Temperature Sensing Nautilus Bag




Introduction: Temperature Sensing Nautilus Bag

This is a felted knit bag that incorporates a temperature/humidity sensor connected to NeoPixels and a display module. The light display varies with changing temperatures and accurate data is shown on the LED display in both Fahrenheit and Celsius.

Step 1: Materials Needed

Textiles (about $30-$50):

  • 11 balls of felting wool
  • #10 Knitting Needles
  • Dark wool roving (optional for needle felt accents)
  • Felting needles
  • Fabric for the bag lining
  • Zippers for the lining (to keep the electronics accessible)
  • Thin foam (protection for the electronics)

Electronics ($130- $140):

    Total Cost: $160-$190)

    Cheaper alternatives are likely to be around. I did learn the hard way though that sometimes some of these cheaper things don't work too well...

    Helpful tools:

    • Breadboard
    • Multimeter
    • Soldering equipment
    • Alligator clips
    • Sewing Machine

    Step 2: Knitting the Bag

    This project takes 11 balls of Felt Virgin Wool Ecru from Ice Yarns and number 10 needles. The pattern is based on the Chambered Nautilus Tam pattern by Elizabeth Zimmerman (Book: Knit One Knit All) with the modification of 1 stitch every 20 rows after the first 60 rows. Word of caution - this made for a complex knit and is not recommended for novice knitters!

    Reminder: For the two sides of the bags mirror images of the pattern need to be knitted. Again, not really for the beginner knitter...

    Either stitch or crochet the two sides together and think about the shoulder strap or handle. For this bag I simply added a strap (15 stitches) knitted as a tube that will later get attached at the other end.

    Obviously any shape or pattern would work for a bag like this. However, regardless of the shape or size of the bag, keep in mind that the felting process shrinks the project anywhere from 20-40%. It is highly recommended to knit/felt a swatch to better predict how much the final product will shrink.

    Step 3: Felting the Bag

    This is a rather large bag and thus easier to felt in the washing machine. It took about 20 minutes on the hot cycle and resulted in about 25% of shrinking. Careful monitoring during wet felting is recommended to avoid over-felting.

    To accentuate the spiral design of the nautilus needle felting was used to add darker shading.

    Tip: I was very impatient during this step and tried to needle felt before the bag was entirely dry - that cost me 5 felting needles! Once the bag is dry this step is MUCH easier so be patient.

    Step 4: Preparing NeoPixels

    These NeoPixels are not readily designed to be used in wearables. However, it is fairly easy to modify them so they can be sewn into projects. Use needle nose pliers to bend the prongs into small eyelets being careful to be keep track of the pins. To reduce confusion about which pin is which I marked them with sharpies (red for power and blue for ground - could not find my black sharpie...) and the data pins remained unmarked.

    I found out later that this was still not sufficient as I accidentally flipped a few data pins causing some (much) pain later on getting them right. If I were to do this again I would definitely mark each of the four pins individually to avoid input/output pins.

    Step 5: Sewing the NeoPixels

    Using conductive thread all prepared NeoPixels are sewn into the bag. This is worked from the wrong side of the bag and the bulbs are pushed through the felted knit so they are visible from the front (this is where the knitting approach really made life easy as I could take advantage of small holes already present).

    And yup, this is when I managed to get my wires crossed (literally) by inserting some of the NeoPixels backwards... Better preparation of the pins (see previous step) could have save a lot of aggravation here!

    Both the power and the ground pins are sewn with a continuous thread each while the data pins (running in the center) are connecting the input pin of one NeoPixels with the output pin of the other. Pay attention to the orientation of the data pins so the input for the strand is closest to the main board.

    Once the NeoPixels are in place it is time for the Lilipad and the power sources (see wiring diagram). At this point it is wise to work with alligator clips before committing to the hardware. Unlike more traditional electronics, undoing "sewn" circuits get very time consuming.

    Step 6: Adding the Lilipad and Power

    The final bag has two different power sources - one for the lights and the other for everything else. This was an adjustment that happened after finding out how power hungry the lights are (live and learn) and the pictures taken do not show the second power source until the end. Use the wiring diagram in the following step for clarification.

    The Lilipad main board and the first Lipower are placed and sewn to the bag. Conductive thread is used to connect the two with each other and to hook the NeoPixels to pin # 6. Any connections where conductive thread was cut and/or knotted is sealed with hot glue to secure the connections.

