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8. Soft robotics

Research

This week we are looking into soft robotics. This is a new topic for me, I have not heard of this before and I don't have any relevant experience however, it seems very interesting. I started by looking more into the concepts and applications.

Soft robotics Is a multidicisplinary field that brings together biology, math, physics, mechanical engineering, software engineering. They are usually inspired by nature, specifically by ocean life which can solve complex problems and move in a way that is different to regular robotics which have hard components that move in a very calculated and predictable way.They're supplementary to hard robots so we should look for use cases that require the soft component, the flexibility of the material and the specific motion that soft robotics allow.

Advantages:

  • Resistance to damage: they don’t break since they are soft and the materials sometimes can absorb impact.
  • Light weight
  • Lower costs
  • Properties of materials can replace controls
  • New opportunities in motion or mechanics

Industries:

  • Biomedicine
  • Agricultural: food picking, sorting
  • Fashion/Textile
  • Hazardous tasks/search and rescues

In fashion we have seen applications such as the Schiaparelli beating heart necklace for Fall 2025 Couture, an anatomically shaped beating heart covered in rubies.

This launch was a bit controversial in Mexico because designer Grecia Soto did it in 2024.

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References & Inspiration

Soft robotics take a lot of inspiration from ocean animals in they form, movement and even materials. Both jellyfish and octupuses use jet propulsion to move around this translates to using multi-chamber inflatable arms in soft robots.

via GIPHY

via GIPHY

via GIPHY

via GIPHY

Tools

Process and workflow

Previous years tests

Silicon Soft Robot with airpump

Soft Muscle

Credit: Louise Massacrier

Creating our own silicone soft robots

Depending on the type of silicone, you have a recipe. We decided to go with EcoFlex 00-30 to do 4 samples: X shape, star + blue pigment and triangle (with mesh fabric inside), circle.

* 100g silicone
* 5g catalyst
* .5g of blue pigment

* pots
* stove
* spatula
* scale
* molds

* Measure the part A and B (silicone and catalyst)
* Add the pigment and mix well
* Spray the antistick solution into the molds
* Pour the mix into the molds and let dry for 4 hours, ideally 24h.
* Use a flat surface/box to create the other silicone cover
* Use oven/dehydrator 65C for 15min (adriana recipe)
* Unmold
* put the 2 pieces together and add more silicone on the sides to seal and create the air chamber

Results: We had some issues with the curing of the silicone of the molds. One of them didn't cure at all, 2 of them ripped and even after trying to repair them, the results (as shown below) were not the best. My take away here would be to use a generous amount of silicone when fusing the 2 sides to prevent holes rather than trying to repair them later.

X mold results:

This one had a rupture I tried to fix by adding a layer of silicone on top however, it was thinner than the rest of the mold which caused air to flow to the path of least resistance. This thin layer created a bubble when using the airpump.

Round mold + Felted Wool results:

With the help of Capucine, I learned how to felt wool in a specific shape. We tried to make a wool "cover" for the silicone mold. I did not get to try it because the silicone ruptured. I managed to record a small video (above) where the 2 pieces of silicone were already letting air out.

Thermoadhesive Vinyl

I started by replicating Adriana Cabrera's tutorials to see how the mechanics would behave.

  • Start by cutting the shapes in parchment paper
  • Make a sandwich with the termoadhesive vinyl and use an iron or heat press to seal the vinyl.
  • The parchment paper will prevent the vinyl from sealing, therefore creating an air chamber.
  • Use a zip tie to hold in place the plastic tube to inflate

!

I was inspired by the movement of the scorpion tails to create my own design. Scorpions are known as alacranes in México, and are common in the area I live in (northern part of México).

via GIPHY

I read Saskia's UNFLATABLES documentation to understand which shapes would get me the curl results I wanted then adapted the rest of the shape to resemble a scorpion tail.

  • I added the rhomboid shapes at the en of each section of the tail and cut them in baking paper.
  • Then, I cut 2 pieces of thermoadhesive vynil in the shape of the tail, making sure that they were bigger than the parchement paper cutouts.
  • Used an iron to sandwich the paper in between the 2 layers of vynil.
  • An air bubble formed in the first air chamber, creating a bubble which prevented the air flow to go to the tip of the tail. I believe the curl motion was achieved but could have been better if it weren't for the bubble.

Arduino Code & Connections

Credit: Louise - Le Textile Lab

int motor = 3;

// the setup function runs once when you press reset or power the board
void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(motor, OUTPUT);
}

// the loop function runs over and over again forever
void loop() {
  digitalWrite(motor, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);                       // wait for a second
  digitalWrite(motor, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);                       // wait for a second
}