For meeting the given criterions while making sure innovation and comfort of the wearer is taken care of, we came up with design, “The Bellower.” This is a below the arm prosthetic which moves the gripper section using a wire connected from the biceps of the wearer. The wire gets stretched while opening the elbow and the gripper opens. The gripper is given a hole of 1/2″*20 as mentioned for the male bolt to mate with. Entire gripper will be kept in place using torsion spring situated in the top of the gripper index finger.
The main feature of this design is the ability to adjust for forearm length. This is achieved using concentric cylinders which mesh using a paper cutter like mechanism. On the insides, 2 sliding shoes with torsion spring keep the cylinders locked. This provides rotate-adjust-lock in type of mechanism for adapting this design to children arms as well as adult arms.
The adapter part is done using the foam padding cup for minimizing irritation to the wearer as well as a hook and strap belt goes all along to tighten the 5 pairs of flaps holding the design. The bicep belt is made up of hook and strap material too to ensure easy removal from one hand.
Due to lack of time and other personal factors, I am not able to make the above the arm contraption but it would be equipped with this length adjustor mechanism too for adapting to various amputation lengths as well as various arm sizes.