For many upper limb amputees, the ability to participate in activities of daily living necessitates using multiple prosthetic arms and/or terminal devices. For most amputees, this means using a combination of hands and hooks, cosmetic as well as functional prostheses. The appropriate terminal device gives the amputees freedom to be independent,to go back to their jobs after a traumatic injury, and carry out any other required activities.
With technological advancements, high-tech upper-limb prosthetic and bionic arms, and components are evolving constantly. For instance, a large number of companies are manufacturing multi-articulating terminal devices and prosthetic hands that are sophisticated and mimic the functions of the anatomical hand. These include, but are not limited to the Zeus Bionic Hand by Aether Biomedical; the Bebionic hand from Steeper (Ottobock); the i-limb from Touch Bionics (Ossur); TASKA Hand from Taska Prosthetics and the Michelangelo hand from Ottobock; all of which offer a variety of options,
ZEUS BIONIC HAND
The Zeus Bionic Hand is an EMG controlled, multi action terminal device consisting of individual finger stalling for easy capture and conformation to the objects’ shapes and sizes. It has the ability to provide 12 different types of grips along with 2 more customisable grips that are: precision open and closed grips, power grip, active index grip, tripod open and closed grips, key grip, hook grip, finger point, mouse grip, open palm and resting hand. The electrodes offering closed loop motor control, are of 6.7mm in height, one of the lowest, and therefore, they allow for constructing a socket that can be completely sealed. The sensors provide proportional control as they are aware about the finger positions and the applied forces. A major advantage of the Zeus hand is the single button interface of the charging port that lets the user check battery function easily by pressing and holding the button to power the device on or off, or press it once to show battery level. Since the battery is only 5mm tall, the charging port can be fabricated into a socket with little inward protrusion, allowing for more versatility in battery and controller placement.
i-LIMB
The iLimb (Ultra and Quantum) are myoelectric hands with multi articulating fingers, that provide 5 degrees of freedom with different grips. iLimb Ultra has 18 grip options with a thumb that can be rotated electronically. It is intended for low to moderate levels of impact and can be prescribed for amputees with wrist disarticulations, transradial and transhumeral amputations. iLimb Quantum has digits made from titanium to allow for carrying heavy loads and are gesture controlled that allow for changing grips.
These iLimb hands consist of myoelectric sensors for picking up residual limb signals to provide users with the input required to intuitively control the prosthesis. Sensors in the iLimb also recognise thumb position to prevent damage during different grip modes.
BEBIONIC HAND
The BeBionic myoelectric hand resembles the iLimb in terms of function and was designed to be an economically affordable hand with similar performance. The foldaway fingers have a fixed movement relative to each other. It provides the user with 14 gripping options and can be used with different wrists. It has proportional control with individual finger motors for natural movements.
TASKA HAND
TASKA hand is water-proof with knuckle breakaways allowing overloading without any damage. The patented laterally compliant “flexible” fingers enable the hand to grip a wider range of objects. Fingers are flexible and can spread laterally, with individual motors controlling each finger movement. TASKA hand has 3 core grips – general grasp, pincer grasp, flexi tool; and 4 accessory grips – key grip, tripod grip, precision grasp and hook grip. It has a motorized thumb that improves grip transition speed. It has a flexible wrist that can be locked in 3 positions and offer center-biased free flexion. It has a low profile wrist option that allows the waterproofing to be extended up the socket. The LP Wrist allows mechanical rotation upto 90 degrees. However, a major drawback is that the TASKA hand only features passive flexion and rotation.
MICHELANGELO HAND
It has an opposable thumb that is positioned electronically. The Michelangelo hand allows the user to perform activities using different types of grips such as the lateral grip, tripod grip, pinch grip, opposition, abduction and adduction of fingers as well as full and half open palms. The Michelangelo software and EMG processors use a user interface that is intuitive and graphical, that easily predicts the controlling power of the hand. The Michelangelo fingers are similar to human MCP joints such that they consist of a single finger segment actuated only at a single point. The Axon Bus System (AXON stands for Adaptive eXchange Of Neuroplacement data) has an integrated data transmission system which is also the basis for the control of the Michelangelo Hand. The individual components are optimized to operate in harmony and work with each other to eliminate any delay that may occur in the speed and functionality of the Michelangelo Hand.