Vietnam university student creates super cheap prosthetic arm

By Pham Linh   October 9, 2018 | 08:32 pm PT
A 23-year-old engineering student in Quang Ngai has designed a robotic prosthetic arm that costs a fraction of the normal price.

Ngo Van Det of Pham Van Dong University in the central province devised the arm using microprocessor boards, motors and pressure sensors for a contest held by his university in which he won the second prize.

Ngo Van Det and his robot arm for the disabled. Photo courtesy of VnExpress/ Thach Thao.

Ngo Van Det with his prosthetic arm. Photo by VnExpress/ Thach Thao

Made of 3D resin, it only costs VND3 million ($128) while similar products around the world usually cost thousands to tens of thousands of dollars.

Det said Vietnam has hundreds of thousands of disabled veterans and accident victims without arms who have great difficulty carrying out their daily activities.

The majority are also poor, meaning they cannot afford to buy prosthetics, and this motivated him to research into bionics with the hope of making inexpensive products of the same quality, he said.

To make an arm and hand for a person, he uses a 3D scan of their other arm and hand to get the design just right since each person’s anatomy is unique, he explained to VnExpress.

The thumb is designed separately to enable rotary movement. Each finger has two knuckle joints – humans have three – except the thumb, which has only one. The palm of the hand has five joints to connect with the fingers.

The robotic hand has microchip and servo motor inside. Photo coutersy of VnExpress/ Thach Thao.

The robotic hand has microchip and servo motor inside. Photo by VnExpress/ Thach Thao

The most elaborate part of the frame is at the triceps, and it requires great accuracy since it is where the prosthetic arm is attached to the wearer.

After a plastic 3D printout is made, the microprocessor board and servomotor are inserted.

The pressure sensor is placed in the user’s bicep. When they exert pressure on the sensor, the signal is transmitted to the microchip and the motor pulls the wire to flex the fingers. Depending on the size of the object they want to grip, varying amounts of pressure are generated.

"In order for the hand to simulate gripping movements, I use flexible elastic pins to connect the knuckles with the palm of my hand.”

Charging the arm is easy for users.

The process of creating the prosthetic took eight months. He struggled with the pressure sensor because the robotic fingers did not have the gripping ability he wanted at first.

Repeated assembling, experimenting and testing meant his first cost him VND6 million ($257). The second one cost half as much.

Minh experimenting Dets invention. Photo courtesy of VnExpress/ Thach Thao

Minh experimenting Det's invention. Photo by VnExpress/ Thach Thao

Tran Tan Minh of Tu Nghia District, Quang Ngai Province, who tested Det’s prototype, does not have a right arm. He could not manage many things without the help of his family, but now, with the new arm, he can.

Pham Truong Tung, a lecturer at Pham Van Dong University, who supervised and evaluated Det’s work, praised it and said though it may not be a new invention it has the potential for development.

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