Open Bionics began selling its 3D-printed Hero Arm one year ago in the UK and France, but now it's available in the US. The start-up, Open Bionics specializes in producing inexpensive, lightweight prosthetics and their arms are inspired by the Iron Man, Star Wars, Frozen and Deus Ex films.


Every prosthetic arm the company designs is built for each individuals shape and size, coming in 3 different hand sizes and 2 different arm layouts. Each Hero Arm contains either a 3 Motor or 4 Motor Hand, depending on the hand size that fits best for the arm. The 3 Motor version has a smaller size than the 4 Motor version. There are two tendons located in the index and middle fingers of Motor 4, allowing them to move on their own. Both index and middle fingers on the 3 Motor version will always move at the same time. Each socket is 3D printed based on a scanning of the user's arm and comes with two differently designed layouts, with an internal or external battery. Both layouts function the same way, but they have some differences in design.


Putting on the bionic arm is easy and comes with a BOA Fit system, allowing it to fit securely. (Image Credit: Open Bionics)

The Hero Arm also comes with a BOA Fit System that makes it easy to adjust, so it will fit the arm perfectly and comes with precise balance control and a secure fit. Adjusting the fit of the Hero Arm is also quite simple. All the user needs to do is adjust the BOA Dial. It also comes with a Li-Ion 7.5V 2600mAh battery and smart charger. Battery life varies, depending on usage, but it's recommended to have it charged every night and requires removal of the battery before charging.


It also comes equipped with an advanced myoelectric, multi grip bionic hand. EMG sensors located in the arm, detect muscle movements with the hand reacting for control. A prosthetic doctor will look for the EMG sensors for the wearer's muscles when putting it on for the first time. The bionic hand can be controlled by tensing the muscles that are used the same way as opening and closing a human hand. To open and close the hand, certain actions must be met. To close, the wearer must flex the wrist inwards and pull their fingers in the hand's heel. Opening the hand only requires the wearer to extend the wrist with an open palm in a stretched position. Small or delicate object manipulation can be achieved easily when the hand moves slowly through gently tensed muscles and through quicker movements with a firmer tense.


How to open and close the hand, as illustrated with the movements of a human hand. (Image Credit: Open Bionics)

There are four different grip patterns in the 3 Motor version and six patterns in the 4 Motor version. The grips are grouped in pairs, making the switches quicker and easier. To switch between grips in a group, the wearer must open their hand, relax it and hold the signal for over a second. A long vibration will be present, and the Hand Button will blink green a few times, letting the wearer know about which grip number they have chosen. The first grip in the group has 1 flash, and the 2nd grip in the group has 2 flashes. Switching between different groups can be achieved by pressing and releasing the Hand Button. A short vibration will be felt, and the button will blink purple a few times, indicating the group that has been selected, following the same sequence pattern as the green blink.


The main group includes both Fist and Hook Grips. The Fist group can be used for carrying circular objects like bottles or fruit, holding utensils and handles. This can also be used to give handshakes. The thumb closes with all four fingers to close the hand. In the hook group, the thumb stays open while the four fingers close, allowing shopping bags to be held or carried around.


The secondary group has two Tripod Grips. These grips are mainly used to picking up and handling smaller objects. In the Tripod A grip, both middle and index finger close, touching the thumb while the ring and little fingers stay open. In the Tripod B grip, both ring and little fingers close together and when the close signal has been activated, the index and middle fingers closer together to touch the thumb.


The final group that can only be used on the 4 Motor hand version has two Pinch Grips. The Pinch Grips can be used when handling or lifting up small objects. It works with the thumb knuckle when it's open and closed. In the Pinch A Grip, the index finger closes, touching the thumb and every other finger stays open. In the Pinch B Grip, all the middle, ring and little fingers will close. When the close signal has been activated, the index finger will close, coming in contact with the thumb. 


Even with all the sensors, motor versions and grip patterns included in the bionic hand, the arm still only weighs less than a kilogram. It can be worn by anyone at a young age, eight years or older.



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