One of the on-going problems in this project has been finding glue which can be used to attach the latex insert to the plastic space bags and create an air and water-tight seal. After  lots of experimentation using many different types of glue we decided to change our approach and instead look for a different material which, similar to latex, is strong yet elastic but, unlike latex, can be glued to plastic. Latex is used for gloves because of it's strength and elasticity both of which are important properties for gloves to have. For this reason we decided to look at other materials which are also used to make gloves. Luckily, we found some boxes of nitrile gloves in the lab which we tested using many different types of glue and found adhered to plastic with the help of Loctite Plastic Bonder. After further testing of this material it proved to be effective for this project and we proceeded to order a thicker and more durable sheet of nitrile to make new prototypes with.
-Ian

Full Size Prototype

The prototypes I have been working on so far have not been large enough to fit a human leg.  It was easier to work with smaller prototypes and less materials were wasted in trying ideas that failed.  Now that we have some functional smaller prototypes I thought I was time to make som large full scale models.  I bought a pair of pants and used hot glue and foam to give them the appearance of an amputated leg.  I used the pants and a visual to help understand how big the prototype needs to be and then to test the prototypes once they are complete. 

 

Jean leg inserted inside the full scale prototype

 

The full scale prototype without the leg inserted

 

This is a picture from the making of the prototype.  To make the double shell design, I cut out this shape from the the plastic bag.  I seal the edges and fold it in on itself.  This makes an easy open zipper at the bottom for easily filling and emptying the bag and makes the entire prototype a continuous piece.

-Annie

Going Back A Few Steps...

As Annie’s intern she gave me the opportunity to work with the original “AspiraMolde”. It all started with the Silicone which was probably the most tedious part of the project because, a lot of it was gluing pieces of silicone together and then waiting for it to dry. Then, the next step was taking the now cylindrical silicone and screwing/gluing it to the lid of the bucket. Annie had done this once (see FRIDAY, JUNE 15, 2012 The Lid) it wasn’t too hard. It required some strength and patience(what most of the project required). Next, I moved to the inside of the bucket. The vacuum pump was still attached to the bottom of the bucket. All I had to do was attach a nebulizer to the top of a baby bottle( to act as a hose), attach a plastic bag (to hold the coffee), and then wrap the end of the plastic bag around the bucket to keep it airtight and in place. Simple, huh?Once everything was in place and assembled we poured the coffee grinds into the plastic bag, put the lid on, and turned on the vacuum pump.

It wasn’t perfect,not at all a final prototype (wrinkles showed in the silicone and it wasn’t as solid as we wanted), but it represented the concept of what we wanted. We were able to see what it looked like and if Annie should continued with the approach. Was the concept valid?

As a highschool student it taught me a lot. Patience and how to never give giving into being discouraged, To always try again and again, and a bunch more.

-Caitlin

What is AspiraMolde??

So I realized that it might be unclear what AspiraMolde is trying to accomplish.   AspiraMolde is a step in creating the socket which the prosthetic device will be connected to.  The socket is made from melting the plastic around a positive mold of the amputated leg, the stump.  A positive mold is made from the negative mold.  The AspiraMolde is a device that makes the negative mold using vacuum casting.

-Annie

latex prototype

Because of the wrinkles, I am trying to use latex to make the inner shell.  Latex is stretchy and should form better to the amputee's leg.  The weather balloon provided one source of latex.  Using contact cement, I connected the balloon to the outer plastic shell and made the full shape.  The weather balloon functioned well when attached to a vacuum with a bottle inside.

 

The weather balloon as the inner shell surrounded by coffee grounds

-Annie

Baby Bottles

I want the attachment between the vacuum and the shell to be easily to come apart.  The way I thought to do this was with threaded pieces.  I have used coke bottles and nebulizers to do it so far but I wanted to look into other options.  Coke bottles are more available than nebulizers, but nebulizers work better.  My new solution is baby bottles.  The baby bottles worked fairly well but didn't attach well with my vacuum hose.

 

The baby bottle next to an assembled attachment

 

 The unassembled attachment

-Annie

Weather Balloon

So the latex 646Q balloons didn't work as well as I had hoped for a flexible inner shell, but the latex seemed to be heading the right direction.  To create the shell I tried a weather balloon.  It's huge and flexible.  The challenge is to glue latex to itself and the plastic components. To connect the balloon I used contact adhesive.  

 

The balloon leg shell

-Annie

Plastic Wrinkles

The plastic bag has wrinkles when the vacuum is applied.  This will cause error in the mold and maybe create a mold that is unusable.  It the wrinkles are extreme, the socket made from the mold will not fit to the individuals leg.  To stop this problem a stretchy material may be used.  I started working with large latex balloons, but though they were the correct size inflated they started very small. 

 

inflated balloons are the right size 

 

the deflated balloons are too small to put a leg into

-Annie

Working on Aesthetics

To increase the durability of the AspiraMolde's outer shell, I am using fabric patches to cover it.  The nylon patches have adhesive on the back that does not need to be heated (not iron-on) but this limits the size.  The largest patches are 8"*8", so there are a lot of edges.  I have been trying to work on a method to keep the edges from peeling up while being flexible, I don't want it to fall apart.  I've tried Plasti-dip, epoxy and bathroom caulk to seal the edges.

 

On the left: plasti-dip covering the edges

On the right: edges with out plasti-dip

 

  

Epoxy covering the edges

The plasti-dip worked well and kept the bag very flexible.  The epoxy was better at holding the gaped pieces of nylon patch, but it was stiffer and cracked when bent.

-Annie

Hot Wax

I melted the wax down and poured it into the prototyped AspiraMolde.  The problem was that I didn't wait long enough for the wax to cool off before I poured it into the opening.  The plastic bag couldn't stand the heat and the seal gave way and the wax was sucked into the vacuum.  Because of the damage caused by the wax I had to modify the bag.  I still wanted to see if the bag could if withstand heat of the wax while it was cooler.  I cut the end of the inner shell out and sealed it back together smaller. Then, put the coke bottle back in the prototype and applied the vacuum.  It hardened and I poured the cooler wax in.  This time it didn't hurt the plastic, but the vacuum disconnected. The coffee and shell lost its hardness briefly  briefly before the vacuum was turned back on.  The finished shape doesn't really look like the coke bottle because of this deformity.  The wax did solidify though and I was able to remove from the bag once the vacuum was turned off.

 

Wax being removed from the bag

 

-Annie

Wax Positive Mold

To test my prototype, I wanted to make a positive mold from the negative and see the similarity in shape.  I got paraffin wax and a large pot to melt it in and today I melted some of the wax.

 

Paraffin melting inside the pot

 

large blocks of paraffin and the pot on a heater

-Annie

video of current prototype

This is a video of the vacuum casting prototype where a bottle has been inserted, vacuum turned on and the bottle removed but the coffee still maintains its shape.

One Way Valve Issues

I have been using a vacuum to creating the jamming effect in the modified vacuum bags.  The problem is that the vacuum that is strong enough to pull air out is also strong enough to lift the value up so that the coffee can also be pulled out.  This is a problem because the casting system slowly deteriorates and the vacuum will not maintain the shape of the coffee if the coffee is gone.  I have modified a value with a cloth covering.

 This is the inside of the testing vacuum, obviously the 1 way value has let coffee through

 This is the front of the value with the cloth backing

this is the back of the value

Also, the plastic isn't very strong or tear resistant.  I got nylon patches (so they just stick, with no heat) and have started to cover the shells with them.

 This is a sheet of the nylon patch

 nylon patches covering the delicate plastic shell

-Annie