This project explores a variety of materials in order to create an interactive jellyfish diorama. The inspiration for this project came from a material called Ecoflex which is a brand of "biodegradable super soft silicone", which is somewhat translucent when formed. It's soft rubbery look and feel also lends itself to creating sea creatures.
In order to create an interesting and interactive diorama we wanted to find a creature which had a variety of interesting behaviors we could recreate. Bioluminescent jellyfish seemed like the obvious solution! You can read about lots of interesting bioluminescent creatures and their behaviors here.
To create the glow found in bioluminescent jellyfish we used black light tracer known as "T-900 Series Blue Aqueous Tracer" available here. To activate the tracer you need uv light, for this we used UV LEDs from DigiKey.
The other major part of this project was movement of the creature. This was accomplished with Flexinol brand muscle wire.
EcoFlex Soft Silicone
T-900 Series Blue Aqueous Tracer
Step 1: Mixing EcoFlex Silicone Rubber
EcoFlex Supersoft silicone rubber is a two part silicone. Different quantities can be ordered from here. the trial kit being sufficient for this project.
To create an item with this, the two parts are mixed in equal portions. Before measuring out the two portions, make sure to thoroughly mix each part. The silicone separates if not used for a while, and thoroughly mixing each part ensures best results. Make sure to use two separate stir sticks for this, otherwise the individual parts will be contaminated.
There are a variety of ways to measure the individual parts. For this project, a pair of large syringes were used. Small measuring cups also work well, but are better suited for mixing larger quantities.
The two parts are poured together into a mixing cup, and then thoroughly mixed using a stir stick. Make sure to stir such that the bottom, sides and corners of the mixing container are agitated, otherwise there will be some unmixed part of the silicone. This may affect the cure, and could cause part of the final product to simply be a sticky liquid, rather than a smooth form. Two minutes of mixing is usually sufficient.
Once mixed, let the silicone sit for a few minutes. Bubbles will form after mixing, though this isn't immediately obvious. Letting the silicone sit allows these bubbles to form and rise to the surface. If this part is ignored, then any product placed in a close form will have bubbles embedded in it. (The best option is to place the mixed silicone in a vacuum chamber, but this is probably outside most people's collection of tools).
Step 2: Creating Jellyfish Bell - Part I
The jellyfish bell will be created in stages. The initial stage is to have a silicone base to build upon. For this project, a pair of plastic bowls were used. The bowls should be sized in such a way that one fits inside the other with a consistent gap between the surfaces of the bowls. Ecoflex Supersoft 00-30 silicone was used to make this and the remaining parts of the jellyfish. This product is available here.
For this step, we used the following items:
1. Ecoflex Supersoft 00-30 silicone
2. Two bowls of slightly different diameter
3. Two 35 ml syringes
4. Disposable stir sticks and mixing cups
Prior to mixing and pouring the silicone, determine the amount needed. To do this, pour some water in the larger bowl, and press the smaller bowl inside, allowing any excess water to drain out. Once this step is finished, suck the remaining water into one of the syringes, noting how much volume there is. With our bowls, this needed to be done twice: the volume ended up being ~45 ml. Erring on the side of having too much, we mixed 50 ml of silicone.
Step 3: Working With SMA
Step 4: The First Movement
Step 5: Making It Blink and Glow
Step 6: Making and Attaching Tentacles
The final part of making the physical jellyfish is to make and attach tentacles to the bell of the jellyfish. Rather than making tentacles individually, a thin sheet of silicone is made, from which tentacles can be cut. The sheet can be made in any available container. Plastic packaging works well, as it is readily available in many sizes, and disposable.
Pour enough silicone to make a sheet about 1/16" thick. Once cured, peel the sheet from the form. Using an X-Acto knife, slice individual tentacles roughly 1/8" wide. Taper the cut so that it is a point at the tip of the tentacle.
Tentacles will be attached to the stiffening wire in the bell using 30 gauge wire. Thread a short piece of wire through the top of the top of each tentacle. Once finished, thread the wire around the ring, twist to secure and clip any excess. When finished, the jellyfish should look complete.
Step 7: User Interface
User interface is a critical component to a project such as this. One major purpose was to demonstrate to a viewer the purpose of the "burglar alarm" action. The atolla wyvillie jellyfish flashes the burglar alarm whenever it is attacked. The purpose of this is to attract larger predators to itself, so that the creature attacking it is attacked. Basically, it's considered a defense mechanism (or perhaps, a "jerk" mechanism, as the jellyfish is essentially causing one last problem for the animal eating it, rather than just being consumed gracefully like other invertebrates).
While a simple button could be employed to trigger the burglar alarm, this didn't convey the reason why this jellyfish has this behavior. Rather, we wanted the viewer to pretend to be the attacker. To do this, we opted to trigger the burglar alarm with a accelerometer embedded in a plush jellyfish. The viewer picks up the plush jellyfish, and can gently shake it, as if he or she was attacking it. In order to sense a shake, the 3 axes of the accelerometer are looked at individually for sudden changes in orientation. Our silicone jellyfish then responds appropriately by flashing the burglar alarm. This effectively converts interaction from passive observation (after pushing a button) to an active interaction. We feel this approach grabs the viewer's attention, and is a particularly good way to get small children interested in the piece.
The accelerometer can be attached to the arduino using simple wires. If available, a long ribbon cable works and looks much better.
A However, any plush jellyfish can be used as an input device. Simply cut open the seam, and push the accelerometer in. The L shape of the accelerometer and connector effectively wedges the device into the stuffing. The seam could be sewed shut; we opted to leave it open.