Flex Modules

Wearable breakout boards.
Flex Modules have 2.54mm castellations for breadboard and solder on to wearable flexible PCBs

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Fyber Labs is designing wearable devices utilizing flexible PCB.

To reduce time and cost, we created Flex Modules that merge the non-form factor breadboard and alpha form factor prototype steps. Flex Modules will be able to go direct from breadboard to wearable. We are releasing Flex Modules OSH/OSS so that other makers can rapidly prototype. If there is interest, we will start selling pre-made modules as well.

Flex Modules are tiny 3.3V (only) rigid PCB modules including ARM Cortex microcontrollers, Bluetooth BLE, and sensor components. Each module will have its own project and details. We will be publishing schematics, layouts, and even the boards as components in DipTrace compatible format. Demo projects, build instructions, BOMs, Gerbers, and OSHPark order links will be provided.

We welcome feedback and new project contributors. See the System Design document for more information.

The general goal is to make a 'kit' of reusable components for wearables.
Bluetooth BLE is the standard for communications. WiFi, etc. require too much power and anyone with a wearable likely has an Android or iOS phone. All wired connections are USB based as it is the only durable and cheap connector in the world.

Sub goals:

  • Open source hardware and software (BSD, MIT, and GPL)
  • Castellated modules (2.54mm)
  • 3.3v only
  • ARM Cortex with open tool chain
  • Support Kapton or other flexible PCB
  • Utilize common open prototype methods - OSHpark, OSH Stencils

Soft goals:

  • Approximate module size of 0.7x0.5" or smaller
  • Espruino JavaScript compatible stack
  • Support open API standards for IoT
  • Common GND/3.3v castellation positioning

Flexible PCB Howtos:

We made some posts some time ago on this, but never linked them in till now. This should help people get started with their own home made flexible PCB designs.


Designed/In Progress:


  • Pressure, weight, stretch based sensors
  • Electro dermal activity(EDA) (probably just a reference flexible PCB based probe design)
  • Connectors, etc. as needed that don't mount on flex well
  • OLED displays (SSD1351 and SSD1306 or something like Sharp's memory LCDs)
  • WiFi
  • LTE
  • GPS
  • NFC


Sewable Flex Modules

Demo Projects:

Accessory Projects:

Personal Lighting

Social Authentication and Authorization

Related drivers and demos will be licensed under BSD or MIT licenses depending on original source if any. We will release online or cloud related software under AGPL, GPL, or LGPL licenses.

Creative Commons License

  • 1 × STM32F401CC Microprocessors, Microcontrollers, DSPs / ARM, RISC-Based Microcontrollers
  • 1 × nRF51822 Bluetooth BLE Microcontroller
  • 1 × Plessey EPIC 254xx or 252xx sensors ECG/EMG sensors
  • 1 × LSM9DS1TR 9-axis gyro
  • 1 × BME280 Barometer

View all 17 components

  • More Flex Modules on Tindie

    Chris Hamilton03/24/2017 at 05:11 0 comments

    We will be selling more of our designs on Tindie.

    Over the next week, we will be adding much of the working designs on to our store -

    We will be adding more documentation here and some videos on youtube to demonstrate the Flex Module concept and various uses.

  • Sales this weekend

    Chris Hamilton11/26/2015 at 19:01 0 comments

    We are selling our Flex Modules on Tindie for 15% off -

    Use coupon code D721A61 at checkout!

  • License discussion

    Chris Hamilton08/18/2015 at 08:58 0 comments

    Licensing is a pretty complicated discussion, and I wanted to try to clarify our position since the HackadayPrize requires license declaration.

    We are releasing our SociACL and any related SAAS as AGPL to keep any usage of it open. I tend to prefer to use BSD license for drivers, but the MIT license is much simpler so for anything else that is code we make it, will default to that.

    I have updated the general repositories to show the MIT license, though the driver repository will be a mix and the individual files will likely contain their own licenses that may be a version of the BSD. We will only publish OSI approved licenses and retain the license of any drivers or other software we have made any derivative from.

    As for content on our blog content, images (excluding any servicemarks or trademarks), and anything else we will be using the following CC license:

    Creative Commons License

  • Pattern Improvements

    Chris Hamilton08/01/2015 at 18:05 0 comments

    Our last order from OSHPark I made the solder bridge spacing 10mil. These look much better and should be less of a challenge to solder. I'll be porting our castellation shape, solder bridges, and the Flex Module patterns to Eagle (and KiCAD) soon. We had a volunteer for some layout work and so I need to make our patterns more portable.

