“I have a specific problem to solve; let me see if nature gives some ideas.”
Dr Lakhtakia and an international team of researchers from USA, Italy and Spain were looking for a better strategy to channel sunlight into solar cells in small-scale installations. They believed that apart from harvesting direct sunlight, the cells should also recycle energy emitted by other lighting sources such as LED lamps. This requires solar cells that can harvest energy from diffused light. That is, we require solar cells with a large angular field of view to maximise the capture of incident light regardless of its direction.
Recently, the team consciously decided to look for solutions in nature. That is when they observed how difficult it was to catch houseflies.
“Houseflies have big eyes and can see 270 degrees around them. Certainly, this wide angular field of view arises from the positions of the two eyes; humans too would have a much wider angular field of view than what they have (170 degrees) if their eyes were located on their temples. But, the team reasoned that the wide angular field of view could also arise from the compound eyes of the housefly Musca domestica,” says Dr Lakhtakia.
Other insects such as the blowfly and the horsefly also have compound eyes. Basically, in these insects, each eye is made up of innumerable micro-sized cylindrical eyelets arrayed on a curved surface. Light propagating along the axis of an eyelet is collected to form an image, but light propagating in other directions and reaching an eyelet is absorbed by its dark side wall. Although the spatial resolution of the overall image formed in the brain by the fusion of the individual images is quite low, the field of view is very large.
Two years ago, the team started a two-phase research program to adapt the scalloped and curved outer surface of a compound eye to texture the exposed face of a solar-cell device. They report good progress in both phases. Although this success is a measure of the scientists’ sweat and blood, they also have nature to thank, at least for that timely spark.
In another interesting example, the engineers of Energid Robotics and Machine Vision set out to develop a humanoid robot that can work like a human arm. The company’s director and country manager, Jayakrishnan T., says, “Our unique robot manipulator series, the Cyton humanoid manipulators mimic nature’s ultimate engineering marvel—the human! We copied the configuration of the human arm to do the kinematics design of that robot. These robots have the properties of redundancy and bifurcation, which enable placement of multiple hands or tools at desired positions and orientations within the robot’s workspace in an unlimited number of ways. This was our main focus while we tried to design the robot following the human arm geometry. These humanoid arms can perform any manipulation task that a human being can do with his arm with a limited payload capacity of up to one kilogram.” Cyton was completely designed and developed in India.
In general, robotics offers many examples of the nature-inspired kind. Energid itself has another example to offer: their Citrus fruit harvester works much like how a frog hunts a bee.
“I was trying for long to solve a problem. Luckily, nature gave me a clue.”
In the previous approach, the engineers decided consciously to study nature in order to find a solution to their problem. The experience of Dr Vinay Vaidya, chief technology officer, Engineering, and CREST Leader, KPIT Cummins Infosystems, is slightly different. Dr Vaidya was on the task of developing an image enhancement system for automobile, when he chanced upon a clue from nature in the form of the shape of the leaf. He was vigilant enough to notice it, research it further and use it to advance his technology.
Dr Vaidya recounts, “While we were working on finding a solution to enhance an image, especially under night driving conditions, I came across a leaf with a shape similar to that of cardioids.”
A cardioid has remarkable properties. The shape is formed in an interesting way. Take two circles of unit radius, rotate one circle over the circumference of another and the trajectory that is formed takes the shape of a cardioid.
[stextbox id=”info”]Strongest playgrounds
Some areas of science and technology where biomimetic techniques have been found to be very effective are:
1. Machine vision systems
2. Machine hearing systems
3. Signal amplifiers
4. Navigational systems
5. Data converters
6. Neural networks
7. Nanorobot antibodies (to seek and destroy disease-causing bacteria)
8. Artificial organs, arms, legs, hands and feet
9. Implantable devices[/stextbox]
Dr Vaidya continues, “Our image enhancement solution is solely inspired by the shape of the leaf, which helped us to enhance the image. We could device a function around cardioids: if there are pixels which are very dark, then increase the pixel value; and reduce the value if there are brighter pixels. Through the entire exercise we actually came up with a solution for better images under night driving conditions. We have filed for a patent that includes cardioid method along with other novelties for night vision,” he says.
Inspiration or imitation?
Nature-inspired technologies fall into a certain classification, or rather progression, of terminologies such as bio-inspired, biomimetic, biomorphic and bio-replication.
Bio-inspired. Any artificial design, process or product that is inspired by nature is a bio-inspired one. Some researchers say that it is an umbrella term that covers all the others, while some restrict it to just those products which exhibit a natural functionality but do not employ the underlying natural principles.
Bio-morphic. “Bio-inspired just takes inspiration from biology, whereas bio-morphic seeks to exploit the same solutions or employ the same organising principles. The term ‘morphic’ comes from structure, emphasising arriving at the same function by mimicking the underlying structure or architecture,” explains Dr Kwabena Boahen, associate professor, Bioengineering Department, Stanford University.
