Prosthetics aren’t cheap, especially if they’re dynamic and not simply hunks of inert plastic. We have featured a number of incredible robotic prosthetics over the years, but the truth is that those are almost always very expensive prototypes that most people don’t have access to. In some countries, like the United States, health insurance companies might not even cover the cost of a basic prosthetic. That was the situation Ian Davis found himself in after four of his fingers were amputated in 2018. Fortunately, Davis is a mechanical engineer and is building his own prosthetic hand that looks straight out of The Terminator.
Davis was suffering from a form of cancer called Multiple Myeloma, which can cause bones to weaken, when he broke bones in his hand as the result of a shop accident. Eventually, doctors were forced to amputate the four fingers of his left hand. His shameful insurance company refused to pay for a prosthetic, because his palm was still functional and they didn’t think his fingers were “medically necessary.” While still confined to his hospital bed, Davis started sketching designs for his own DIY prosthetic. As soon as he was able to get back into his home shop, he started work on those designs.
Many iterations of the design are featured in videos on Davis' YouTube channel. The version shown in his most recent videos is machined from aluminum, and can operate completely mechanically. When Davis moves his hand or wrist, a clever series of linkages transmits that movement to the fingers. Chains on the fingers cause them to curl closed, and springs open them back up when tension is released. Davis does have plans to add electronic clutches to lock individual fingers in place. Those will be controlled by an ESP32, which will monitor muscle flex via sensors. But, even at the current point, Davis' prosthetic hand looks absolutely fantastic and seems to perform very well — almost certainly better than what a decent insurance company would have provided.