Why Ortho

Why does Robohand use Orthoplastic as opposed to other components?

One of the many questions that are asked of Robohand is why do we use medical grade Orthoplastic for the molding and fitting of the gauntlets for Robohand, when the cost of Orthoplastic is high and the idea was to keep Robohand as cheap as possible?

Besides Robohand making functional mechanical devices available to the public Open Source, our first motto is “Do no harm”. There have not yet been extensive studies relating to how these devices react with the body due to the fact there has never been anything like this available before.

When attaching a device to your body, you need to ensure that it fits correctly and that there is no chaffing which will cause abrasions, sores and scarring on the soft areas of your skin. If there is too much “wiggle room” the device will not function properly and this leads to it not being used by the wearer.

“Your skin is the largest organ in your body. It’s also one of the most important. Why? Your skin performs essential functions like temperature regulation, hydration and protection against invading bacteria.” (Ref: http://health.howstuffworks.com/skin-care/information/anatomy/skin-graft.htm)

“Skin is a seamless organ, like a fine cloth protecting valuable assets. Imagine a piece of silk. Just one small tear can make a big difference in how it looks. And it’s the same with skin. Any burn, injury, or other trauma, such as surgery, can cause a scar.” (Ref: http://www.webmd.com/beauty/skin/cosmetic-procedures-scars)

Orthoplastic has been designed by medical professionals to allow your skin to breathe. It is called “open cell”. Even though we are able to heat it up, mold it and change its structure and have it harden again, it remains open cell and breathable. If you have experimented yourself with long term wear of leather for example, you will notice that it absorbs sweat and will begin to smell. Leather is not washable as this affects its malleability. Leather also deteriorates with age and use.

With the design of Orthoplastic being open cell, one does not sweat. It is washable in luke warm water and does not change its shape. Velcro, which is rough, can suffocate your skin, chafe and cause abrasions and scarring. A material like Velcro needs to be tightened against the skin which could cause restrictions to blood flow and swelling. Using Orthoplastic ensures that the limb is enclosed in a safe cocoon. Orthoplastic is non-toxic, resistant to detergents, easy to keep clean and unaffected by all common acids and solvents.

In our example below, to show you some of the issues that Robohand have faced, and why we use medical grade Orthoplastic, we introduce burn victim Sky*. Sky was involved in a fire when she was very young and underwent several surgeries including skin grafts.

Skin grafts are often used for burn patients; skin is removed from one area of the body and transplanted to another. There are two types of skin graft: split-thickness grafts in which just a few layers of outer skin are transplanted and full-thickness grafts, which involve all of the dermis. There is usually permanent scarring that is noticeable. (Ref: http://www.webmd.com/skin-problems-and-treatments/plastic-surgery-burns)

Skin Graph

“Scarring is a natural part of the healing process after an injury. Its appearance and its treatment depend on multiple factors. The depth and size of the wound or cut and the location of the injury matter. So do your age, genes, sex, and ethnicity.” (Ref: http://www.webmd.com/beauty/skin/cosmetic-procedures-scars)

In the picture below, you can see on the back of Sky’s hand how much scarring has occurred. (Some areas are not as sensitive as others.) When fitting with Orthoplastic you can ensure the molding takes into account the shape of the hand, the movement of the wrist and whether there will be chaffing. If you are going to use a 3D printed gauntlet that is a standard size and does not mold to the body, this could cause friction and further injury.


“Keloids are scars that continue to grow even after the skin has healed. They rise above the rest of the skin, and they usually have a smooth top, are tough to the touch, and have a pink or purple color. Keloids are irregularly shaped and tend to enlarge progressively. Learn what you can do to minimize their appearance.”  (Ref: http://www.wikihow.com/Get-Rid-of-Keloids)

If you look on the palm of Sky’s hand in the picture below, you can see the long misshaped keloid that has developed. On the right you can see other keloid’s that have also developed over the “good” skin.

Before being fitted with a Robohand, Sky will need scar management on her hand to soften the keloid and allow more flexibility. If the keloid is left to continue its growth, it will eventually tighten the surrounding skin reducing her mobility.


For more information on keloid’s visit: http://www.patient.co.uk/health/keloid-leaflet

Because Orthoplastic has such great medical properties, Robohand can be used in the swimming pool, the shower or bath and does not have any limitations except extreme heat. Do not leave your Robohand in the car in the sun as both the 3D printed parts as well as the Orthoplastic can warp due to the intense heat as well as become brittle.

Please see our Blog post from an independent Biomedical Design Professional on the use of Orthoplastic: http://www.robohand.net/2013/12/a-response-to-the-open-letter/

For more information on Orthoplastic visit: http://www.wisegeek.com/what-is-an-orthoplast.htm

*Names have been changed