    Step 7: Wiring Diagram

    The wires of the graphic display module appear to be twisted in this diagram. However, this is intentional because display module gets flipped when placed on the outside of the bag.

    Step 8: Adding the Display Module and the Temperature Sensor

    While it is fun to have different colored lights indicating ambient temperature ranges, a more accurate reading truly satisfies the inner (and outer) nerd and is needed to show humidity. The monochrome graphic display module not only allows for that but can also handle a few extras like snowflakes when things drop below freezing or any other monochrome animation...

    The sensor and display module are first tested with a breadboard using the same power source as the Lilipad main board (the lights remain on their own circuit - LiPower/battery combo). See the previous wiring diagram for details.

    Once everything works - something that will doubtlessly require multiple rounds of tinkering (a nice bottle of Merlot helps ease the pain and is highly recommended here) the hardware gets installed in the bag.

    First cut a small (5x10 pin) piece of protoboard and solder the sensor and a 10K resistor in place. It was critical for this project to keep this component as small as possible so it would fit in the center of the spiral of the Nautilus. Solder silicon wires to the power, ground and data pins and feed the wires from the front of the bag to the back. In similar fashion the display module is soldered to silicon wires and installed in the bag (wires are pushed to the back before stitching the module down.

    The silicon wires that are attached to the sensor and display module are soldered to the appropriate pins on the Lilipad and LiPower (a little cardboard beneath the main board is sufficient to protect the textiles from the heat of the solder).

    Use the wiring diagram as a reference since the pictures are a little much!

    Step 9: Finishing Touches on Electronics

    In order to avoid stress on the connections and accidental pulling of the wires as the bag is in use, everything is hand stitched and fastened to the bag.

    Note: Neither the sensor nor the display module are visible in the first picture because they are placed on the outside of the bag.

    Also, I added a little bit more dark roving around the display module and carefully needle felted that in place to clean up the aesthetics.

    Step 10: Programming

    Please note that an interesting bug occurred. The sensor only works properly after the FTDI cable is unplugged and the bag is powered independently.

    Click Here To View On Github

    Step 11: Inside of the Bag

    The lining of the bag serves the purpose of practically and internal organization as well as the protection of the wiring and electronic components.

    It is important to remember that all components need to remain accessible after the lining is installed (large zipper does the trick). This makes it easy to reprogram the bag and trouble shoot issues as they no doubt will arise through the use of the bag.

    The lining also contains a pocket for the batteries which are connected to their respective LiPower sources via battery extension which makes battery removal for recharging much easier.

    Step 12: Adding the Switches

    An added benefit with the two battery approach is that the two circuits can be operated independently. This means that the main board, sensor and written display can stay all the time, but the lights can worked independently depending on power availability or circumstances.

    In addition, it would be very awkward to access the electronic panel on the inside of the bag each time to use the slide switch on the LiPowers and I wanted to make this as accessible as possible.

    I spliced the tactile switches into the JST extension cables so I could feed the switches into the the strap of the bag and easily operate them. This means that the LiPowers stay on all the time and power is controlled through the switches easily accessible.

    Again keeping with the theme of ease-of-use I placed the battery pouch right on the inside of the bag so that I do not have to go into the "guts" (between bag and lining where all the electronic components are). The JST extension cables reach out into that pouch and removing batteries to recharge them is as simple as taking out my cell phone.

    Step 13: Finishing

    Before sewing in the lining, a small piece of foam is placed over the electronics and held in place with a few stitches. The fully finished lining is then hand-stitched into the bag and voila - the bag is ready to be used and without a doubt start many a conversations.

    Arduino All The Things! Contest

    Runner Up in the
    Arduino All The Things! Contest

    Make It Glow! Contest

    Third Prize in the
    Make It Glow! Contest

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      5 years ago

      Beautiful fit and finish to your bag, it's amazing without the electronics... but of course the temperature and humidity sensing elevate it to a whole other level! Congratulations on becoming a finalist in the Arduino All Things! Contest!


      5 years ago

      Thanks everyone for your votes!

      This was such a fun project to make and I am happy others enjoy it too.

      svk28 - please do post pictures when you finish your version of the bag, I would love to see it :)


      5 years ago

      Wow, what an awesome and inspiring project!

