The insect cuticle: (5) Mild synthesis conditions

Very hot drink by Vase Petrovski via Flickr.com https://flic.kr/p/2UxA3Q

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This post is part of a series on the insect cuticle as a biological material that can inspire novel engineered materials. The characteristics of the cuticle, setting it apart from most synthetic/engineered materials, will be discussed in this series. The introduction to the series can be found here.

In Nature Easy Does It

Most biological materials, including the insect cuticle, are produced at ambient temperature and pressure. In addition, biological material synthesis often occurs in an aqueous environment. This is very different from how engineered materials are fabricated. Engineered materials are too commonly fabricated with the heat, beat and treat method.

Machine Meltdown by Darkday from Fickr.com

A lot of energy is added to the process of fabricating engineered materials. The material is usually forced to conform by adding pressure to it from the top down, and then (not always benign) chemicals are added to give the material additional properties. Nature teaches us that fabrication under mild synthesis conditions is possible too.

In general, most physiological processes related to growth in insects, including the fabrication of new cuticle, occur at temperatures between 40-100°F (5-40°C) and at standard atmosphere (~760 mmHg). This fabrication occurs from the ground up, no big machinery is needed, and only benign chemicals are used.

In my bioinspiration courses I ask students to create an Ashby plot (comparing tensile strength vs Young’s modulus) for engineered and biological materials.

Engineered materials plot.

Biological materials overlaying engineered materials plot. (By P. Karnstedt)

The activity reinforces that, at least for these two variables, biological materials are often as good, if not better, as engineered materials. Yet biological materials are fabricated at far milder synthesis conditions than engineered materials.


Some notes on how “extremophile insects” are able to survive, and maybe even grow, in extreme conditions.

Insects live in just about every habitat on Earth, from hot deserts and thermal springs to cold caves and frigid mountain streams. Clearly insects and other arthropods can survive some of the most inhospitable conditions on Earth. But some of extremophiles listed below will not molt under these extreme conditions.

Red Flat Bark Beetle by Tom Murray via BugGuide.

Cucujus clavipes larva by Lynette via Flickr.com

Belgica antarctica larvae by Richard Lee. Courtesy: National Science Foundation.

Himalayan jumping spider by Gavin Maxwell via Arkive

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