Ille C. Gebeshuber

Atomic force microscopy study of living diatoms in ambient conditions

We present the first in vivo study of diatoms using atomic force microscopy (AFM). Three chain‐forming, benthic freshwater species –Eunotia sudetica, Navicula seminulum and a yet unidentified species – are directly imaged while growing on glass slides. Using the AFM, we imaged the topography of the diatom frustules at the nanometre range scale and we determined the thickness of the organic case enveloping the siliceous skeleton of the cell (10 nm). Imaging proved to be stable for several hours, thereby offering the possibility to study long‐term dynamic changes, such as biomineralization or cell movement, as they occur. We also focused on the natural adhesives produced by these unicellular organisms to adhere to other cells or the substratum. Most man‐made adhesives fail in wet conditions, owing to chemical modification of the adhesive or its substrate. Diatoms produce adhesives that are extremely strong and robust both in fresh‐ and in seawater environments. Our phase‐imaging and force‐pulling experiments reveal the characteristics of these natural adhesives that might be of use in designing man‐made analogues that function in wet environments. Engineering stable underwater adhesives currently poses a major technical challenge.

A gaze into the crystal ball:biomimetics in the year 2059

Abstract Biomimetics is a field that has the potential to drive major technical advances. It might substantially support successful mastering of major global challenges. In the first part of the article, the current state of biomimetics is reviewed, and goals and visions of biomimetics are presented. Subsequently, possible biomimetic scenarios to overcome the major global challenges, as indicated by the Millennium Project, are envisaged. Those of the 15 challenges (sustainable development, water, population and resources, democratization, long-term perspectives, information technology, the rich—poor gap, health, capacity to decide, peace and conflict, status of women, transnational crime, energy, science and technology, and global ethics) where biomimetics might provide relevant contributions are considered in more detail. The year 2059 will mark the 100th anniversary of Part C of the Proceedings of the Institution of Mechanical Engineers, the Journal of Mechanical Engineering Science. By this time, some of these challenges will hopefully have been successfully dealt with, possibly with major contribution from biomimetics. A new Leitwissenschaft and a new type of ‘biological technology’ are emerging, and in biology more and more causation and natural laws are being uncovered. In order to estimate the fields of biology from which technical innovations are likely to appear, the amount of causal knowledge is estimated by comparing it with correlational knowledge in the respective fields. In some fields of biology, such as biochemistry and physiology, the amount of causal laws is high, whereas in fields such as developmental biology and ecology, we are just at the beginning. However, sometimes ideas and inspirations can also stem from nature when the causations are not known. The biomimetic approach might change the research landscape and the engineering culture dramatically, by the blending of disciplines (interdisciplinarity). The term ‘technoscience’ denotes the field where science and technology are inseparably interconnected, the trend goes from papers to patents, and the scientific ‘search for truth’ is increasingly replaced by search for applications with a potential economic value. Although the trend in many scientific fields goes towards applications for the market, a lot of disciplines will stick to the traditional picture of science. An open question left to the future is whether the one development or the other (technoscience or pure science) is an advantage for the future of humans. In the subsequent section, the article gives information about organizations active in biomimetics. It shows the relevance of biomimetics on a global scale, and gives reasons for promoting transdisciplinary learning. Increasing interdisciplinarity calls for novel ways to educate the young. Brian Cambournes ‘Conditions of Learning’ theory is recommended in this respect. This dynamic and evolving model for literacy learning comprises the concepts immersion, demonstration, engagement, expectations, responsibility, employment, approximation, and response. Each of these conditions supports both the student and the teacher in their discovery of learning, helps provide a context within which to learn, and creates an interactive and dynamic experience between the learner and the content. In the year 2059, researchers and developers who routinely think across boundaries shall successfully implement knowledge in solving the major challenges of their time!

Biotribology inspires new technologies

This review deals with natural biotribological systems and how they have inspired novel micro- and nanotechnological applications. The biogenic devices presented here have functional units in the micro- and nanometer regime and have been evolutionarily optimized over millions of years. The examples discussed comprise natural micromechanical systems made of nanostructured silica (diatoms produce hinges and interlocking devices on the micrometer scale and below), adhesive molecules (selectin and integrin) that can switch states and account for white blood cell rolling in endothelial cells, dry adhesives as they occur on the Gecko foot and certain insect attachment pads, and single molecules that serve as strong self-healing adhesives (diatom underwater adhesives, abalone shell proteins).

Bio-inspired polarized skylight-based navigation sensors: a review.

Animal senses cover a broad range of signal types and signal bandwidths and have inspired various sensors and bioinstrumentation devices for biological and medical applications. Insects, such as desert ants and honeybees, for example, utilize polarized skylight pattern-based information in their navigation activities. They reliably return to their nests and hives from places many kilometers away. The insect navigation system involves the dorsal rim area in their compound eyes and the corresponding polarization sensitive neurons in the brain. The dorsal rim area is equipped with photoreceptors, which have orthogonally arranged small hair-like structures termed microvilli. These are the specialized sensors for the detection of polarized skylight patterns (e-vector orientation). Various research groups have been working on the development of novel navigation systems inspired by polarized skylight-based navigation in animals. Their major contributions are critically reviewed. One focus of current research activities is on imitating the integration path mechanism in desert ants. The potential for simple, high performance miniaturized bioinstrumentation that can assist people in navigation will be explored.

