ACL Rehabilitation Mat

Student athletes Ashley Rayzer and Ayanna Townsend are dynamic collaborators—on the court and in the classroom. As members of WT’s history-making Girls Basketball team, they helped score a record-breaking season for the Bears. As project partners in Graig Marx’s Research Science class, they engineered the ACL Rehabilitation Mat —a novel device that supports users recovering from knee injuries, especially ACL tears or sprains.

“The inspiration for this idea came from my experience with ACL injuries,” says Ashley, whose first, the result of an eighth grade skateboarding accident, sidelined her from sports for a year while she underwent physical therapy. One year later, she was benched again. “As soon as I started basketball season that winter, I tore my other ACL. This was extremely discouraging for me as an athlete. I didn’t understand how I could have injured my other knee after all the time and effort I put into strengthening them.”

Because females are up to 10 times more likely to suffer anterior cruciate ligament, or ACL, injuries than males, likely due to anatomical differences such as hip width and knee structure, Ashley and Ayanna designed the ACL Rehabilitation Mat especially for teenage girls. The interactive tool features placement diagrams, pressure sensors, and LED lights that provide direct feedback as users perform exercises—“so a physical therapist would not have to be present while users go through the therapy process,” notes Ayanna.

Wearing a knee brace fitted with an ultrasonic sensor that detects knee movement and distance, a user steps onto the mat’s foot-shaped diagrams. Mat sensors assess placement; if incorrect, a red light shines, if correct, a green light glows. The user then performs a squat. If done correctly, the green light remains; incorrect performance activates blue, yellow, or red lights. A buzzer sounds if knees move too far inward. Through repetition, users learn proper form that eventually becomes muscle memory, thus lowering the risk of re-injury.

The duo spent spent five months researching before creating a prototype. A key focus: studying human anatomy, particularly how different parts of the body affect knee stability. They also learned how to strengthen knees—and supporting body parts—to prevent re-injury, and consulted with knee specialist Dr. Kelley Fitzgerald about the importance of knee position when exercising.

Next, Ashley and Ayanna applied CAD modeling, 3D printing, wiring, and computer coding and programming skills. Capsules were designed and 3D printed to contain strategically-placed sensors programmed to respond to pressure and activate corresponding LED lights. “For example, if sensor one represents the toe and sensor four represents the heel,” explains Ayanna, “and you are squatting and more pressure is applied on sensor one than on sensor four, we can infer that the squat is being performed on the user’s toes, which is wrong. The serial monitor on the computer reads this, and the red LED light comes on.”

At Pittsburgh’s TechShop, the students calibrated sensors and decided how to measure distance—critical to the ability of the knee brace’s ultrasonic sensor to accurately calculate space between the knees. Programmed to correspond to the average teenage girl’s shoulder width, around 14 inches, the sensor activates a buzzer and red light to signal incorrect technique when the distance is less.

“A lot of lessons were learned during this process,” Ayanna reflects. “Patience…and I had to learn not to stress because everything couldn’t be done overnight. When we would leave class some days, I would feel unaccomplished, and I had to remember there’s always tomorrow—until the STEM Symposium, of course.”

Adds Ashley, “I learned that I enjoy being faced with problems because they help me evolve and gain more experience in what I'm working with. When we faced a problem, we were forced to pick it apart to discover the issue in order to resolve it. This helped me have a better overall understanding of the technology that went into the mat.”

Indispensable lessons that apply to the science lab, the basketball court—and throughout life.