Double Amputee - PJ Prosthesis

Double Amputee - PJ Prosthesis - open-source assistive technology prototype by the Singapore community

About this project

The PJ Prosthesis Double Amputee Module (aka Boonsthetic) is an easy to use Prosthetic hand for Bilateral BE (amputation below the elbow on both the hands) made from readily available and cost effective materials. Read more on Product Specs and Development History in Resources.

The challenge

Bilateral BE Amputees do not have fingers for gripping objects, so they rely on the pushing and pulling motion of the forearm for functionality. The TOM: Singapore team was challenged to develop a low-cost prosthetic module based on the initial PJ Prosthesis design that would generate greater performance and dexterity from these simple forearm gestures. Specific functional requirements included a prosthetic hand that would enable Boon to independently and hygienically lower his pants for passing stool, wash himself with aid of a water sprayer, and pull up his pants when done. Read more about the product development history in Resources.

Who it helps

Tan Whee Boon (54) is a young man from Singapore who lost all four limbs to flesh eating bacteria. As a new Quadruple Amputee, Boon was totally reliant on his caregiver for routine tasks and hygiene. So in 2019 Boon sought out TOM to develop a device to regain his indepence when using the toilet and dressing himself. Boon is a married man and a father of two, who enjoys playing wheelchair rugby in his free time.

How it works

Product Specs

Approximate Cost: SGD $91

Time Required: 2 Days

The PJ Prosthesis Double Amputee Module is a modular prosthetic arm based on the PJ Prosthetic arm platform (read more in developer history below). The device includes four main sections: (1) Bicep Section, (2) Forearm Section, (3) Clip, (4) Pulling String.

The Bicep Section, Forearm Section and Clip are 3D printed.

The Bicep Section has an internal layer of cushion tape to maximize comfort.

The Forearm Section includes three sets of Velcro for holding the forearm firmly in place.

A rotary joint is used to connect the Clip Section to the Forearm Section, and can be rotated horizontally at a 60 degree angle. After fixing a desired angle, the joint can be made immobile by tightening the screw cap.

The pulling cable is a simple bicycle brake wire, which is rolled at one end and covered with tape for pulling comfort.

To follow updates on PJ Prosthesis, other assistive tech solutions by TOM communities and our global network of makers, follow us on social media here .

Product Development History

PJ Prosthesis is a universal platform that enables continuous development of modules and attachments, both custom-made and generic, to accommodate a wide array of functionalities and features for different users of different sizes.

Development of the PJ Prosthesis platform began in 2018 when TOM’s Tel Aviv community created a lightweight yet durable 3D printed prosthetic arm for IDF veteran Noam Guez. After losing his left arm in basic training, Guez wanted a comfortable device to regain his independence in daily tasks and beloved hobbies like cooking (especially Shakshuka) and painting.

TOM: Singapore adapted the platform in 2019 to accommodate the needs of Tan Wee Boon, a Quadruple Amputee who lost his limbs to a flesh eating bacteria, resulting in the PJ Prosthesis Double Amputee Module. This new module employs generic functions for double upper-limb amputees, such as easily attaching and removing the device independently using a pull string, as well as tailor-made sizing and functionality to allow the user, Boon to shower and use the toilet independently. Additional developments in Singapore include refining the prosthesis base to boost appeal and creating a grip for holding spoons and bottles.

The Singapore Developer Team includes: Tan Whee Boon, D J Saravana Kumar, Daniel Levy, Luis Sacco, Zhang Xingzi, Joan Toh Yuet Meng, Chia Zhen Da, Tan Juay Yong.

Most recently, TOM: Shenkar outfitted the prosthesis with two new specialized attachments to the modular limb to allow Yael and Itamar (27) in Israel to play the violin and drums respectively.

“TOM communities hope to develop multiple product lines of modular device attachments for PJ to enable amputees to regain freedom of function and pleasure in the arts, crafting and more,” says Daniel Levy, Head of TOM R&D. Levy heads the development of PJ, along with two other industrial designers from Tel Aviv.

See the PJ Prosthesis Violin Attachment here .

PJ Prosthesis has been featured in Channel News Asia , the Jerusalem Post , and Baltimore Jewish Life .

Project details

The build files for Double Amputee - PJ Prosthesis are free to download from this page - open source, shared by TOM: Tikkun Olam Makers.

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