Three biomedical engineering seniors in the School of Engineering & Applied Science at Washington University in St. Louis, MO used a 3D printer to design and create a robotic prosthetic arm out of bright pink plastic for a teenage girl for a total cost of $200, a fraction of the price of standard prosthetics, which, they say, start at $6,000.

The girl lost her right arm in a boating accident when she was six years old. She learned to write with her left hand, but found most tasks difficult to accomplish with her old prosthetic arm. They new arm, she said, is easy to manipulate. And, it’s her favorite color, which she requested. By moving her shoulder, she can direct the arm to throw a ball, move a computer mouse, and perform other tasks.

The students developed the robotic hand as part of their engineering design course with Joseph Klaesner, PhD, associate professor of physical therapy at the School of Medicine. Several local medical practitioners, including orthopedic hand surgeons, served as mentors.

The student design offers two key design differences that set it apart from similar “Robohand” devices that have been invented recently; it has a motor and a working thumb. The prosthetic is battery-powered and controlled with an accelerometer. The thumb moves with a slightly different trigger (compared with finger motion).

Prosthetic limbs can be tricky for patients of any age, and especially children because they’re still growing and need to move to larger-sized devices on a regular basis. While 3D printers can cost about $2,500, they are capable of producing artificial limbs at a relatively low individual cost.

The prosthetic hands are inexpensive, can be remade when the child grows, and they offer functional abilities.