OpenEarable open-source hardware earable platform leverages Arduino Nano 33 BLE Sense ecosystem

OpenEarable is an open-source hardware earable, sometimes also called hearable, that fits around your ear and is based on the same u-blox NINA-B306 module found in the Arduino Nano 33 BLE Sense board.

Besides the Nordic Semi nRF52840 Arm Cortex-M4-based Bluetooth LE module, the design also features a speaker and ultrasonic microphone, a 6-axis IMU and a pressure sensor, as well as the circuitry for the battery, two LEDs, and a push button.

TECO Open Earable open source hardware device
Components description of an early sample of the Earable devkit (v0.2)

OpenEarable specifications:

  • Wireless module – U-blox NINA-B306 module powered by a Nordic Semi nRF52840 Arm Cortex-M4F microcontroller @ 64MHz with 1MB Flash, 256KB RAM, Bluetooth 5.0 LE connectivity
  • Audio – Built-in speaker and ultrasonic microphone (Knowles SPH0641LU4H-1)
  • Sensors
    • STMicro LPS22HBTR pressure and temperature sensor
    • STMicro LSM6DSRTR 6-axis IMU with accelerometer and gyroscope
  • USB – Micro USB port for power and programming
  • Debugging – Solder pads for SWD interface
  • Misc – Push button, charging LED, one programmable PWM LED
  • Power Supply – Battery, voltage regulator, and charging controller
OpenEarable Block Diagram
OpenEarable v1 Block Diagram

The OpenEarable firmware is implemented in C++ using the Arduino framework based on the implementation of the Arduino Nano 33 BLE Sense and can be found on GitHub, while the latest PCB layout and 3D files for the enclosure are available on the project’s page.

OpenEarable was designed as part of a research project by researchers from the Karlsruhe Institut of Technology and the University of Bath, where they demonstrated three applications of the platform: motion tracking to detect events such as standing still, walking, and jumping jacks using TinyML, ear canal pressure monitoring to detect jaw motion (e.g. chewing), and ear canal sound reflection to understand the shape of the ear canal which could potentially be used for authentication.

OpenEarable devkit

More recent versions of the Openearable design use two PCBs with wires between the mainboard and the microphone/speaker part as it must be more comfortable and adaptable to various ears than having a single PCB placed around your ear.

While the kit above looks like it may be ready for sale, it’s apparently not. You may try to contact the developers to get samples from the aforelinked project’s page, or manufacture it yourself. We’re told the design should cost around $40 per device for a batch of ten pieces.


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9 Replies to “OpenEarable open-source hardware earable platform leverages Arduino Nano 33 BLE Sense ecosystem”

    1. They are using an 18 KHz tone for “ear canal sound reflection”. I’m not sure this qualifies as “ultrasonic”, but they say this frequency is inaudible to the speaker.

      1. Oh, that’s interesting. I’m guessing if you have sufficient hearing loss to need an aid, you may have very little sensitivity to 18KHz, so it’s ‘ultrasonic’ for them, I guess.

  1. Nice there are open source alternatives but i don’t think anybody wants to walk around with such a huge thing on his ear, commercial ones are almost invisible

    1. I must admit I cringed when I saw the photo, too. Not because of the lack of elegance, but because of the raw PCB chafing against the ear. The newer version with the case and ear-bud on extender cables looks much more comfortable.

      I’m still cringing from where they suggest you keep the battery, though. 🙂

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