Play games with your brain signals using Octopus 16 wireless EEG device

Octopus 16 is a wireless biosignal HID device for the XIAO ESP32-S3 board designed to let users play computer games using brain signals (EEG) with no hands (or implants) needed.

The board packs 16 electrodes to measure biosignals, including EEG (electroencephalography), EMG (electromyography), and ECG (electrocardiography), and the coin-sized device is much more compact than other brain-computer interface (BCI) solutions, which typically require a cap kit with 8 to 16 electrodes and wires.

Octopus 16 specifications:

• ADC – 2x Texas Instruments ADS131M08 24-bit, 8-channel, simultaneous-sampling, delta-sigma (ΔΣ) analog-to-digital converters
• Channels – 16x 24-bit channels (8x per ADC)
• Programmable gain (PGA) – x1 to x128 (set in firmware; default gain register 0x2222)
• Input high-pass / DC block – Integrated ADC DC-block filter enabled (≈ >1 Hz)
• Host interface (to XIAO board) – Power + SPI via 2x 7-pin
• Brain interface
  • 18x spring-loaded pogo pins
    • 16x electrodes
    • 1x  reference (AINREF)
    • 1x Ground (GND)
  • Pin pitch (center-to-center) – About 5.38 mm (uniform hexagonal packing)
  • Array span – 20.3 × 20.3 mm, all pins within a ~10.5 mm radius of center
  • Reference/ground routing – Selectable via on-board jumpers (AINREF_POGOPIN_ON, AINREF_STACK_ON, GND_ON, STACK_1/2) for stacking or single-board use
• Misc – 3D printed enclosure
• Power Supply – 5V via headers (via USB-C port on XIAO ESP32-S3)
• Dimensions – 26mm Ø (4-layer PCB)

The Octopus 16 then needs to be connected to a XIAO ESP32-S3 or XIAO ESP32-C6 board, powered by USB, for instance a USB-C power bank,  and placed on your head so that all 18 pogo pins are in contact with your skull. The XIAO board then acts as a BLE HID gamepad, and integrates with the PiEEG open-source server.

The software part of the project is open-source; you’ll find the Arduino sketches and Python programs on GitHub, while the hardware and software documentation can be found on the PiEEG website. You can check out an online demo/simulation without hardware using a virtual 8-channel device by clicking “Launch Demo”. That demo also links to a range of compatible games.

PiEEG also shared a video demo showing how one of the developers could exit a maze by just thinking about it. Based on the demo, this type of device won’t replace a mouse and keyboard anytime soon, as while it did work, it was a bit of a struggle.

Another video shows how to get started with the Octopus 16.

We’ve been writing about Ildar Rakhmatulin and Youssef El Abbass’ brain-computer interface projects for a few years, covering devices such as the Raspberry Pi 5-based PiEEG laptop kit, the PiEEG shield for Raspberry Pi, and the ardEEG shield for Arduino UNO R4 WiFi. The Octopus 16 relies on the same principle, but it’s their most compact device so far.

It’s still somewhat pricey, with the Octopus 16 selling for $250 on Elecrow. You’ll also need to add a XIAO ESP32-S3 board, a battery, and optionally print the enclosure for it.

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