Using Mechanical Engineering to Treat AFM

Acute flaccid myelitis (AFM) is an illness that is as inexplicable as it is devastating. The rare neurological ailment, which causes muscles and reflexes to become weak, overwhelmingly affects children. To date, its origins are not fully understood. As such, there is no cure for AFM, and there are few ways to treat the afflicted effectively.

However, a group of students from the University of California, San Diego was able to help one young AFM sufferer by harnessing the power of mechanical engineering.


A Problem Without a Solution

Dr. Ted Ng and Kitty Cheng learned their son, Max Ng, contracted AFM when he was two years old. The boy’s face inexplicably began drooping on one side. Soon afterward, the toddler experienced arm paralysis and weakness in his diaphragm. Subsequently, young Max spent an entire year connected to a ventilator before he was able to breathe on his own.

Over time, Max lost muscle control in his arms and shoulders but retained the use of his wrists and fingers. Sadly, his condition prevents him from doing other things we all take for granted, like hugging his parents and younger sister.

Some AFM patients can use motorized braces to improve their quality of life. Unfortunately, AFM afflicts sufferers in a variety of different ways. In Max’s case, his atrophied shoulder girdle muscles can’t support the weight of conventional braces.

Dr. Andrew Skalsky, a rehabilitation specialist at Rady Children's Hospital, came up with an unconventional idea to help his patient. Dr. Skalsky knew that UC San Diego’s Jacobs School of Engineering requires its students to solve a real-world problem to pass their capstone courses. So, he submitted Max’s need for a personalized mobility solution as a challenge, and the institution accepted.

Ten weeks later, four Jacobs School students produced an innovative new device that changed Max’s life.


Using Mechanical Engineering to Address a Medical Issue

The aspiring engineers understood that helping Max required them to develop a lightweight harness that distributed weight evenly. The group created a functional design by running a host of computer simulations and fashioned a series of prototypes using a 3D printer.

Eventually, the quartet made a polyester and aluminum rig fitted with ultra-lightweight motors called linear actuators. The comfortable harness distributed the weight of the device across Max’s torso. Furthermore, its material was stretchy enough to allow the youngster to have a wide range of motion. Plus, its braces gave Max the ability to lift a pound-and-a-half of weight, while only weighing 30 grams.

The UC students also used their coding skills to give Max a high degree of control over his orthopedic brace. The group had flexible sensors sewn into its gloves so that it could detect when he moved his wrists. The quartet then equipped their creation with an algorithm and custom-built circuit boards to translate his motions to its actuators.

Once completed, the highly responsive harness allowed Max to raise and bend his arms. Now, the five-year-old can not only hug his father but playfully spar with him.

While some advances in technology can be dispiriting, it’s essential to always keep people like Max in mind. In the past, his illness would have kept him from enjoying crucial parts of his childhood. Instead, the boy has a much higher quality of life because mechanical engineering succeeded where medicine fell short.


Photo credit: Hayne Palmour IV / The San Diego Union-Tribune

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