MIT | roboticsfinder

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One of the great challenges in biotechnology is interfacing synthetic materials with biological ones. Our bodies are designed with an extremely complex network of tissue, vascular, and neural structures to protect us and alarm us if there is something potentially dangerous to our system. If we sit for too long, for example, we feel discomfort and shift positions instinctively. If something is pressing against our leg and threatens to disrupt normal blood circulation, we perceive this threat with pain and pressure and respond accordingly.

Amputees and prosthetists have long been facing the issue of how to interface the residual limb with a prosthetic socket. Fitting for a prosthesis introduces a synthetic limb component to a biological one, and an improperly fitted socket can cause pain, pressure sores, and expose a residual limb to infection and tissue damage. And while there has been much improvement from the crude iron prosthetics that amputees once had to endure, there is still much room to improve to make the interface closer to a natural one.

One group at MIT has sought to address this disparity by developing a variable impedance prosthetic (VIPr) socket. Using MRI imaging and surface scanning techniques, researchers were able to find the tissue depth and where the socket was most likely to place pressure on the irregular bony areas of the residual limb. A socket was then 3D printed using this data to apply the least amount of pressure when fitted to the amputee.

After testing this socket on a below knee amputee, it was found that there was a 7-21% decrease in pressure on various bony areas of the leg compared to a regular socket during walking. While there is still no perfect socket or prosthetic interface for amputees, this is a step in the right direction to protect valuable and vulnerable human tissue.

For those with diminished strength or function of the hand, daily tasks that we often take for granted may become difficult, essentially disabling someone in their daily life. To address this and increase efficiency of the performance of the hand, researchers at MIT have developed “Supernumerary Robotic Fingers,” a type of wearable robotic device with two extra fingers to complement the grasping function of a regular hand.

In normal human movements we have muscles that work synergistically, meaning that there is a central signal from the brain that allows them to contract together to create a certain movement. For example, when the biceps contracts to bend the elbow, the muscle brachialis contracts as well to help facilitate this movement. This allows for efficiency of tasks in our body.

An article titled Bio-Artificial Synergies for Grasp Postural Control of Supernumerary Robotic Fingers explains how the researchers have developed an algorithm to allow the robotic fingers to work synergistically with human hands. That is, the extra fingers are designed to correlate with the human movements to work as an extension of the human hand and enhance activity to form essentially a seven-fingered hand. The researchers use the concept of “Bio-Artificial Synergy.” Thus, the researchers have essentially developed extra fingers that replicate the movements of muscles in the human hand.

The device is mounted on the wrist, and through a sensor glove receives a signal from the hand and works alongside the five fingers to assist with grasping objects. The robotic fingers are longer than human digits, making it easier to grasp larger objects. Each robotic finger can move in 3 different directions. For those that have difficulty holding onto objects or performing coordinated movements, this can be an invaluable tool to perform tasks independently.

Because of these extra fingers, the user is able to perform tasks that are normally difficult to perform single-handedly, such as twisting open a bottle cap, holding a tablet and typing, This product is still in the development phase, and though researchers have amazingly been able to correlate the robotic hand angles with human hand angles for grasp, they have not yet completed algorithms for fingertip forces.

The article mentions that this devices has implications not only for elder care, but for construction and manufacturing.

See the video below for more description of this amazing device:

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3D Printing for Prosthetics: VIPr Socket

Robotics for Elder Care: Super-numerary Robotic Fingers