BACKGROUND

This is a consolidation of the three papers published in the Springer-Open journal, “The Journal of Robotics and Biomimetics” in a special issue on nano-/micro-robotics under the following titles:

1. A biomimetic study of natural attachment mechanisms— Arctium minus Part 1 [1]

2. A biomimetic study of natural attachment mechanisms: imaging cellulose and chitin Part 2 [2]

3. Micro-design using frictional, hooked, attachment mechanisms: a biomimetic study of natural attachment mechanisms—Part 3 [3]

Frankly the engineer in the researcher took a biology Ph.D. and under the auspices of researching attachment mechanisms, he researched micro-design. This is not least because the only method available to him for shape acquisition at that time to assess mechanical properties was 2-D digitising which his own work for his Master’s thesis in mechanical engineering had suggested was inadequate for that time (2001/2).

The title of part 3 above displays the underlying hypothesis behind the exploration of the detail of papers 1 and 2. It accepts the viability of using cladistic methods to arrive at a scenario where a structure that has survived the “evolutionary sieve” is selected, to quote Nicklaus et al [4], over the use of Linnaeus or other classification methods which can be seen as insignificantly better when it comes to evolutionary manifestations of properties and/or structures. In other words all evolutionary models are all imperfect and so it is that the solution must indeed be imperfect too if it is to reflect the true nature of the Natural World i.e. testing is necessary before any firm conclusions can be reached. The use of the hook is a not very interesting thing, relatively. But it is also the ideal way to start with the designing of micro-sized (~100micron) objects because of the over-hangs of the hooks, which are of the minimal complexities to test the programmer and they can be assembled into machine-like components for manufacture. Their origins are a little too old for one to understand their development since the designs are based in evolutionary theory, which is utilised in order to identify which structures are viable and of suitable length and strength to be of use in the manufacture of computer components to attach to PCB’s (printed circuit boards).

THE THESIS PROPOSAL

This work derives from a thesis proposal: “The Functional Ecology and Mechanical Properties of Biological Hooks in Nature”. This is another way of requesting the classification of the set of all hooks according to their shape/structure and mechanical properties and here a simple method of assessing a structure is utilised and that is by naked eye, from the outside with no internal examination. This would correspond to the earliest form of Naturalism prsumably, classifying flora and fauna according to their appearance and function. Dissatisfaction with the current methods of shape acquisition and manufacture led to the research path which was followed.

It led to the theory that there is a way of being able to measure the proportional forces being used in the attachment of those mechanisms that could be measured and used to manufacture a hook that would indeed be of use, but not as expected. i.e. A hook shape need not be used only, if at all, for mechanical interlock. It is those hidden secrets that are sought, hidden from the human eye but not from the measuring instruments.

Current technology in 2002/3, where the latest paper on shape acquisition detailed the profile of a tiger’s claw [5] using 2-D digitising, was inadequate. Now through the work of Hirt et al [6], by their work on SEM (scanning electrodeposition electron microscopy) it is possible to move forward. Now a hook can be manufactured at a 1:1 scale to the fluorescent and translucent biological specimen that is to be reverse engineered and that means that designers are on the brink of being able to make things that are of use, in the micro-realm (of the order of 10-100 microns in size). It all began with the discovery that it was possible to image one of the hooked probabilistic fasteners under laser light, namely the cellulose hook of burdock (Arctium minus). Therefore the work continued with the chitinous growths of the bee and the grasshopper (Apis mellifera and Omocestus viridulus) tarsi [2]. This encounter with luck was able to make true the theory that the use of the single phase confocal microscope could be for the imaging of a specimen and then the transfer of data directly to a layered manufacture device that was suitable, namely the SEM work of Hirt et al [6]. The point of this imaging was to use it to describe each member of the class of probabilistic fasteners as a number, namely one for the hook, two for the attachment mechanism of the grasshopper O. viridulus with two hooks, and three for the double set of hooks, namely A. mellifera with a separating arolium which could make it all seem like they are intended to prove the theory right and not wrong. The chance of being on top of a specimen structure available without travelling is immense, as these were all available at the University of Bath which is set in the countryside of Western England. Particularly the burdock which was used as the basis of Velcro but it is concluded this is not the limit and it seemed better to use it than to use the others (see below), as it will be shown, for the production of a new hook, a multi-use flat structure of multiple hooks that could be used without being entirely known, as per its value and knowledge. i.e. if it is to be the one to be imitated then it needs to be studied more now so that it can be manufactured.

INSERT FIGURE 1 AND CAPTION

Referring to the Figure of the A. minus (burdock) “head” or seedpod, which along with the other four hook specimens studied by Gorb, namely the Agrimonia eupatoria, Circaea lutetiana, Galium aparine, and Geum urbanum” [7], all form probabilistic fasteners which is an important classification.

