Students Invent Noninvasive Brain-Controlled Upper Extremity Prosthesis

Two undergraduate biomedical engineering students have developed a
prosthetic arm that is controlled by brain signals. The Artificial
Muscle-Operated (AMO) Arm is powered by artificial muscles to create movement.

  The Artificial Muscle-Operated Arm uses brain signals to create movement.
  The Artificial Muscle-Operated
Arm uses brain signals to create movement.
  Image: James Kachan

Thiago Caires, third-year student at Ryerson University in Toronto, and
Michal Prywata, a second-year Ryerson University student, wanted to create a
device as functional and available as the best prosthetic but with full
external control and without the requirement of surgery.

“We looked around at what is available on the market,” Caires
told O&P Business News. “We found this big gap in
brain-controlled prosthetics. There are only limited solutions
available. There is muscle innervation surgery where you go through the
expensive surgery, then after 8 months of a healing process you are fitted with
a basic prosthesis. Most upper extremity amputees are using devices that are
activated by body movements with some kind of strap and a hook at the end of
the arm.”

The AMO Arm makes use of signals in the brain that continue to fire even
after a limb is amputated, according to Caires. Users wear a headset that
senses a signal and sends it to a miniature computer in the arm. The computer
then compares the signal to others in a database.

“The headset is placed on the head, and brain waves are measured by
voltage signals called biopotential difference,” Caires said. “That
signal gets measured and sent. If you think about one motion that has a certain
pattern, that pattern gets recorded, saved and restored on the database within
the arm during the calibration process. The next time the person thinks of a
similar pattern, it triggers that motion.”

According to Caires, through simulating the expansion and contraction of
real muscles, the system makes use of compressed air from a small, refillable
tank in the user’s pocket.

Because the device does not include microelectronics or motors, it costs
less than other functional prosthetic arms.

“Just not having the surgery brings down the costs, including
doctors or specialist visits,” Caires said.

The period of adjustment for new users is also decreased because the AMO
is noninvasive. Caires compared obtaining the device to buying a cell phone.

“You order it online and it comes to your house. Then you open up
the box and you start using it,” he said. “You never know how to use
it right away, but you use it and figure it out. Our device works the same

Caires believes a person can pick up the mind-control technology in 10
minutes. “Users will don the arm for 16 hours a day or more, so they will
understand it quickly,” he said.

As of press time, the AMO Arm is still in the development stage. Caires
is currently working on breaking down the technology to the finger level to
enable users to grip and hold a wide variety of objects. He is developing a
technology where as the hand is approaching an object, a signal change that
goes through the microcontroller on the arm triggers a maximum pressure. The
hand will have the ability to distinguish between an egg and a golf ball and
will allow for the appropriate pressure.

“If you are approaching a block of metal, there is going to be a
different signal than if you were approaching a plastic water bottle,”
Caires said. — by Anthony Calabro

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