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8. Soft robotics

Research & Understanding

Basic concepts

New week, new topic that I had never explored before. This class focused on Soft Robotics, a special field of robotics inspired by nature and living organisms. Unlike traditional rigid robots made of metal and hard joints, soft robots are built from flexible and elastic materials that can bend, stretch, and move more like a living body.

Soft actuators, sensors and grippers are the components that enable movement and interaction. During this week, we created them using silicone, fabrics, and other flexible materials to explore how movement (locomotion), airflow, and material structure can generate motion.

  • Soft actuators (muscles): enable the robot to bend, twist, or expand through the use of air or liquids.
  • Soft sensors (skin): detect touch, pressure or movement and provide feedback to the system.
  • Soft grippers (hands): made of soft materials that can safely hold and manipulate delicate objects.

Textiles and Soft Robotics

While approaching this topic, I was curious about fabrics application.
In soft robotics, textiles can act as actuators or sensors: conductive polymers integrated into woven or knitted fabrics create threads that deform with electrical stimulation. Woven structures amplify force, while knits enhance flexibility, turning simple textiles into active components. Natural fibers like wool add elasticity, making them ideal for flexible designs that merge traditional techniques (knitting, weaving, felting) with advanced technology.

Weekly assignment

  • Document the concept, sketches, references (also to artistic and scientific articles)

  • Make a soft robotic sample, develop the pattern for the Inflatable and draw a sketch of the air flow (A pneumatic wrist brace (basic level) - a Soft Gripper (intermediate level) or build and document a Pneumatic, digitally controlled system, electronics schematic, electronic control and code (advanced level) )

  • Experiment with different materials (silicone, 3d printing, parchment paper, thermoadesive vynil, TPU fabrics, bioplastic)

  • Make a small video of your inflatable/soft robot working AND Upload your digital design files

  • Build the electronic circuit to control your inflatable/soft robot (extra credit)

References & Inspiration

Fabricademy Alumni

  • In her page, Alessia Pasquini from TextileLab Amsterdam clearly explained how to conduct tests with vinyl and I really liked the motifs she drew.

vinile Credit: Alessia Pasquini

  • In “UNFLATABLES”, Saskia Helinska explores soft‑robotic inflatables in wearables and e‑textiles. Her project investigates material‑driven inflatable actuators for visual and haptic feedback. The outcomes show how touch‑based interaction requires different design strategies than visual deformation.

saskia Screenshot from Dr. Lily Chambers and Adriana Cabrera lecture

Nuragic Sardinian symbols

  • The Pintadera: an ancient terracotta tool used during the Nuragic era to decorate and “brand” bread. With these molds, bread and focaccia, which at the time were also used as a form of exchange, were imprinted with distinctive patterns, functioning like archaic stamps. A Sardinian bank later adopted the pintadera as its symbol and it is also used today as a decorative motif for silver jewellery.

  • The ‘Dea Madre di Porto Ferro’: discovered near Alghero, this figurine depicts a standing nude female with a circular head, long slender neck,triangular nose, trapezoidal torso and conical breasts. It is an icon of Sardinian prehistory, associated with fertility and feminine symbolism. The original was carved in stone during the Neolithic era, but today the figure is often reinterpreted in silver jewellery, as in my reference piece.

nuragic Credits to Pinterest: 1 & 2

Results

The outcomes will be included in Week 9, as it was not possible to complete them during this week’s session.

Process and workflow

For personal reasons, I was able to work in the lab for only two days during the assigned week, so some of the final results are still missing from this page. I’ll update it once I’m back in Lyon and have completed all the assignments.

Inflatable actuators: baking paper and thermo vinyl

To create them, I used only two materials: baking paper and thermo vinyl, plus a pump to inflate (or just my breath). I followed this tutorial by Adriana Cabrera and used her slides as a reference for the building process.

baking Credit to Adriana Cabrera

Process I followed:

  1. Draw a design on baking paper. The drawn part is the one that will inflate.
  2. Cut two equal, slightly larger pieces of vinyl to enclose the design.
  3. Place the baking paper with your design between the two vinyl sheets, making sure the shiny sides face outward. Remember to include a channel to blow air.*
  4. Use an iron or a heat press to seal the three layers together.
  5. Once cooled, peel off the protective film.
  6. Insert the pump in the channel and inflate your element.