AIM

The aim is to develop a Universal micro-robotic frictional probablistic attachment mechanism with a performance that can be modelled graphically, using Biomimetic principles. This is called a Universal Foot after the fact that a human foot is a frictional probabilistic attachment mechanism and because its performance is to be modelled graphically for design, performance, material, quality and other parameters, its universal qualities. Cladistic methods are used for selection of a long-shafted, probabilistic, frictional, cellulose hook as a basis for the design.

METHOD

The above question is asked because the burdock hook is stronger and not weaker and therefore the best example to be reproduced and hence it is of the best form, whether of cellulose or of chitin, since it has a long shaft and an end that is available to the head of a layered manufacturing device. In the end it is a misnomer to think that it could be any more than a reproduction of the shaft that makes it fast and not slow to reproduce since it is of a cellulose hook, not chitin which is a very complicated biomaterial and therefore it is not easy to reproduce its properties. With cellulose however, it is a known material that has been much studied and therefore it is available to be reproduced via a green theory workplace in the future. Until then we shall make do with copper, not gold, since it is the cheaper of the two and therefore available to mass production and can be seen to be the best fit for the solution of making a reproduce-able hook that will sustain in making it to the end of the product lifecycle. See [6]. Figure 2 below shows the single-phase confocal microscope image sections that are utilised by SEM. Each .tiff file is used to construct a 3 dimensional image or the cubic voxels are directly utilised by the layered manufacturing device.

[INSERT FIGURE 2 AND CAPTION]

With respect to a Universal Foot it is impossible to sustain its probability of fastening since there is a possibility that it should not hold the correct angle on the surface/substrate. That will be overcome with a hinge that will allow the foot to align with the ground according to its angle and not the angle of application. It will be seen that there are a number of solutions to the problem of a Universal Foot and that means a testrig will have to be devised such that it can measure the forces with which a hook attaches to a substrate and that is the way through to the end of the series such that each member of the group of probabilistic fasteners can be measured, of different biological materials as imaged in [2]. In the meantime it is possible to make deductions such that a design can be arrived at that resembles a caterpillar yet makes use of the hook of the burdock and the range of movement that requires needful thinking so that it can be measured. Once this is done we have a product which can be commercialised. Part 2 [2] contains the results of the experimentation to image cellulose and chitin and this will prove useful in the future when a wide range of hooking and other mechanisms/devices are considered since it will be in the interest of those continuing the study to know the difference between the two and whether they can use the data to make hooks that are biological such as those to attach to the stomach wall or the vessels of the heart since they bear cilia which makes them difficult to render in a stainless steel as with a stent. But when it is available it may be possible to make them from a biological material which does not dissolve such as the Massachusetts Institute of Technology device which, when swallowed, removes a watch battery from the stomach wall to avoid a ulcer forming there or to patch a wound, steered by magnetic fields and which is still in the experimental phase. It is made from pig’s sinew which is insoluble but which does not lend itself to electro-deposition so an alternative biomaterial will need to be found. The electrodeposition of stainless steel has been investigated by Hasegawa et al [8] and it appears to allow for copper to be plated in stainless steel, enabling a biologically inert structure to be manufactured.

RESULTS

 

[INSERT FIGURE 3 AND CAPTION]

 

The result of this research is a hypothesis that has proved at least partly successful thus far. Please bear in mind that a design is being presented for a structure too small for human eye-sight to assess effectively. Within the constraints of Nachtigal’s classifications [9], three hooked classes have been imaged on a confocal microscope [2] and all that remains is to pass the data to the SEM of [6] to produce prototypes for testing. In a manner of regard, essentially multiple Class 1 hooks have been assembled in an array as a collective or field. They are shaped as per the cellulose form of the burdock hook which is simple and shows no stress modifications, with a tapered tip. Manufactured from copper, their attributes have yet to be discovered but it is hoped that it will yield an attachment device that will succeed in vertical assent via quadrupedal locomotion. It is designed to be multi-use, temporary and permanent, probabilistic and frictional as its mechanical properties. Its physical properties will of course differ not least for copper’s well-known capacitance to pass electric current and its magnetic properties.

[INSERT FIGURE 4 AND CAPTION]

DISCUSSION

For many years scientists have been studying the work done and methods of doing so in the animal world. The work being energy transfer and the methods, from walking to holding a stone as a hammer. It now has become possible to study the intimate details of the assembly of life and it is also becoming a useful aptitude to be able to make the correct decision with regards to design and this encompasses the system as well as the part itself which is being considered. So it becomes a necessary point to make that one can now physically reproduce to microns in accuracy and no longer is it necessary to stick to statistical methods of assessment and aspiration. Physical biology can now be measured at a micron level as can the performance of these structures, albeit in metal. These metal structures have yet to be tested but their material composition shall add to their value it is believed.