Dr Boahen is principal investigator of their Brain in Silicon project—a biomorphic or rather neuromorphic one. The team tries to use existing knowledge of the brain’s functioning to design an affordable supercomputer. The other complementary side of their research is to use the same supercomputer to further investigate the functioning of the brain.
According to the team, “We model brains using an approach far more efficient than software simulation: We emulate the flow of ions directly with the flow of electrons—don’t worry, on the outside it looks just like software.”
Developed through a neuromorphic approach, this supercomputer, called the Neurogrid, has a parallel, interconnected architecture like the brain. Its building block is not a logic gate—like in a digital computer—but a silicon neuron whose behaviour and connectivity are programmable. Read more about the programmable silicon neuron at http://www.stanford. edu/group/brainsinsilicon/about. html#Emulate.
Bio-replication. Some also use the term ‘bio-replication’ interchangeably with ‘bio-morphic.’ However, there is believed to be a subtle distinction. Bio-morphic mimics the underlying structure, whereas bio-replication completely reproduces it. The only difference between the natural and artificial designs in the case of replication is brought about by the difference in material.
Biomimetics. As a middle path, we have biomimetics, which involves mimicking a natural function with certain features of the natural structure that make the function possible reproduced in the design.
“Biomimetics utilises natural techniques for inspiration, and not the absolute blueprints. The needs of any individual organism are likely to be vastly different from our own, and most adaptations are reached through compromises. A given eye design may have good anti-reflection properties, but they may have been tuned specifically for a small cone of vision, or be restricted in the wavelengths of operation,” comments Dr Judith Braganca, BITS Pilani, KK Birla Campus, Goa.
“Biomimetics provides an immense database of designs that can inspire creative thought. This technique evolves and grows with the development in research and technology much like the evolution of nature,” he adds.
Dr Braganca works with a group of salt-loving micro-organisms that are known to inhabit salt pans. These grow under stress conditions of high solar radiation, 25 per cent salt and sometimes anoxic (anaerobic) conditions. They are brightly-pigmented with red, orange and pink pigments.
“These pigments have been implicated to protect the organisms from sunlight as their production can be increased with exposure to light. So, we are in the process of designing a sunscreen with these haloarchaeal pigments for human use so it will protect the skin from ultraviolet (UV) radiation,” she explains.
Why let nature solve our problems?
The strongest reasons cited in favour of nature-inspired solutions are that they are likely to be evolutionary and sustainable. “Biology is really the only technology that we know is sustainable. The more we understand and exploit biological solutions, the more sustainable our technology will become. In the neuro realm, this means lower power, higher robustness, and the ability to scale to the nano-scale, despite increasing heterogeneity and randomness,” says Dr Boahen.
Jayakrishnan opines that solutions based on nature are also very robust and adaptive. He says, “With over two billion years of research and development, nature has evolved highly-efficient materials, structures, tools, mechanisms, processes, algorithms, methods and systems. Design approaches inspired by nature often result in systems or processes that exhibit much greater robustness in performance in unstructured environments compared to existing ones.”
Dr Lakhtakia points out that there might be certain advantages in hindsight too. “Imitation of a natural solution could be beneficial as it may open up a possibility not thought of earlier. For instance, one could copy the shape of a certain natural structure for optical purposes but later find that the shape confers mechanical robustness as well under certain conditions. In pharmaceutical ethnobotany, a certain drug isolated from a certain plant used traditionally for the treatment of a particular ailment may turn out to be useful against another ailment as well. Thus, there may be an additional advantage, but only in hindsight,” he explains.
Respect and learn, do not underestimate
While it sounds all hunky-dory, nature-inspired theories, designs and products are not as easy as the simplified accounts of Newton’s or Archimedes’ discoveries that we read in primary school. It involves systematic research, a multi-disciplinary approach and lots of risk too.
In the course of the discussion, Jayakrishnan makes it clear that to gain inspiration and guidance from nature is not an easy task. It involves multidisciplinary research and a certain degree of reverse engineering too.
“The creations of nature are biological models subjected to principles of physics, chemistry, mechanical engineering, materials science and many other branches of science and engineering. So, it is required to perform a highly systematic reverse engineering by dividing the system or process based on each category of the principles involved, mathematically modelling and identifying an analogy for each from the artificial world,” he says.
Dr Braganca agrees, “Creating any nature-inspired design or product requires an amalgamation of many sciences. To replicate the photomechanical heat-sensing mechanism of the beetle Melanophila acuminate for creating a biomimetic infrared sensor, one would require expertise in both the biology and engineering,” she says.
So, in general, mapping the concepts learnt from nature to the physical realm is a huge challenge. Nature has many complex creatures that have various ways of structure, survival and signalling. Applying these to product and design applications involves manifold challenges, which are not to be underestimated while undertaking a biomimetic project. Of course, it is obvious that the benefits make the efforts worthwhile. So, wish these researchers all the best!
The author is a technically-qualified freelance writer, editor and hands-on mom based in Bengaluru