Interactive Smart Textile Moth That Communicates With an HP Otto Robot

I wanted to combine a long-planned plush sewing project by the designer Choly Knight with smart textiles and interactive electronics. The result is a soft moth plush that contains capacitive textile sensors, NeoPixel LEDs and a microcontroller.

When the moth is touched or shaken it lights up and plays sounds. It can also communicate wirelessly with an HP Otto robot via Bluetooth Low Energy. When triggered, the robot performs a short movement and sound sequence, and the moth reacts with lights and sounds.

Main features:

1. Capacitive touch sensors integrated into the wings
2. 4 NeoPixel LEDs attached to the wings
3. Shake detection with sound playback (The Circuit Playground Bluefruit contains a built-in accelerometer for motion detection)
4. Bluetooth communication with an HP Otto robot

Pattern Credit

The plush moth used in this project is based on sewing and embroidery patterns created by Choly Knight (Sew Desu Ne?). I am not the creator of these patterns.

For this project, I purchased the original patterns and modified the design to integrate electronics, sensors, and a battery pouch. The plush shown here is therefore a derivative work modified from the original pattern.

This tutorial only explains the electronic integration and the modifications I made. It does not include the original sewing pattern files, templates, or instructions. To recreate the plush you must purchase the original patterns from the designer.

This use follows the designer’s Terms of Use, which permit modifications of the design as long as the original creator is credited.

Original patterns by Choly Knight (Sew Desu Ne?):

Moth Plush Sewing Pattern

Bug Eyes Embroidery Design

1. Sewing and embroidery patterns listed above
2. Sewing thread (non-conductive)
3. Embroidery thread (non-conductive)
4. Stainless steel conductive sewing thread
5. RFID conductive fabric pieces
6. Polyester filling
7. Non-conductive fabrics as specified in the instructions (I used fleece and faux fur for the body and cotton for the wings and the battery pouch.)
8. 2 pipe cleaners
9. 14 Sew-on snap fasteners (5 mm)
10. 1 snap fastener for riveting
11. Iron-on volume fleece H250
12. Tear-away stabilizer (for embroidery)
13. Water-soluble film (for embroidery)
14. Ink pad (contrasting color to the body)
15. 4 NeoPixels
16. LiPo battery (1100 mAh)
17. Circuit Playground Bluefruit
18. HP Otto Robot (with extensions and tracks, but can also be used with the basic version if the button is not needed)
19. Sewing machine
20. Embroidery machine
21. Tailor scissors
22. Thread scissors
23. Fabric marking pens
24. Sewing and embroidery needles
25. USB-C data cable
26. Micro-USB data cable
27. Soldering iron
28. Solder with flux
29. Third hand tool
30. Multimeter

Print and cut the required pattern pieces, In my case, I used:

1. Monarch Large Hindwing (O1)
2. Monarch Large Forewing (N1)
3. Standing pose (A–E)
4. Wavy antennae (K1)
5. Arms (L)
6. Legs (E)
7. Neck fluff (M)

Create a small pouch consisting of a front and back panel to hold the LiPo battery (see photo). Make it slightly larger than your LiPo battery so it fits easily.

Cut the pattern pieces and prepare them for sewing.

Embroider the eyes and wing decorations according to the pattern instructions. I chose:

1. Starry Eyes (E7) and
2. Monarch Wings Applique (E30)

Apply conductive fabric patches to the back side of each wing. These will later function as capacitive touch sensors.

Cut the fabric pieces and follow the sewing instructions from the pattern.

Attach the battery pouch to the front body piece (C) after step 14 of the pattern instructions. Use a snap fastener to close the pouch.

If the snap fastener is conductive, cover the back with non-conductive iron-on volume fleece to avoid short circuits.

I added pipe cleaners into the wavy antennae (K1) for stability before sewing them on.

To stabilize the wings, it is advisable to iron volume fleece onto the wrong side of the fabric before sewing. This is because no conductive armor is inserted.

I also used iron-on volume fleece to attach a circle the size of the Circuit Playground Bluefruit (at the height where the Circuit Playground Bluefruit will later be attached) to the wrong side of the body front (C) to reinforce this area (see picture).

Stuff the moth with polyester filling according to the pattern instructions.

Don't forget to stuff the space between the belly and the battery pouch so the pouch can still be accessed but is not sewn into later.

Solder 5 mm sew-on snap studs to all pads of the Circuit Playground Bluefruit. This makes the electronics removable and reusable.

Follow this guide by Becky Stern and Adafruit: Adafruit FLORA Snaps Tutorial

Test whether the sockets hold onto the studs without any problems.

Sew snap sockets to the fabric at the positions of the following pads:

1. A1
2. A3
3. A4
4. A5
5. A6
6. VOUT
7. GND (next to TX)

Use the upper and lower holes of the socket and non-conductive sewing thread. To mark the points for sewing, the corresponding sockets, attached to their respective studs, can be dipped in an ink pad and then pressed onto the fabric. More sockets can also be sewn on if the PCB wobbles too much.

Attach four NeoPixels to the corresponding snap sockets using conductive thread, as shown in the picture.

1. Connect GND first
2. Then VOUT
3. Finally the data line

The data line should connect to the snap socket at pad A6. Use a multimeter to check for short circuits.

Do not sew the threads too close together so that the electric fields do not interfere with each other. Be sure to use VOUT for the power supply, as 3.3V is not sufficient.

Sew with conductive thread from the applied conductive fabric patches on the wings to the corresponding snap button sockets:

1. A1
2. A3
3. A4
4. A5

Again, use the multimeter to rule out short circuits.

Install the required firmware on both devices according to the instructions provided by HP Otto Robot and Adafruit:

1. CircuitPython on the Circuit Playground Bluefruit
2. MicroPython on the HP Otto robot

Upload the source code to both devices and add two sound files. My moth meows when shaken and says “I love you” when communicating with Otto.

You can find the Python files on my GitHub Repository. The code.py needs to go onto the Circuit Playground Bluefruit and the main.py file onto Otto.

Attach the LiPo battery to the Circuit Playground Bluefruit.

Then, attach the Circuit Playground Bluefruit to the corresponding snap sockets and insert the battery into the pouch.

Turn the power switch on and test the interactions:

1. The external NeoPixels should light up in turquoise
2. Touch the conductive wing appliques to change the internal LED colors of the Circuit Playground Bluefruit
3. Shake the moth to trigger sound
4. Press button A to trigger the HP Otto robot and the moth's reaction