September 25, 2022
(crédito: Brandon Martin/Universidade Rice/Divulgação)

Learn how the “extra hand” developed by American scientists works

9/12/2022 at 5:58 AM / Updated 9/12/2022 5:59 AM

(Credit: Brandon Martin/Rice University/Handbook)

An elderly person who struggles to hold things using their own abilities can rely on a new technology attached to the hip to help carry light objects like a bottle of water or a set of keys. George R. at Rice University in the United States. That’s what mechanical engineers at the Brown School of Engineering are planning. They created an “extra arm” that was accessible and – because it was placed on the body – easy to recharge. This is because the entire mechanism is powered by the mechanical energy generated when the wearable user walks.

“We believe our device will help users with functional limitations, including the elderly and the disabled, to pick up small household items, especially when their hands are busy,” said Anoop Rajapan, a postdoctoral fellow at Rice University and one of the researchers. Lead authors of the project. , detailed in the journal Science Advances. The technology has been tested with objects weighing up to 60 grams.


The mechanism is energy self-sufficient, powered by compressed air from a textile pump placed in the wearer’s shoe. When a person walks, he creates energy with the power of his legs, which compresses the pump. This compressed air is carried through a tube to a wearable energy storage bladder, which is attached to the user’s waist, which is triggered whenever needed.

All prosthetics, whether automated or mechanized, require some form of power source. Usually, a battery is used. Pneumatic devices that use air pressure as a driving force, a mechanism used by the Rice University team—require an air cylinder, a small motor, or a compressor that compresses air.

Instead, American researchers developed a simple technology that would be powered from the power used to pump the air during certain passes. “It takes approximately three minutes of walking to fully fill a wearable energy storage bladder,” emphasizes Daniel Preston, assistant professor of mechanical engineering at Rice University and author of the study.

Alexandre Lasthaus, an electronic engineer and professor of mechatronics engineering at the Universidade Presbiteriana Mackenzie in São Paulo, focuses on the convenience of the mechanical hand. “Usually, I see prostheses with electric motors, lots of wires and batteries, which are usually not very comfortable. It’s completely wearable and very discreet, so this device seems relevant to everyday life,” he says.

Mechanical arm power
Mechanical arm power
(Photo: Waldo Ganni)

Flexible and washable

A prototype developed by the team is designed to roll and hold objects. It rests on a strap when not in use, and extends when activated. The flexibility of the nanotechnology textile material allows the device to adapt to objects of different shapes. The neck has a thin rubber coating on its surface, improving contact grip with soft and slippery textures.

According to the creators, the price of the device is US$ 20, about R$ 100. In addition to being cheap, the product is simple and can be cleaned in a regular washing machine. Additionally, the energy capture device can be inserted into any shoe without creating discomfort while walking. “The pump is available in different sizes and can be modified for different users, if needed,” Rajapan explains.

The energy harvesting system provides a maximum average power of three watts (W). According to Preston, the technique can be extended to other types of pneumatic actuators, devices that convert the energy of compressed air into mechanical motion. “Any pneumatic device compatible with this power level will be powered by this system,” he says. The engineer expects future versions to include sensors capable of capturing the user’s intent to activate the arm and complete the movement.

*Trained under the supervision of Carmen Sosa

Two questions

Paulo Henrique Araujo is head of orthopedics at Hospital Sírio-Libanês in Brasilia.

Paulo Henrique Araujo is head of orthopedics at Hospital Sírio-Libanês in Brasilia.
Paulo Henrique Araujo is head of orthopedics at Hospital Sírio-Libanês in Brasilia.
(Photo: Personal Archive)

How will this new technology impact the field of orthopedics?

Patients with orthopedic problems in the upper limbs, who have lost strength, are immobilized by surgery, or have an upper limb disability, can use this technology to carry objects. The impact it brings is precisely that these people will not be completely passive. Obviously, this type of technology doesn’t allow you to practice in sports or other slightly more complex situations, but for trivial, day-to-day, it helps because it’s cheap and lightweight technology.

Is the developed hand a viable alternative for patient recovery and assistance?

I believe this is the most applicable alternative in aid. This arm will help the patient to carry things that he cannot because of the situation he is going through when he is recovering from a problem or disabled. In terms of recovery from surgery, I think this is the responsibility of the rehabilitative physiotherapy area. So, I think the importance of helping the patient carry on with daily activities of carrying things can best be described by this hand developed by researchers at Rice University.