At a foundation has been a determined effort to move towards direct data transfer, from microscope image to layered manufacture, as it is called now. Because scaling effects exist, the mechanical properties of the vast majority of hooked attachment mechanisms can only be mimicked when manufactured at the same order of size.

 

[INSERT TABLE 1]

 

Table 1: Originating structures of long shafted hooks available in the literature. [1] and [7].

CONCLUSION

The door is creaking open, upon the region of science and manufacturing technology called Microdesign. As never before the opportunity arises for manufacturing expansion into the realm of micron-sized structural designs that could benefit man through their use of their size. In the light of new developments into Biomedical structures there is a need for stable materials at this scale to be used within biological systems. SEM has been proved accurate with both copper and gold so both are options to work with so far.

The hook, as a shape of low-complexity, proved an excellent example to demonstrate the limits of current technology and its new abilities due to the work of Hirt et al. In terms of 3-D date collection via laser scanning, resolution of an overhang is impossible in C++ programming terms unless one moves the head of the layered manufacturing device as per [6] in which case acute angles can be reproduced. Surface modelling via Canny Edge Detection methods does not provide for holes or overhangs in the first instance.

The set of all Biological hooks in Nature can be divided along lines of material, structure and function. When considering shape and form one must consider it surprising that all biomaterial seem able to form hook shapes and do. At the smallest scale, near atomic level and in the region where self-assembly occurs, there must be incentive to form these shapes which is a directed response to the environment. It could be that these early shapes, these hooks, were in fact invented by Life itself as a form of camouflage with dual purpose and thereby were able to be used to vary Life without threatening it. For the first, the very first curve or hook shapes on earth must have occurred in the rock material of the surface and other parts.

A crude mapping system is available to us at any time, much like a parts manufacturer would catalogue a system of related parts. But this is not the purpose of the research, which is into micro-design of which the hook-shape forms a complex challenge.

 

 

 

 

 

 

 

Figure 4 [10] shows a design space for fasteners, without microfasteners included except in the form of gecko-feet and a macro-sized form of velcro. There must be a place for these new microfasteners that are being suggested, microdesigned after Natural attachments that rise into the empty space of high relative strength and high-reusability on the chart.

 

REFERENCES

1. Saunders B E. Biomimetic study of natural attachment mechanisms-imaging cellulose and chitin part 2. J. Robot. Biomim. 2015;2:7. doi:10.1186/s40638-015-0032-9.

2. Saunders B E. A biomimetic study of natural attachment mechanisms – Arctium minus part 1. J. Robot. Biomim. 2015:2:4. DOI10.1186/s40638-015-0028-5

3. Saunders B E Microdesign using frictional, hooked, attachment mechanisms: a biomimetic study of natural attachment mechanisms – part 3. J. Robot. Biomim. 2016:3:4. DOI10.1186/s40638-016-0040-4

4. Mattheuk C and Reuss S The Claw of the Tiger: An Assessment of its Mechanical Shape Optimization, J. theor. Biol. (1991) 150, 323-328

5. Nicklaus, K. J. Plant, (1992) Biomechanics – An engineering approach to plant form and function (Chapter 10), Biomechanics and Plant Evolution, University of Chicago Press, pp. 474–530

6. Hirt L, Ihle S, Pan Z, Dorwling-Carter L, Reiser A, Wheeler JM, Spolenak R, Vörös J, Zambelli T. Template-free 3D microprinting of metals using a force-controlled nanopipette for layer-by-layer electrodeposition. Adv Mater. 2016;. DOI:10.1002/adma.201504967.

7. Gorb E, Gorb SN Contact separation force of the fruit burrs in four plant species adapted to dispersal by mechanical interlocking. Plant Physiol Biochem. 2002;40:373–81

8. Hasegawa M, Yoon S, b Guillonneau G, Zhan Y, Frantz C, Niederberger C, Weidenkaff A, Michlerad J, Philippead L The electrodeposition of FeCrNi stainless steel: microstructural changes induced by anode reactions Phys. Chem. Chem. Phys., 2014,16, 26375-26384 DOI: 10.1039/C4CP03744H

9. “Biological Mechanisms of Attachment, The Comparative Morphology and Bioengineering of Organs for Linkage, Suction and Adhesion”, W Nachtigall, 1974 translated by M A Biederman-Thorson, Springer-Verlag, ISBN 3-540-06550-4

10. “Systematic Technology Transfer from Biology to Engineering” J F V Vincent and D L Mann, Phil. Trans. R Soc. Lond. A(2002) 360, pp 159-173

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