Introduction: Inch Worm Soft Robot

(Time-lapsed videos above of Inch Worm Soft Robot)

A few months back, I saw the videos of Matthew Borgatti’s soft robots (videos below) and was really captivated by them. They inspired me to think about building a soft robot using pneumatic pressure for locomotion, but as a newbie to both Arduino and silicone casting, I decided to make a simplified version using more off-the-shelf, readily-available materials. This inch worm soft robot uses a party balloon, a hacked blood pressure monitor (for the pump, psi sensor, etc.) and some sheet silicone and vinyl. And an Arduino starter kit, of course! This robot is still connected to the Arduino UNO (and connected back to a laptop), but I eventually will miniaturize it and transfer it to a Pro-trinket and house it within the robot. Also, I am hoping to be able to add a more powerful pump to get the worm to move faster... the videos you see are time-lapsed (10x faster). Updates on this to follow!


Basic Arduino

Basic soldering

Basic sewing

Moderate-level craftiness (to assemble pieces)


1 blood pressure monitor (arm type)

1 balloon

1 sheet of vinyl (11” x 17”)

1 sheet of silicone (11" x 17")

1 sheet of aluminum 1/16” thick (8”x11”)

solid core electrical wires

rescue tape

double-faced tape (carpet type is stronger)


soldering gun

hot glue gun

sewing machine

laptop/Arduino software

small screwdriver

When you are ready to miniaturize transfer things over to a smaller microcontroller, you will need:

1 Adafruit ProTrinket - 5V 16MHz

1 Adafruit Lithium Ion Battery - 3.7v 2000mAh

1 Adafruit Power Boost 500

Step 1:

Step 2: Hacking the Blood Pressure Monitor

First step is to hack the parts from the blood pressure monitor so open it up by removing all the screws.

Pull apart the plastic pieces; be careful not to damage the internal components.

Gently pull the parts out of the plastic housing.

Cut the fabric away on the arm sleeve. Inside will be a plastic shell and air bladder.

Step 3:

Step 4: Labelled Parts

What is inside:

1. Microcontroller board

2. Display screen

3. Pump

4. Bleeder valve

5. Rigid plastic bladder

6. Soft PE bladder

7. Tubing

8. Battery pack

9. Recharging port

10. Small transformer

The display screen, recharging port and small transformer will not get used. These parts will get removed.

Step 5: Hack the Arm Band

Now take apart the arm band. Snip off the surrounding fabric.

To pull out the plastic cuff, disconnect the grey tube from the soft bladder. Do this by pulling off the grey tube and backing out the connector from the bladder.

Reconnect the grey tube to the connector after the cuff is removed.

Step 6: Cut Down the Plastic Casing

Use a hack saw to cut down the plastic casing to make the battery pack smaller.

Step 7: Extending Electrical Wiring & Tubing

The electrical wiring is quite short and will need to be made longer for the inchworm. (Solder off the short ones, and solder on new longer wires—about 8”-10”.)

The rubber tubing is also a bit short for this project, so extend with longer ones (8" - 10").

Step 8: Remove Transformer

Solder off the connections to the transformer-- this will not be needed.

You will also cut off the display screen.

Step 9: Assembling the Housing

Use silicone and vinyl sheets to create the exterior or housing of the worm.

Cut out 5-1/2" wide x 13-1/2” sheet from the vinyl.

Cut a 5-1/2”w x 20” long sheet of the soft silicone. This will get sewn on top of the acrylic sheet to create the segments of the inchworm.

The hard vinyl will form the bottom and the soft silicone will be the top.

The segments are 2"wide on the bottom, the silicone on top is 3-3/8"wide.

Create each segment one at a time. Measure each out, tape down with masking tape to hold in place to sew together.

Step 10: Create Hole for Air Tube

Drill a hole in the sheet vinyl for the air tube (the one you removed from the arm band) at the center of the sheet vinyl. Plug in the plastic connector for the air tube. The balloon will get connected to this later.

Step 11: Finish Sewing Segments

Finish sewing the segments.

The parts from the heart rate monitor and the miniaturized Arduino (Adafruit ProTrinket) will get housed inside each of the segments.

Step 12: Create Holes for Tubes & Wires

Drill some additional holes along the underside of the vinyl. These will be used to chase through various air tubes and electrical wires.

Step 13: Create the Air Bellows

Use Dixie cups to create an air bellows to contain the balloon that will be attached to the air tube.

Cut the cups down to 1-1/4" slivers so they stack one inside the other. Spray paint if you lilke.

Cut out a circular piece of vinyl to create the top of the bellows. Make an x-slit at the center for the balloon to pass through.

Slide the top on to the air tube through the slit.

Attach the balloon to the air tube using rescue tape.

Tape the top to the bellows.

Step 14: Cosmetic Touches

Insert some acrylic pieces into each segment to keep the form rounded.

Thread through some neon rubber tubing to give it an undersea water creature effect!

Step 15: Arduino Code

Step 16: Wiring Diagram