      The only thing I would alter is making LEDs fade in and out smoothly (I believe it will improve the overall perception). It is quite easy to with NeoPixels, you can see example in my instructable: https://www.instructables.com/id/USB-NeoPixel-Deco-Lights-via-Digispark-ATtiny85/ (I can help with the code if you wish)

      By the way, probably using a NeoPixel strip (of 30 pixels per meter) would make this project a bit easier to do.


      Reply 5 years ago

      The fading is an excellent suggestion! Thanks. I am new to NeoPixels and will check your instructable on that to adjust the code - that will be pretty.

      As for the strip, I wanted to minimize any wire/cables for the lights to maintain higher flexibility on the bag. I like that the the bag is still nice and soft and molds to the body because of the individual LED's (important for such a large bag), but it really was rather tedious.


      5 years ago

      Hello again! I am working on actually knitting the nautilus bag, and I can follow the pattern as written just fine, but I am not quite sure how you made your modifications to increase the row width. When (with respect to the pattern) did you work your increases? How many rows total did you use (I am assuming way more than required for the tam, and it looks like you cast off without decreasing to a taper at the end... is this correct?)

      Thanks again! so excited to see how this turns out! I'll be sure to post pictures to you when I'm further along!


      Reply 5 years ago

      So cool you are knitting this bag!

      This is a tough question since I have knitted a bunch of other stuff since I basically forgot what I did. I went back to my notes but have to admit that they are very sloppy. So let me try to do the best here with what I remember and can reconstruct.

      The tricky part is that you need to adjust the short rows and stretch them out more as you go to avoid ruffling of the edge as you work it. I actually had to go back several times until I sort of figured it out.

      I ended up treating it as a three part knit:

      Part 1 (inner swirls): Regular Tam as described with full and short rows alternating. Keep increasing every 10th row until you have 23 stitches. In my picture you can see where this part ends and the red yarn markers begin for Part 2. Pay attention here how the knit behaves. I started to skip a short row with every increase by the time I got to 12-13 stitches because it started to ruffle (so skip every 10th short row). I think it will also depend on how tightly you knit etc.

      Part 2: To get a nautilus instead of a snail you need to increase more as you get into the final part of the shell. For this part you increase every 5 rows instead of every 10. Again, each time you increase on the full row you skip the short row to avoid ruffling (skipping every 5th short row). Repeat 7 times until you get to 30. Each increase is marked in my knit with a red bits of yarn so you can see where that part starts..

      Part 3: This is the little rounded end to make the shell a little more organic. For this part you start with a short row of 3 stitches and continue in a 3 stitch sequence: Short rows: 3, 6, 9, 12, 15, etc.

      I hope this made sense! Sorry if it is not entirely clear but it was a classic moment of trying to figure it out as I go without really trying to ever reconstruct.

      Did that help?


      Reply 5 years ago

      This does help quite a bit, thank you!


      5 years ago

      Such a great project, and what a gorgeous final product! I am very excited to try it, but I had a couple of questions:

      on your bill of materials, you have 2 soft switches. Where do they come into play? Forgive me if that is a naive question, but I didn't see them on the writing diagram, so I am wondering if you ended up using them.

      Also, if there a reason you went with the Sparkfun LilllyPad microcontroller instead of Adafrut's FLORA? Not advocating either one over the other, but I noticed most of your components were Adafruit and want to know if there is a specific reason to use the LillyPad for the brains of this operation.

      Again, fantastic project--thank you for sharing!


      Reply 5 years ago

      Wow that would be cool if you made your own bag!

      I added another step to explain the switch business - sorry for not mentioning that earlier. I am hoping that clarifies your question but let me know if it doesn't.

      I had made another bag earlier - it was based on the Chameleon Bag from Maker magazine and I included the video below- and found it invaluable to have an external easy accessible switch. (The switch is the little fabric square hanging out on the red lead.)

      As for my use of LiliPad vs. Flora that was no real preference but just what I had around. I had used LilyPad in my other projects so I went with that but honestly that was more by chance than anything else. You could use any microcontroller for this.

      On a side note though, I did initially play around with a LiliPad temperature sensor while figuring some stuff out and changed that to the more sophisticated DHT 22 because it is more sensitive and includes humidity.

      Would love to hear how things are going with your bag! Good luck and feel free to contact me again for questions :)


      5 years ago

      That bag is super cool even before the lights and the felting step!