    I am still working on some firmware updates, especially to our haptic boards as they are so popular and the current libraries from Adafruit and Precision Microdrives are limited in features and testing.

    We got our initial TinyLED and rigid Light Square designs back from DirtyPCB and they look good. I'll test them and hopefully get some videos up of them soon. The accelerometer on the TinyLED is not going to work (I missed a couple of pins) on the initial design. I'll have a run ordered after testing that should work :).

    I have a bunch of samples in from Arrow (thanks ST, TI) and Coilcraft, so the new Flex Module projects I put up should be coming along. Many of the light sensing boards will take a few revisions to get right as they will have source LEDs that need experimental placement to be reflected accurately. Some boards take only a day. Some take months of testing.

  • Starting an adhoc open development program

    Chris Hamilton07/29/2015 at 20:59 0 comments

    We have tried a few times to get volunteers together and build a community. It is difficult to do in open source software, and even more difficult with open hardware. We need help with software development and to that end, we are willing to provide hardware to those willing to help develop drivers and libraries for our Flex Modules.

    See the page below for more information:

    Chris and Cindy

  • Sewpads soldering demo

    Chris Hamilton07/28/2015 at 02:38 0 comments

    We put up a simple guide on how to solder the Sewpads on to Flex Modules.

  • Etching flexible PCB

    Chris Hamilton07/23/2015 at 01:17 0 comments

    Cindy wrote up a post on how we current etch our own flexible circuit boards - .

    We used the 64x Light Panel shown in the blogs for our Indiegogo campaign -

    In addition, you can see our first run of sewpads.

  • New Indiegogo campaign for Light Square LED panel

    Chris Hamilton07/22/2015 at 09:16 0 comments

    Hi, we have started an Indiegogo campaign to group buy for our 5" Light Square. We plan to use Epec and their new InstantQuote flexible PCB ordering system to keep the price low.

  • Design updates

    Chris Hamilton07/16/2015 at 17:51 0 comments

    I believe I have an improved design with the i2c solder bridges. Most i2c devices in the latest designs have a solder bridge to optionally enable the i2c pull up resistors. In addition, the address solder bridges are closer together to simplify soldering. Almost all sensor and output boards are now 2 layer, so that should lower costs in the long run. I have all the boards up on Tindie (other than some new ones we will be making projects for shortly). I am still testing the microcontrollers and finishing drivers. So those boards, though up on Tindie will be out of stock till I feel they are really ready.

    I will be launching a tiny Indiegogo campaign to test interest in customizable flexible LED panels. The first up will be the 5" Light Square. We have some smaller rigid LED jewelry concepts that I will be experimenting with once the initial board run is delivered.

    The mini EL works better than expected and I am very happy with its design.

  • Updates

    Chris Hamilton04/25/2015 at 04:23 0 comments

    OK, well I have made most of the Flex Modules and I am still testing/finishing reference software. I am updating photos, information on the various Flex Module projects and placing them back on Tindie. We will be selling them through our own website as well hopefully in the near future to support WA customers. Cindy and I have a long list of demo projects we will be choosing to enter into the Hackaday Prize when we have time.

View all 32 project logs

  • 1
    Step 1

    Order Flex Modules from us or do it yourself with our gerber files in Github.

  • 2
    Step 2

    Design your own PCB using Flex Modules as components or use our demo Flex Module projects.

  • 3
    Step 3

    Get supplies needed for etching flexible PCB. Copper clad Kapton/polyimide can be bought on eBay relatively easily. Sheet or roll will work fine. Our demos only require single sided.

View all 8 instructions

Enjoy this project?



michcfr wrote 08/12/2014 at 08:28 point
Hi Chris,

Thank you for your response.

Just for information, the smallest coils I found are these one:

For bluetooth modules, I agree with you : plenty of certified nrf51822 modules are already exisiting on the market. I like the rfduino product. Small and not too much expensive.

Concerning the 4G/LTE module, or long range communication means in general, I think the smartphone approach is not in the spirit of wearable/connected object approach. The object/human to sense do not need human in the loop intervention (through the smartphone).
For Example, on your ECG project, you needed an independant/autonomous device collecting ECG data and log in SD card. So imagine the same device sending data over 2G/3G/4G in real time instead of log in into the SD card.
Shortly speaking, smartphones are made to connect ears and eyes. 4G modules should be dedicated for wearable/connected object. This is my one cent advice :-)

For 4G, I was thinking about the Huawei ME909TU module (already FCC and CE certified). As bonus, it integrates GPS receiver. Unfortunately I do not have electronics and soldering skills, I am rather software oriented. Do you have an idea on how I can get a full usable component with such module?


