Low-Cost Electronic Prosthetic Hand project
South Korea, Syria
a device / 2015~
variable size
EGM, Electrode, PLA, bolt, nut, silicon, wire and others

Mandro is a company that develops low-cost 3D printing electronic prosthetic hand under the principle “No one cannot use electronic medical devices because there is no money.” When CEO of Mandro started his 3D printer business, In 2015, the company started development in the wake of the story of a young man who lost two arms in his work. The development aimed to create a prosthetic hand for about $ 800. And now it is sold for about 1200 dollars. With the help of governments and world organizations, the corporation is helping those in need in Korea and those who lost their hands in the war in the Middle East.
From 2015, I helped Mandro to complete products. I also am developing artificial skin for a prosthetic hand. It aims to produce in 2019. Recently, the prosthetic hand of Manduro cooperated with Swisslims to advance into Africa, like Tanzania and Uganda.

Mand.ro Prosthetic Hand Maker – Activity Report in Jordan Office 1

2018

2017

Introduction of Mandro’s Electronic Prosthetic Hand

When Mandro first planned the production, we expected 2 ~ 4 weeks of the production process for one person. However, as we proceeded to produce the product, we were encouraged by many people to think about what is truly valuable. We felt that helps for only a minimal number will eventually be hopeful torture for the remaining tens of thousands of people, so the principle of “no one who can not write the number of electrons because there is no money” was applied to Mandro’s business.

Mark 1(2015.01.24)

Mark 1.5(2015.02.24)

Mark 3 (2015.04.03)

Mark 4.5 (2015.09.12)

The development of the prosthetic hand has evolved 11 times.

The Composition of Mandro’s Prosthetic Hand

3D Printing for Mandro’s Prosthetic Hand

The overall appearance of the electronic prosthetic hand is printed on a 3D printer. This means you can make a prosthetic hand anytime, anywhere.

Assembly of Fingers and Installation of Motors

Five small motors provide the power to move each finger.

Sensor Circuit

A self-developed PCB sensor circuit detects weak muscle signals in the severed arm.

EMG Sensor

A self-developed dry electrode is used to stably receive the EMG signal.

Gloves of the Prosthetic Hand

Custom-made fabric gloves are used to provide anti-slip and functional enhancements.

Customizing Sockets

3D scanning, modelling, and printing have introduced low-cost customizable sockets

Electronic Charger

For charging and storage of electronic prosthetic hand, just place it as the world’s first stand of the electronic prosthetic hand, and the charge is completed in one hour.

Future direction

Many users in the Middle East and South Korea are now looking for sustainable development directions. One of the developments is the skin of the electronic prosthetic hand.

Skin Work (Operation) of Electronic Prosthetic Hand

The Mandro’s electronic prosthetic hand has both scalability and limitations at the same time because it’s made from a PLA 3D printer. Although 3D printed and assembled on a 3D printer at any time and from anywhere, it is likely to be contaminated in an external environment and it is no friction when grabbing objects. For solving the frictional force, I use a rubber pelvis which is installed at the tip of the finger.I have worked to solve the two problems which were mentioned above, and additionally to create an artificial surface of a hand similar to a real one.

Modeling Work for Electronic Prosthetic Hand

It is a modelling task to determine what kind of type to create before the mass production of latex artificial skin with a metal mould.

1. Electronic prosthetic hand coating

I filled up the empty space with coated non-foaming hard urethane material. Then, using the epoxy putty, a large space not to be caught by urethane was bridged.

2. Primer

I filled the fine section again with the primer, checked again, and identified the section that needs to be filled.

3. Change of the joint part of the modelling for the skin of the Electronic Prosthetic Hand

For solving the problem of gloves pushing up gloves or weakening the strength of artificial hand by frequent exercise when tested with latex medical gloves, a folded shape was modelled that looked like a staircase in a joint. It was made in the prediction of tighter and more accurate for mass production.

Artificial Skin Test of Electronic Prosthetic Hand Using Silicon

For ease of testing, skin production of electronic prosthetic hand was tested with silicon.

1. Quantitative testing of various softener

I tested silicon with a softener. The thickness that can be reduced by hand was between 5.0mm to 1mm. I experimented with different amounts of softener. Adjusting the amount of softener was important because large quantities of softener weakened the strength of the material.

2. Optimized electronic prosthetic hand skin

The colour of each material was different, but the artificial skin made of red colour with the added 5% softener showed the appropriate flexibility. The strength of the rubber band on the fingers of the prosthetic hand is applied differently, in order, from the thumb to the small finger. According to the test result, the strength decided middle finger was the most appropriate. If the strength is too strong, the speed of spreading the hand is too fast and the force is too strong thus there has a problem when it is grabbed a particular object.

3. Artificial skin test of real skin and thickness

I tested it when the skin of the artificial skin like a human hand was made thicker by 2mm. Since the thickness of the silicon becomes thick, the elasticity is lowered. When a prosthetic hand grabbed its fist, I had to put 2% more of the softener on the artificial skin because it bumped into each other and obstructed its fist from being held.

Current Stage of Development of Electronic Prosthetic Hand Skin

Mass production of the skin was delayed and replaced with cloth gloves as the form of the prosthetic hand continued to develop. In recent years, the form of prosthetic hand has become the first stage of completion and plans to produce skin 1 version in early 2019. In an interview with people who needed a prosthetic hand that I met through the first, I aimed to develop cheap and functional skin without problems because the physician demanded the functional function of the hand rather than the real thing. However, as the business of Mandro has expanded to foreign countries like Syria, I have found that there is a lot of demand for similar goods as the real thing. And technologically advanced, we are expecting customized skin and skin through 3D scanning. The result of the second test is awaiting the application. Those who use Mando’s prosthetic hand are very helpful to development.