8. Soft robotics¶
Research¶
The history of soft robotics traces back to 1950 with the invention of the McKibben artificial muscle, a pneumatic actuator originally developed for use in orthotics. This early innovation laid the foundation for the field, which began to grow significantly in the 1960s. Advances in materials science and rapid prototyping techniques later accelerated progress, allowing researchers to design robots that could safely and effectively interact with humans and adapt to unstructured environments. Throughout the 21st century, breakthroughs in compliant actuators and flexible sensors have driven the transition of soft robotics from academic research to practical, industrial, and biomedical applications—marking a major evolution in how robots move, sense, and engage with the world.
References & Inspiration¶
I have been deeply inspired by the Aeromorph Origami project from MIT’s Soft Robotics Lab, which beautifully merges engineering, design, and creativity. The idea of transforming flat sheets into three-dimensional, functional structures through pneumatic origami demonstrates how elegant and versatile soft robotics can be. What fascinates me most is how the project combines artistic inspiration from origami with cutting-edge material science and fabrication techniques to create systems that can move, fold, and change shape autonomously.
Tools & Materials¶
- Arduino UNO
- Arduino IDE
- Heat transfer vinyl
- Parchment paper
- Scissors, ruler, pencil and eraser
- Iron
- Silicone rubber tubbing 5mm
- Heat shrink tubbing 5mm
- Silicone P-53 polyformas 80 gr
- Catalyst 78 drops.
- Transistor MOSFET E13009
- N4007 Diode.
- 3V electric air pump.
- Wires and aligator clips.
Process and workflow¶
I built two inflatable soft robots—starting with a simple leaf design, then creating a more complex rabbit—developing both using the techniques documented by Adriana Cabrera. Additionally, I did a silicon soft robot from a 3D printed mold.
Inflatables¶
Step 1¶
I began by hand-drawing the leaf and rabbit designs onto heat transfer vinyl, then replicated the same shapes on parchment paper. I cut small rhombus-shaped openings in the parchment paper to allow air to flow through the structure.
Step 2¶
Using an iron, I fused the three layers together, placing the parchment paper in the middle and leaving space for the heat-shrink tubing. I sealed the tubing with a lighter and then attached a rubber tube to enable inflation.
Step 3¶
I first inflated both the rabbit and the leaf manually using a hand pump. Later, I built a circuit with an Arduino to control an air pump, allowing the soft robots to inflate automatically.
My hand drawn rabbit sketch and the circuit to control the air pump
Circuit¶
Arduino Code to control the air pump¶
const int pumpPin = 9;
void setup() {
pinMode(pumpPin, OUTPUT);
}
void loop() {
digitalWrite(pumpPin, HIGH);
delay(5000);
digitalWrite(pumpPin, LOW);
delay(12000);
}
Silicone soft robot¶
I built a soft robot inspired by the four-leg gripper developed by the Whitesides Group at Harvard University.
Step 1¶
I downloaded the four_leg_gripper.stl file from the Instructables website and 3D printed the mold.
Step 2¶
I prepared the silicone mixture by combining 80 g of silicone with 78 drops of catalyst. After mixing thoroughly, I poured the mixture into the 3D-printed mold. I also poured an additional portion onto a tray to create the robot’s second (top) layer.
Step 3¶
Once the silicone solidified, I carefully unmolded the soft robot. I then prepared a fresh silicone mixture and spread a thin even layer on the tray to serve as an adhesive for bonding the top and bottom halves of the robot together.
Step 4¶
After curing, I removed the assembled robot from the tray and trimmed any excess material.
Step 5¶
Finally, I created an inlet for a rubber tube, connected it, and inflated the robot using an Arduino-controlled pneumatic system.
The air pump circuit and the gripper.
Results¶
Learning Outcome and Observations¶
When making inflatables, it is important not to overheat the vinyl sheet, as excessive heat can burn the material and prevent it from functioning properly.
I found it challenging to insert the heat tube. During my first attempt, I left too narrow a space for insertion; on the second try, I accidentally sealed the entrance. Finally, I had to secure it with tape because the air was leaking.
In my experience with the silicone soft robot, inserting the tube also required caution — it’s important not to cut too deeply. Despite being careful, some air still escaped, so I sealed the area with additional silicone mixture. Furthermore, the robot should not be too rigid, as it needs some flexibility to inflate correctly.
Fabrication files¶
Videos¶
From Vimeo¶
Soft robot leaf control by Arduino
Pouring silicone for the soft robot
Four leg gripper --- --- --- ---