  Are you sure? yes | no

Chris Hamilton wrote 08/12/2014 at 08:48 point
Well for that module, I would recommend buying the devkit - . I don't see much documentation publicly available, but it appears to have embedded Linux/Android support and USB for firmware updates. You might want to contact Techship or a Huawei sales rep to get more documentation first. Once you have the devkit up, you should be able to do firmware work on it and worry about shrinking the hardware around it later.

  Are you sure? yes | no

michcfr wrote 08/12/2014 at 09:43 point
ok, I have downloaded the technical doc on their website. Do you think I can drive the module from the STM32F401 MCU (AT command)?

  Are you sure? yes | no

Chris Hamilton wrote 08/12/2014 at 10:14 point
Well from the limited specs available, I believe it has its own ARM processor. I don't think it needs any additional microcontrollers. It has quite a lot of peripheral I/O and there is one white paper I saw about updating embedded Linux on it.

  Are you sure? yes | no

Chris Hamilton wrote 08/12/2014 at 10:28 point
Sorry, that appears to be just how to push firmware from an embedded Linux. I guess it depends on what is easier to program. I would expect it to have a decent processor and it must be programmable, otherwise they wouldn't expose so much I/O. It may turn out to be easier to drive it by AT commands through something like the STM32F401 if the compiler is expensive or writing firmware is not well documented/supported by Huawei.

  Are you sure? yes | no

michcfr wrote 08/12/2014 at 11:21 point
Yes, AT command is the prefered interface to use the module and the embedded software seems to be opaque/closed. They provide drivers for Windows PC and Linux PC to operate the module. And the documentation about AT command is rich.
I like the Huawei ME909u variant. It is 30mmx30mmx2.3mm!
But my fear is not about programming the module through the STM32F401, it is about designing the PCB. It needs some electronic knowledge I don't have.

How can I influence your priorities about this module? :-)

  Are you sure? yes | no

Chris Hamilton wrote 08/12/2014 at 18:12 point
Sorry, working with hardware is a significant investment. Our product designs are specific to Bluetooth, so I don't see it as likely we can help. I would suggest starting your project here and lay out what you are planning to develop. You might be able to attract some hardware developer interest. Good luck!

  Are you sure? yes | no

michcfr wrote 08/12/2014 at 20:26 point
ok, good idea! Thx

  Are you sure? yes | no

michcfr wrote 08/11/2014 at 23:02 point
Hi Chris,
Impressive project! Exactly what I need as a baseline to start mine :-)
-QI charging receiver
-on/off switch hall effect sensor. Good in case of waterproof usage (no physical switch)
-4G/LTE module. Do you have the possibility to solder LGA chips?

When modules will be available ?

More questions and suggestions are coming :-)


  Are you sure? yes | no

Chris Hamilton wrote 08/12/2014 at 02:11 point
Hi, and thank you for your interest.
- I have looked in to Qi charging with TI components and it is something to think about. The coil is much bigger than the module footprint and would need mounted separately. It could work well in larger projects.

- I'll look into the hall effect switch, that might work well. We are hand coating boards with silicone conformal coating and also utilizing silicone for casing. Most of our designs just start up whenever USB is connected. I'll try to post some example projects we are working on soon so more people can understand the usefulness of the modules.

- 4G/LTE isn't a big priority for us. We would prefer a smart phone in the middle to lower power requirements and provide a UI. There are some comparable cellular modules in available. Flat (no exposed component) LGA modules should mount OK on most flexible PCB. Heck there are quite a few nRF51822 Bluetooth modules on the market(I wanted to do my own, though we may never sell it and move to off the shelf since selling would require significant investment in FCC certification).

The modules are technically available now if you want to load the layouts in DipTrace and send off the gerber files to OSHPark to make them yourself. (Some BOMs may be missing 1 or 2 components).

Right now I am working through my own small batch testing. Once I get the component spacing, solder mask, paste stencil, and castellation depth well tested I'll post the Gerber files on Github and put up links to order the unpopulated boards direct from OSHPark. If there is enough interest, we will do some full runs and/or negotiate with Seeedstudio or Sparkfun to handle production and selling.

I'll post demos and flexible PCB how-tos soon. Please keep the questions and suggestions coming!

  Are you sure? yes | no

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