Recently I have been investigating different ways of simplifying the incorporation of the BBC micro:bit in e-textile projects. Currently the two main options are the use of crocodile clips or directly sewing the micro:bit into the project. The use of crocodile clips is a simple option, however they tend to be bulky and aren’t suitable for smaller projects. Whereas sewing the micro:bit directly into the project prevents the micro:bit being used for other purposes. This can be an issue, particularly when the number of micro:bits available is limited. Another option is the use of a breakout board specifically designed for e-textiles such as the Kitronik Klip Halo. However, if multiple boards are required it can become an expensive option.
As an alternative I have been working on a 3D printed holder that can be sewn into a project. It uses conductive thread to create contacts for the micro:bit and allows the board to be inserted and removed from the project as needed.
The example circuit shown in the photo uses the micro:bit holder to create a circuit which controls two sewable LEDs. A switched, 3v coin cell holder is used to power the micro:bit. The contacts for the micro:bit are created using 6 to 8 rounds of conductive thread. The top three tabs of the holder are held in place using ordinary thread. When the micro:bit is inserted it should sit slightly underneath the bottom tabs, this ensures connection with the contacts. When the holder has been sewn in place it should be tested as you may find additional conductive thread needs to be added to some of the contacts to ensure a consistent connection to the micro:bit.
The current version of the holder is designed for V1 of the micro:bit, I will update it when I have access to a V2 board. The video below shows a simple project running on the e-textile circuit.
The STL file for the micro:bit holder can be found below: