Bionic (adj.) -- "describing a manufactured device or engineered tissue that  substitutes for, or augments, the function of a natural limb, organ or other portion of a biological body." 

The Five-Function Bionic Classification System (FFBCS) classifies a bionic device or tissue into four levels (0 = no function, 1 = below normal biologic function, 2 = equal to normal biologic function, or 3 = above normal biologic function) for each of five functional categories: Structure, Movement, Information, Power, and Growth. 

For example, a "S2/M2/I2/P1/G0" bionic device provides: equal to normal biological functionality for body structure, movement, and information transfer; less than normal biological function for power source and distribution; and no ability for growth or self-repair. 

THE FIVE FUNCTIONAL CATEGORIES

Further description of the five functional categories is as follows:

1) Structure: Structural functionality concerns macro-scale physical support within the body and the range of potential interaction of the body with the environment. It often corresponds to the function of the skeletal system.  Normal function involves structural strength, versatility, and potential motion equal to that of normal biological function. 

2) Movement: Movement functionality concerns macro-scale directed motion of bionic or natural body structures and the realization of potential interaction of the body with the environment.  It often corresponds to the function of the muscular system.  Normal function involves movement versatility, range and power equal to that of normal biological function.

3) Information: Information functionality concerns the transmission and processing of information between and within bionic and natural components of the body.  It often corresponds to the function of the nervous system.  Normal function involves transmission (and processing where appropriate) of commands from the brain to all portions of the body and transmission (and processing where appropriate) of sensory information from portions of the body to the brain.

4) Power: Power functionality concerns the creation or transferal, distribution, and use of power either entirely within the bionic component or between the body and the bionic component.  It generally corresponds to the gastro-intestinal, respiratory, circulatory, and intra-cellular biochemical systems of the body.  Normal function involves power systems for the bionic component that are equal in ease and strength of power creation and duration to that of a natural system through either an entirely man-made power system or an interface with the biological power system of the body.

5) Growth: Growth functionality concerns the ability of a bionic device or engineered tissue to grow or self-repair as needed to achieve or maintain full functionality.  It generally corresponds to cellular growth and repair processes.

APPLICATION OF THE CLASSIFICATION SYSTEM

Let us now consider application of the Five-Function Bionic Classification System (FFBCS) to a bionic human arm/hand.  Specifically, let us suppose that the arm/hand: provides skeletal strength equal to that of a human arm/hand; some, but not all, of the range of motion of a human arm/hand; some ability to transmit messages from the brain to the arm/hand for movement, but not as complete as that of a natural arm/hand; power (such as from a battery which must be recharged) that is not connected to as biological power within the body; and no ability to grow or self-repair.  This bionic arm/hand would be classified S2/M1/I1/P1/G0.

As a second application, we consider a bionic eye that that converts light into neural impulses and thus restores sight (but to a limited extent), is capable of normal eye movement as directed by the brain, and is powered by the biochemical processes that power biological cells.  Such a bionic eye would be classified as S0/M2/I1/P2/G0. 

Let us now consider a completely hypothetical application -- a chip with a neural-silicon interface that allows enhancement of human information processing or storage.  Let us further assume that it is powered by a battery that must be recharged.   Such a device would be classified S0/M0/I3/P1/G0.

LINKS TO SOME STATE-OF-THE-ART BIONIC TECHNOLOGIES

Bionic Sight:

Optobionics.com "Optobionics’ Artificial Silicon Retina™ microchip is designed to stimulate damaged retinal cells, allowing them to send visual signals again to the brain."

Visioncareinc.net "VisionCare Ophthalmic Technologies (VisionCare) is a privately-held development stage company engaged in the research, development, manufacture, and marketing of proprietary implantable ophthalmic devices and technologies that are intended to significantly improve vision and quality of life for individuals with untreatable retinal disorders."

John A. Moran Eye Center, University of Utah "Overview of human engineered and biological approaches to sight restoration"

Dobelle Institute "The Dobelle Institute (Portugal) Lda. and its predecessors has focused its efforts on Artificial Vision for the Blind and reported the successful attainment of that goal."

Neural Electrodes:

Bionic Technologies "Bionic Technologies, LLC, develops and manufactures affordable tools and turn-key systems for neuroscience researchers. These are based on high-density penetrating multielectrode arrays for the study of the parallel neural activity of the central and peripheral nervous system."

Bionic Arm/Hand:

Utah Arm and Hand System  "Since 1981, the Utah Arm has been the premier artificial myoelectric arm for above elbow amputees. It was originally developed at the University of Utah by the Center for Engineering Design, led by Dr. Steven Jacobsen."

Dextra Artificial Hand "Dextra artificial hand is the first to let a person use existing nerve pathways to control individual computer-driven mechanical fingers."

Prodigit Prosthetic Digit System "British scientists claim to have created the world's first truly bionic hand small enough to be used by a toddler.  The user sends a signal to move a muscle in the forearm, and electrodes detect this and pass the message on to the motors."

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