Orange-Line

Engineering and prosthetic devices: the brilliant study of NC State University

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Author: Salvatore Corradi – FM Chairman

Living in a condition of disability due to the lack or malformation of limbs certainly involves great changes for these individuals and their families. The experience of amputation in fact represents a traumatic event that has repercussions on the psychological and physical aspect. As regards the physical sphere, the studies conducted in recent years have been decidedly encouraging: fortunately there have been many advances both from a medical and technological point of view, which have contributed to improving the lifestyle of those who need prosthetic systems. Thanks to these devices, the daily life of a patient with amputations has significantly changed, so much so as to lead to gradual levels of recovery which have as their final purpose to guarantee patients as much independence as possible.

Yet, despite the great achievements, many of the amputated people often experience discomfort and pain in wearing prosthetic devices since the stump is often exposed to an uncomfortable environment (think of lower limb prostheses), in which continuous pressure can lead to serious consequences, including ulcers or tissue injuries. For this reason, about 25% of amputated people choose to drastically reduce the use of artificial limbs, thus also giving up an important degree of autonomy in everyday life.

It is necessary to adequately monitor the pressure distribution between the prosthesis and the amputated limb, a region called the inner socket environment (ISE), in order to guarantee the user a correct and long-lasting use of the device. The analysis of this parameter involves a system of rigid strain gauge sensors, available on the market, which are, however, bulky, heavy, annoying and even spatially limited.

In this regard, researchers from North Carolina State University have created a prototype patch, which incorporates a lattice of electrically conducive yarns and connects to a computer, and it could help to detect pressure points in the socket of an amputee’s prosthetic limb. The team comprised researchers in textiles, electrical, computer and biomedical engineering at NC State. In one experiment, the researchers tested whether the patch could detect changes in pressure when they placed it on an artificial limb, turned at different angles. Then they used it to test pressure changes when an able-bodied person wore the sensor patch while walking with a bent-knee adaptor and while shifting their weight between legs.

Next, a volunteer with an amputated lower leg wore the patch on the liner of their prosthetic limb in areas where it typically applies higher pressure. They tested the sensor patch while the volunteer shifted weight and walked on a treadmill, finding the system was durable and could reliably monitor pressure changes in the socket.

Part of their work involved designing the system to be lightweight and small enough for human use. According to the team, they created the sensor patch by sewing the yarns together in such a way that they created an electromagnetic field and applied a small amount of electrical power using a small battery. They found that they could measure the amount of electrical charge drawing the yarns together at each lattice point. The next step is to integrate the sensors into the prosthetic sockets directly or into a wearable object, a change that would change the life of many people.