Fabrication

This section will discuss what is needed and how to build both Pneumatic Deformation Sensors. The following page has a bill of materials for sensor designs 1 and 2 and both breadboard and soldered versions of the circuit. The pages after that has step-by-step instructions for building all of the previously mentioned things.

The instructions for the circuits will require knowledge of reading a circuit diagrams and soldering skills. Tutorials for said things can be found here and here.

Bill of Materials

Design 1 Bill of Materials

Materials:

NameQuantityPictureLinkNotes
Ecoflex 00-30 Silicone1Via Amazon 
Zip-Tie1Via Amazon 
1/8" Tubingat least 2"Via Amazon 
1/4" Tubingat least 1"Via Amazon 
Filamentat least 350gVia AdafruitWill depend on your printer
Luer Fitting1Via Cole Parmer 

Tools:

NameNotes
3D PrinterMust have a z-axis of at least 100mm
Clamps 
Cup 
Spoon 
Scoop 
Screwdriver 
Flush Snips 

Design 2 Bill of Materials

Materials:

NameQuantityPictureLinkNotes
Ecoflex 00-30 Silicone1Via Amazon 
Zip-Tie2Via Amazon 
Filamentat least 150gVia AdafruitWill depend on your printer
1/8" Tubing2 lengths of at least 3"Via Amazon 
Luer Fitting1Via Cole Parmer 

Tools:

NameNotes
3D PrinterMust have a z-axis of at least 100mm
Clamp 
Cup 
Spoon 
Scoop 
Flush Snips 
SyringeAn air compressor or squeeze bulb could be used too

 

Electronics (Breadboard)

Materials:

NameQuantityPictureLinkNotes
Arduino Uno1Via AdafruitAn Arduino Leonardo could also be used here
Half-Sized Breadboard1Via Adafruit 
10KΩ Resistor3Via Adafruit 
2.7KΩ Resistor2Via Amazon 
1KΩ Resistor1Via Amazon 
0.1uF Capacitor2Via Amazon 
10uF 50v Electrolytic Capacitor2Via Amazon 
LM358 Dual Op-Amp1Via SparkFunAny of the LM358-series chips will work
MPS20N0040D-D Pressure Sensor1Via Amazon 
Male-to-Male Jumper Wires10Via Adafruit 

 

 

Materials:Electronics (Soldered)

NameQuantityPictureLinkNotes
Arduino Micro1Via Adafruit 
Half-sized Perma-Proto Board1Via Adafruit 
10KΩ Resistor3Via Adafruit 
2.7KΩ Resistor2Via Amazon 
1KΩ Resistor1Via Amazon 
0.1uF Capacitor2Via Amazon 
10uF 50v Electrolytic Capacitor2Via Amazon 
LM358 Dual Op-Amp1Via SparkFunAny of the LM358-series chips will work
MPS20N0040D-D Pressure Sensor1Via Amazon 
22AWG Solid-Core Wireat least 10"Via Adafruit 
DIP-8 IC Socket1Via Amazon 
Female Headers1Via Adafruit 
Solder1Via Adafruit 

Tools:

NameNotes
Flush Snips 
Wire Strippers 
Soldering Iron 
PCB ViceOptional, but will come in handy when soldering

Design 1 Fabrication

This page will go over the steps to create Design 1 of the PDS.

Step 1:

Begin by printing the .STLs for three-part mold that are found on the Downloads page. Print 1x design1_core.STL and 2x design1_outer.STL. Supports are not necessary for printing.

Step 2:

Assemble the mold with the two outer pieces surrounding the inner core. Put the two clamps around the mold.

Step 3:

Measure out 25ml of Part A and Part B of the Ecoflex 00-30. Put both parts in a cup and mix together thoroughly with a spoon.

Step 4:

Pour the mixed Ecoflex into the mold slowly and steadily and stop occasionally to let bubbles escape. Fill the mold to the brim. Let the silicone cure for 4 hours.

Step 5:

Once the Ecoflex has cured, take the clamps off of the mold and use a screwdriver to pry apart the mold. Pull the cast off of the core.

Step 6:

Attach the lengths of 1/4" and 1/8" tubing with the luer fitting.

Step 7:

Insert the 1/4" end of the tube into the open end of the silicone cast. Secure a zip-around around it and tighten it into place, securing the tubing.

Step 8:

Connect the 1/8" end of the tube to the pressure sensor on the electronics.

Instructions on how to operate Design 1 can be found in the Testing section.

Design 2 Fabrication

This page will go over the steps to create Design 2 of the PDS.

Step 1:

Begin by printing the .STL of the mold found on the Downloads page. Supports are not necessary for the print.

Step 2:

Measure out 25ml of Part A and Part B of the Ecoflex 00-30. Put both parts in a cup and mix together thoroughly with a spoon.

Step 3:

Pour the mixed Ecoflex into the mold slowly and steadily and stop occasionally to let bubbles escape. Fill the mold to the brim. Let the silicone cure for 4 hours.

Step 4:

Once the Ecoflex has cured, carefully pull the cast out of the mold. Wiggling the cast back and forth helps to remove it.

Step 5:

Follow the Fabrication guide for the PneuNets Bending Actuator up to "Remove main body from molds" in Step 3.

Step 6:

Mix a very small amount of more Ecoflex. Spread a very thin layer (1mm) of it on the flat side of the PDS. Place the cast of the actuator on top of it carefully. Let the silicone cure for 4 hours.

Step 7:

Connect one length of the 1/8" tubing to the Luer fitting. Puncture the end of actuator that is at the same end as the opening of the sensor with a screwdriver. Insert the end of the Luer fitting into the hole. Put one zip-tie around this part of the actuator and the sensor and tighten it only slightly, so that it is held in place. Insert the other length of tubing into the opening of the sensor. Put a zip-tie around this part and tighten.

Step 8:

Connect the tubing from the actuator to the air source (syringe, air compressor, squeeze bulb) and connect the tubing from the sensor to the electronics.

 

Instructions on how to operate Design 2 can be found in the Testing section.

Electronics Fabrication

This page will go over the steps to create the breadboard and the soldered versions of the electronics.

Breadboard

To build the electronics on a breadboard, follow the breadboard diagram and circuit schematic below.

 

Soldered

To build the electronics on a soldered Perma-Proto board, follow the breadboard diagram (Perma-Proto boards and breadboards have the same layout) and the circuit schematic.

Remember that the Arduino and the LM358 IC are not soldered directly in. Female headers and DIP sockets are soldered in instead.