Soft robotics

Make a mold

The mold to make a softrobot consists of two parts, one part is the one that has the air channels and the other part is the one that closes the open part of the channel. The model is laser cut with 3mm thick acrylic, once cut the pieces are stuck between them, without leaving holes between the layers. TIP: The outer edge of the model must be higher than the central figure that you want to inflate. In this case the central figure is 3mm thick, and the edges have 6, so the upper layer of the soft robor will have a thickness of about 3mm in thickness.

Ecoflex 0030

There are many types of materials to develop this type of soft robot but in this case I have used the ecoflex 0030. The instructions are simple, mix 50% the two components part A and part B.

mix components

Once well mixed the two parts are spread over the molds in a homogenized manner.

Take out the air

The ecoflex 0030 tends to create many bubbles that make the soft robot can cause it to break or have small open holes. Therefore it is advisable to use a vacuum pump to remove all the busbujas.

Curate in the oven

Curing the ecoflex in the oven accelerates the curing process a lot, with an average time of 15 minutes being cured at a temperature of 150F.

Assamble parts

To make the soft robot more resistant to the part A of the mold you can add a piece of cloth before on the ecoflex before curing it in the oven. To join the two parts a thin layer of ecoflex between the two layers is put and put back into the oven. If the material between the two layers is excessive, it is possible that the channels are obstructed by the excess of ecoflex.


The first test to inflate it has been interesting. The idea was for the three spheres to perform at the same time, but in this case they swell progressively. This is due to the difference in material between the spheres. When putting the ecoflex in the oven it was slightly inclined, which caused the back to have a thicker layer than the previous one. The thinner the layer is, the easier and bigger it becomes.


With this mold perform a ferrofluid test. To know if you could control the ferrofluid between the spheres, fill the inside of the channels with water and iron dust. Unfortunately ferrofludo does not pass as easily through the channels as expected.

Mold 2

This pattern is designed to create a texture of inflatable bubbles. again use 3mm acrylic cut in the laser, and then pasted.


Fortunately the ecoflex did not stick to the model and I was able to get the first result satisfactorily


Once the two parts of the mold are joined and dried, the soft robot is swollen, as you can see this time the spheres are swollen evenly. There has only been one failure with one of the channels that has been obstructed by pasting both parts.


The soft robot adheres to the wrist when inflating the channels, making it like a grip. I love the aesthetics obtained and the texture, reminding me of pearls and bubbles.

Mold 3

Design that mold specifically for fluids, so the channels have an entrance and an exit. By reducing the size of the channels, the binding ecoflex between the layers obstructed the external channels.


The yellow channel was obstructed so I could only see the results of the red channel, by injecting the water with red dye.

  • Arduino + solenoide + motor
        int solenoidPin = 4;    //This is the output pin on the Arduino we are using
    void setup() {
      // put your setup code here, to run once:
      pinMode(solenoidPin, OUTPUT);           //Sets the pin as an output
    void loop() {
      // put your main code here, to run repeatedly:  
      digitalWrite(solenoidPin, HIGH);    //Switch Solenoid ON
      delay(2000);                      //Wait 1 Second
      digitalWrite(solenoidPin, LOW);     //Switch Solenoid OFF
      delay(2000);                      //Wait 1 Second