Bionics (also known as biomimicry, biological mimicry) is the application of biological methods and systems found in nature in the study and design of engineering systems and modern technology. In a narrower sense the term generally refers to the branch of biomedical engineering that applies cybernetics to the reproduction of functions of living organisms described by physiology, especially neurophysiology and electrophysiology, for example for the creation of artificial organs that are part of the nervous system or controlled by it.
The origins of this science can be traced to the studies of W. S. McCulloch and W. H. Pitts, presented in an article published in the Bulletin of Mathematics and Biophysics in 1943. These studies were aimed at creating models of neural networks that had the properties of the human nervous system and reproduce the behavior. The term bionic (probably originating from the Greek lemma “βίον” (pronounced “bion”), meaning “unit of life”, and the suffix -ic, meaning “like”, “similar to” or “in the manner of”, hence “like life”. Several dictionaries, however, also explain that the word is formed from the terms “biology” and “electronics”), in the meaning of biological models reproduced electronically, was introduced in 1958 by the American J. Steele. Bionics can be seen as a part of cybernetics: in fact, while cybernetics deals with the study and the more general realization of artificial systems, bionics tries to improve them or to create new ones, inspired by existing natural systems.
It is an interdisciplinary science that applies biological, physical and mathematical theories and techniques based on two fundamental operational considerations:
- that an artificial machine can perform tasks in a manner similar to a biological system;
- that the advantages of a biological system depend on the accumulation and reuse of data, the correlation of numerous data from numerous sensors, and the transfer processes used.
These two foundations provide the inspiration for drawing typical guidelines for bionics research that can be summarized as follows:
- biology performs the first phase with its work of observation, study, and analysis of living things resulting in the drafting of a working model;
- mathematics formalizes a model from the functional scheme;
- physics or engineering synthesize the above in order to build a model reproducing the function of interest.
We define “homological copy” the bionic system in which is artificially reproduced the exact biological functional scheme, while we define “simulated model” the bionic system in which are synthesized the functional parameters of the biological model in order to reproduce the same functionality of this without exactly reproducing its scheme. In complex systems it could be possible to observe a combination of the two techniques.
Scientific branches closely related to bionics are cybernetics (since biological systems are strongly retroactive and the study of retroactivity is particularly important in cybernetics), information theory (since, as already said in B is developed the study of data transfer) and, more generally, computer science which on the one hand could borrow concepts developed in bionics and on the other helps, through the use of simulators, allowing the refinement of models before the production of prototypes.
Two typical examples of studies inherent in this science are the study of the nervous system and the study of sensory organs. One of the most fascinating topics addressed is that of such an understanding of the human brain as to suggest ways of constructing mechanisms having some of its properties. The starting point of these studies has been the investigation of a fundamental component of the brain, the neuron, and of the way in which perturbations propagate between one neuron and another. An important result to which these researches have led was the creation by H. D. Crane in 1960 of a device, which he called neuristore, able to simulate the behavior of a neuron.
Bionics directs its research towards the understanding of the principles by which a neuronal network is able, evolving, to adapt, that is to perform operations initially impossible for it, or to repair some damage resulting from the destruction of its elements and the study of sensory organs, especially hearing and sight, in various animals and humans. From this study valuable ideas can be drawn for the realization of similar artificial systems that have the same functions.
Various types of sensory organs or receptors can be observed in nature, each of which is adapted to a particular purpose: receptors of mechanical, optical, chemical, thermal, and electrical sensations or, as they are commonly called, mechanoreceptors, photoreceptors, chemioreceptors, thermoreceptors, and electroreceptors (receptor). One of the earliest examples of research in this direction was the study of the method used by bats to reveal obstacles they encounter during their night flight.
The principle on which these animals are based is to make the ultrasonic waves, emitted by them, reflect on the obstacles in the flight path. This is the same principle on the basis of which it was possible to realize the detectors (sonar) used in submarines and similar detectors (radar) that make use of electromagnetic waves. The study of the bottle-nosed dolphin proved to be very interesting for the purpose of designing a sonar capable of detecting obstacles, both near and far, through the emission of a single acoustic signal.
Currently, however, a low-frequency, high-power sonar is needed to detect distant obstacles and a high-frequency sonar for nearby obstacles. Often the study of a particular sensory organ can lead to the design and fabrication of an artificial organ that retains its unique characteristics. The Soviets, for example, taking inspiration from the way in which some animals can receive low-frequency signals (from 1 Hz to a few tens of Hz), have built an artificial ear, through which it is possible to predict about 15 hours in advance the arrival of a storm. The realization of a synthetic nose that can distinguish between different substances is, however, much more difficult: the study of natural chemioreceptors could provide a significant boost to the realization of such an organ.
An interesting device, which simulates the behavior of the frog’s eye, has been realized in the laboratories of the RCA. The essential characteristic of the frog’s eye is that it cannot distinguish its prey unless they are moving. The electronic eye built according to this model could provide a useful tool in research concerning shape recognition. In addition, such a device is the first step towards the realization of a device for vehicle surveillance, recognition and guidance.
Other examples of studies addressed by bionics are the study of propulsion systems of some animals, particularly birds and fish, and the study of the effector organs, ie organs that execute the orders given by the brain. In the first case, the study of the motion of dolphins has allowed to ascertain that the remarkable speed that they can reach depends on the fact that their skin is made up of two layers that allow to absorb the effects of water turbulence during the movement. This principle has been applied to the realization of particular torpedoes that reach much higher speeds than ordinary torpedoes.
The study and imitation of the mechanisms by which the brain can give orders to the organs is of great use for the design and construction of equipment that can replace man in certain tasks and artificial limbs useful to physically impaired people. The attempts to formalize, through models, living organisms have led to the creation of mathematical theories, among which we can include the theory of automata (cybernetics), the theory of shape recognition, the theory of learning machines (perceptron). However, the most ambitious goal of this science is to build systems that have the peculiar characteristics of a living organism, namely: the ability to use information acquired from the surrounding environment to learn new forms of behavior; the ability to react to a wide variety of external situations and to decide how to behave to achieve a particular purpose.