Micromechanics in biogenic hydrated silica: Hinges and interlocking devices in diatoms

Abstract Diatoms are single-celled organisms with rigid parts in relative motion at the micrometre scale and below. These biogenic hydrated silica structures have elaborate shapes, interlocking devices, and, in some cases, hinged structures. The silica shells of the diatoms experience various forces from the environment and also from the cell itself when it grows and divides, and the form of these micromechanical parts has been evolutionarily optimized during the last 150 million years or more, achieving mechanical stability. Linking structures of several diatom species such as Aulacoseira, Corethron, and Ellerbeckia are presented in high-resolution SEM images and their structure and presumed functions are correlated. Currently, the industry for micro- and nanoelectromechanical devices (MEMS and NEMS) puts great effort into investigating tribology on the micro- and nanometre scale. It is suggested that micro- and nanotribologists meet with diatomists to discuss future common research attempts regarding biomimetic ideas and approaches for novel and/or improved MEMS and NEMS with optimized tribological properties.

Surface analysis on rolling bearings after exposure to defined electric stress

Abstract This article gives an overview about classical and frequency converter-induced spurious bearing currents in induction machines and discusses typical damage patterns caused by the current passage. To investigate on the electric damage mechanisms, test bearings are operated in a test rig and exposed to specific (classical low-frequency, and high-frequency) bearing currents. The induced damages to the surfaces are analysed visually and with the help of an atomic force microscope, and compared for the different electric regimes applied. Further, the electrically damaged bearing surfaces are characterized by standard roughness parameters. The surface structure observable on certain test bearings shows good correlation to the structure found with a bearing that had failed in the field under similar electric conditions. One of the investigated electric regimes applying high-frequency currents proved capable of generating fluting patterns - as found in real applications - on the test rig. The experiments also indicate that high-frequency bearing currents, although in total dissipating less energy, are more dangerous to a bearing than continuous current flow. The presented method gives a good starting point for further investigation on electric current damage in bearings, especially regarding high-frequency bearing currents, and on bearing/grease lifetime under specific electric regimes.

In vivo nanoscale atomic force microscopy investigation of diatom adhesion properties

Abstract Most state of the art adhesives fail to bond under wet conditions. Therefore, knowledge of the intrinsic properties of natural adhesives might give valuable information for future engineering approaches. This work investigates the adhesive that Eunotia sudetica, a species of benthic freshwater diatoms, produces to attach itself to a substrate. Atomic force spectroscopy under aqueous solution reveals the modular, self-healing properties of this natural adhesive.

Exploring the Innovational Potential of Biomimetics for Novel 3D MEMS

A novel way to describe the complexity of biological and engineering approaches depending on the number of different base materials is proposed: Either many materials are used (material dominates) or few materials (form dominates) or just one material (structure dominates). The complexity of the approach (in biology as well as in engineering) increases with decreasing number of base materials. Biomimetics, i.e., technology transfer from biology to engineering, is especially promising in MEMS development because of the material constraints in both fields. The Biomimicry Innovation Method is applied here for the first time to identify naturally nanostructured rigid functional materials, and subsequently analyse their prospect in terms of inspiring MEMS development.

An attempt to reveal synergies between biology and mechanical engineering

Biomimetics is a continuously growing field. In this article specific examples for successful technology transfer among biology and engineering are classified along a newly proposed scheme of the field — biomimetics by analogy and biomimetics by induction — complemented by technical biology. Famous examples as well as niche applications are presented: winglets on airplanes, an optimized straw-bale screw, Velcro, and self-cleaning surfaces and paints, as well as investigations on spiders. The need of a common language for biologists and engineers, in which descriptions at different level of detail are more compatible, is stressed and general principles that can be applied by engineers who are not at all involved in biology are presented.

Tribology in biology

Abstract Man has conducted research in the field of tribology for several thousands of years. Nature has been producing lubricants and adhesives for millions of years. Biotribologists gather information about biological surfaces in relative motion, their friction, adhesion, lubrication and wear, and apply this knowledge to technological innovation as well as to the development of environmentally sound products. Ongoing miniaturisation of technological devices such as hard disk drives and biosensors increases the necessity for the fundamental understanding of tribological phenomena at the micro- and nanometre scale. Biological systems excel also at this scale and might serve as templates for developing the next generation of tools based on nano- and microscale technologies. Examples of systems with optimised biotribological properties are: articular cartilage, a bioactive surface which has a friction coefficient of only 0·001; adaptive adhesion of white blood cells rolling along the layer of cells that lines blood vessels in response to inflammatory signals; and diatoms, micrometre sized glass making organisms that have rigid parts in relative motion. These and other systems have great potential to serve as model systems also for innovations in micro- and nanotechnology.