecting on this point. Here, reference to the field of actuated (4d) meta materials could give the paper a stronger breadth expanding beyond architectural questions of application.

4) In same section on hygromorphic actuated materials the contribution on actuation of spun fibres in knitted textiles by Jane Scott (Leeds) could be helpful. Also, Hensel’s work on same principles could support the references to Menges.

5) Figure 1, 2 present well established principles. In my view this is not important to include in the paper.

6) Fig 3 presents other author’s work on cladding panels. Again, this is not relevant to the apper in my view.

7) In section 3, three different baceteria types are explored. Here a diagramme expressing the different results could support communication of findings.

8) in end section 3.3 I am confused about the source of the reference. Are these studies part of the project (the pilot project on a nano-engine). I assume that this is referenced work (I believe this is MIT?) and in this case a clearer positioning of this as a state of the art section would support the paper.  

9) The quite limited testing (18 tests in all) seem very reduced. An argument for the scale of testing could support this.

 

 

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The authors presented a bilayered spore-based composite structure exhibiting deflection in response to humidity changes. The spore-based actuators are well characterized and the authors also showed an enhanced deflection by using multiple spore layers.  However, several questions have to be addressed.

1. The actuation of the hybrid bilayers were repeated only 6 times. How stable is the structure after tens or hundreds deflection? The data, i.e. the defelection values, can be shown in the results part. Is there any detachment of the spores or delamination of the bilayer structure?

2. The structure of the spore is not clear in Figure 4 as the solid lines lack detailed information. Please also change the font size in Figure 12.

3. Can the authors give some comments regarding the stability of the dormant spores? Is there any germination observed in a humidified environment during the long-termed test?

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Which is the relation between architectural design and building material behavior.

Key words not reflect your study area, for example the architectural design in which is a big area

In introduction section the authors wrote “In this paper we present a novel responsive” in academic paper you cannot use the “I, we “the research must be neutral. And in the same section you wrote” architectural applications” what you mean??

The article make confusion between architectural research area and the biological aspects and maybe organic materials behavior. In which make a big confusion for readers.

 

Author Response

This reviewer has been labeled unsuitable by the guest editor, so we will reserve our opinion on this reviewer report.