Trying to apply an i-Limb ultra revolution to bake an apple cake.

Baking apple cake as task posed to solve for i-Limb ultra revolution

With the i-Limb ultra revolution quite possibly being about bi-manual empowerment and "the little things" I figured best to start with something feasible. Not vacuum cleaning or cutting hedges or other really hard stuff, but, baking a cake.

All manipulations were rated on a 0-10 scale, 10 being perfect manipulation, 0 being a total fail.

Opening and handling food packs, powders, flour et cetera

I first tried to tear these little paper packs as bimanual tasks:

• baking powder 0/10
• vanilla sugar 0/10
• lemon bits 1/10

By and large, the i-Limb entirely failed to hold small packages so I could rip them open. The grip did not allow that. The lemon peel bits baglet had a little indent to ease the rip, but otherwise the hand did not manage to hold on to that pack either.

One generally will have to use scissors to open all of these which, however, can also be done without the prosthetic hand or with any other prosthetic device. That would put me back on square one or maybe defy the purpose of having all these sophisticated grips.

I then needed to manipulate these other packages bimanually:

• flour 4/10
• sugar 4/10
• butter 0/10

Holding 1 kg paper bags of sugar and flour was no problem. Yet, a reliable scoop was difficult or impossible, and the hand did not manage to hold on to a spoon or anything like it. Pouring the flour was not working that well. 

Manipulating the butter paper - thin slippery greasy foil - was impossible as not even the hardest grasp held on to the paper. I had to ask for help for the butter part because the mess would have been considerable otherwise.

Egg shells were crushed in a massive way. The grip was in no way gentle.

Using a body powered Becker hand I was always able to provide a very gentle and fine motor control of the grip also when handling eggs or egg shells. Not here.

The damage was massive and hard if not impossible to control. Even pushing eggs open with the stump works a lot better than THAT.

• handling eggs 0/10

 

Holding and stabilizing equipment

The holding and stabilizing would contain:

• holding and stabilizing the bowl 10/10
• holding and stabilizing the mixer 6/10

Holding the bowl worked very well. The fingers always managed to apply their adaptive grip with an advantage. Where the hand failed was grasping the handle of the mixer. The diameter of the mixer's handle was too small for that so it would wiggle. Nevertheless, mixing worked out pretty well.

Finding tools in the drawer and getting them did not work at all. The fingers did not offer a stable pincer grip as the tips would fold inwards passively before other tools could be pushed aside to isolate and grab a particular spoon or fork handle. There, the stiffness and precision of a Becker hand or hook was sorely missing.

• grab spoon 0/10
• grab dough scraper 0/10

Putting dough from bowl into cake form would not work at all. There was no way the i-Limb could hold on to the dough scraper - any way, it would fall out. And there was no way the i-Limb would hold on to the bowl either, being slippery and all, and heavy.

• handling full bowl 0/10
• handling dough scraper 0/10

Handling hot cake as when using a hook (metal) was not possible.

• hot cake handling 0/10

Peeling apples

• peeling apples 0/10 (forfeit)

In order to not damage the glove, peeling apples was not even tried. As damaging the glove seems to be a serious event for an i-Limb, possibly voiding the warranty, the i-Limb was deemed to be unfit for that task right from the outset.

However, I will test this with the other prosthetic devices that I have that are uncritical. For example, damaging a Becker hand's PVC glove in no way diminishes its function, functionality or warranty aspects simply because that hand can be soaked, soaped down, ultra sound cleaned and whatnot up to a rather high degree of contamination. It also does not seem to fail when wet or under water, for some reason.

Total

Overall, the i-Limb scored a 25/150. Looks great, but not so much of a help here really. What it did marvelously was holding on to round mid sized objects of average firmness. Projected scores for stump (?80-110) hook and Becker hand (?>100) make me expect that I will be less disabled without wearing an i-Limb when baking an apple cake without special tool or kitchen preparations.

Conclusion

• Off the shelf everyday apple cake baking was not significantly empowered using the i-Limb ultra revolution. It either needs serious add-ons - grip enhancers, et cetera - or it needs an entirely different setup and equipment.
• Next, I should bake one wearing the Becker hand. Then, a hook. Just to see where we're at. Actually I again sorely missed my body powered arm which I did not have close by there.
• The i-Limb is, based on actual experience, not a hand to be recommended for the little things, nor for everyday tasks such as simply baking a cake. Maybe it works better in societies where self sustaining meal preparations are given up in favor of ordered, pre-cooked, pre-prepared or over the counter food.
• But it still looks great and in all its glory, its promise keeps being absolutely immense. It hurts deeply to realize that it failed so much, trying to bake an apple cake. If a hook fails, that does not hurt, one dismisses that with a scoff. Not here. It really pains me to see this beautiful wah-wah-hand being so unable, manually speaking.

Possible solutions

Some problems that I encountered are typical for the myoelectric control, such as crushing eggs. Other problems are typical for the hand design, such as being unable to get a spoon from the drawer or being unable to hold a paper bag.

To improve the experience:

• get butter in plastic container (but not butter wrapped in foil)
• cut open paper bags using knife or scissors (rather than trying to use bimanual grips to rip them open)
• wrap thick tissue around tool handles (so prosthetic hands can grip better)
• hang tools from tool hooks or wall mount (rather than keeping things in drawers)
• use heat insulating glove or tissue or fabric (to handle hot stuff)