I decided to reproduce the two Sardinian elements shown in the References & Inspiration.

disegno

After cutting the two vinyl pieces and attempting to stick them together, I realized they were not the heat-sensitive type and therefore not suitable for the experiment. I will need to complete the exercise once I return in the lab, as the heat-sensitive vinyl was not available during the two days I was there.

vinile

Casting: silicone and molds

Diana and I explored the creation of soft actuators using silicone casting. These flexible components can bend, twist or expand when inflated with air, forming the basic building blocks of soft robotic systems. By adjusting the mold design, for example adding finger-like shapes or textured surfaces, these actuators can also function as soft grippers, though they may require a stronger air pump or higher pressure to achieve sufficient force.

We experimented using 3D-printed molds already available in the lab and followed Adriana Cabrera's tutorial to prepare our silicone recipe and fill the molds.

Each configuration is composed of two mold halves which are then joined together to create the soft element. As secondary molds, we used embroidery hoops, which we filled completely and then cut to obtain a second piece similar to the first one.

The main part of the recipe is the silicone. Each silicone product is a dual-component system: Component A (base) + Component B (catalyst/curing agent), typically mixed with a 50:50 ratio but refer to the product’s technical sheet.

In our lab we have three types of silicone and chose the third one for its easy mixing and fast drying properties:

Important: do not mix silicones from different brands, as incompatibilities may prevent proper curing.

silicone

We used three molds, following these configurations:
1. Standard recipe
2. Recipe + colored pigment
3. Recipe + piece of textile (mesh): designed to alter the shape and behavior of the actuator, simulating the movement of a simple gripper.

molds

Silicone molds preparation

Ingredients:
* Silicone (Ecoflex 00-30 in our case) * Anti-Stick spray (e.g. CoolSlip) * Pigments (optional) * A piece of mesh fabric (optional)

Tools:
* A precision balance * A spatula or mixting stick * 3D molds * Mixing/dosing containers * Gloves (we forgot to use them, but luckily the silicone we used was harmless)

Silicone mold recipe:
1. Weigh 50 g of Part A and 50 g of Part B of your silicone. Then mix them gently until the color and texture are uniform. Avoid introducing air bubbles. 

2. Spray the anti-stick spray inside the mold to prevent adhesion and facilitate demolding. <br>

3. Pour the mixture into your molds, remove bubbles with a mixting stick. <br>

4. Let the silicone cure according to the product instructions. To speed up drying, you can use an oven or a dehydrator set at a low temperature (around 40–50 °C), making sure not to overheat. <br>

5. Adding pigments (optional): If you want to color the silicone, mix up to 2 % pigment (relative to the total weight of A + B). Add the pigment first to one component (e.g., Part A), mix well, then add Part B and mix gently. <br>

6. Adding fabric (optional): use your smooth mold (like the closing part), pour a first thin layer of silicone into the mold. Place the fabric on top and cover it with a second layer of silicone. The embedded fabric enhances flexibility and control over the silicone’s movement and behavior. <br>

//add video

Note: even after waiting more than 4 hours and using a dehydrator, the molds took some days to fully cure. In some cases, they were still not ready — for example, the one containing a mesh.

Controlling the components with Arduino UNO

The idea for this part, it was to inflate the components created above usign an air pump connected to Arduino. We replicated the configuration developed by Louise Massacrier at Le Textile Lab, using a circuit created during Wearable Week.

The circuit included:
- a transistor: acts as an electronic switch between the Arduino and the air pump. When the Arduino sends a signal, it allows current to flow and powers the pump.
- a resistor: placed at the base to limit the current into the transistor.
- a diode: added across the pump to protect the circuit from any reverse voltage spikes caused by the motor’s inductance.

circuit Credit to Louise Massacrier

test

Configuration tested in the lab

Arduino code

/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(3000);                       // wait for a second
  digitalWrite(motor, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);                       // wait for a second
}

With Capucine, I ran a first test using elements already available in the lab, while waiting for the molds that Diana and I created to dry. Once the Arduino code was running and the circuit connected, the pump made a small noise and inflated the element.


Test with our molds. Unfortunately they did not worked as expected.

Credit to Diana Castillo

What's Next: more to explore

Laser Welding with TPU: I’m intrigued by the tactile quality and flexibility of this approach, as seen in Alessia Pasquini’s work above. The material wasn’t available in the lab and, since it is plastic, I would prefer to explore more natural alternatives.

Bio-silicone: a simple gelatin-based (animal) recipe is available on the Fabricademy network, but I’m more interested in developing plant-based alternatives. I plan to experiment with alginate mixtures, inspired by Isobel Leonard’s work.

Wool application: I was interested in exploring ways to apply wool to the experiments. Capucine suggested creating a 3D felted shape that could follow the form of the soft actuator and act as a decorative outer cushion. This activity was scheduled for Friday, when I wasn’t in the lab, but I look forward to exploring it further.

Credit to Diana Castillo

Tools

Images: Martina Muroni unless otherwise stated.