Octopus 16 Puts 16-Channel EEG on a $250 Open Board

Brain-computer interfaces have a reputation for being either surgical or vaporware. The Octopus 16, covered by CNX Software on August 2, is neither: it is a 26mm circular PCB you place on your head, it costs $250, and its Arduino sketches and Python programs are on GitHub. It reads 16 channels of EEG and presents itself to a computer as a Bluetooth LE gamepad — which is to say, you can play games with it.

• 16 channels via dual Texas Instruments ADS131M08 24-bit ADCs, with programmable gain from x1 to x128
• 26mm four-layer board with 18 spring-loaded pogo pins (16 electrodes plus reference and ground)
• BLE HID gamepad output through a Seeed XIAO ESP32-S3 or ESP32-C6 host module
• $250 via Elecrow, with open-source Arduino and Python code and an optional 3D-printed enclosure

What Does the Octopus 16 Actually Measure?

More than the name suggests. The dual ADS131M08 converters handle EEG, but the same signal chain also reads EMG (muscle activity) and ECG (heart activity), with DC-blocking filters above 1 Hz built in. The electrode array is hexagonal, spanning 20.3 × 20.3 mm, and connects through 18 spring-loaded pogo pins — sixteen for signal, plus reference and ground.

Twenty-four bits of resolution with gain adjustable up to x128 is the specification that matters here. Biosignals are tiny and noisy; the headroom to amplify them cleanly is what separates a usable EEG front end from a random number generator. Running two eight-channel ADCs in parallel over SPI is a sensible way to reach sixteen channels without exotic parts.

How Does It Turn Brain Signals Into Game Input?

The board itself is the analog front end. A separate Seeed XIAO module — either the ESP32-S3 or the ESP32-C6 — acts as the host microcontroller, talks to the ADCs over SPI, and then advertises itself over Bluetooth LE as a standard HID gamepad. To the computer on the other end, it is simply a controller.

That design choice is quietly clever. By presenting as a generic BLE gamepad rather than requiring a bespoke driver, the Octopus 16 works with anything that accepts controller input, no integration work required. It is the same pragmatism we liked in the SensWear open-source wearable platform, which built modular sensor boards around a Nordic nRF54L15 instead of inventing a new protocol stack.

The project comes from Ildar Rakhmatulin and Youssef El Abbass, who have shipped several prior BCI projects, and it integrates with the existing PiEEG platform — including an online demo at cloud.pieeg.com for anyone who wants to see the signal processing before buying hardware.

Who Is This For?

At $250 plus a XIAO board, a battery and an optional printed enclosure, this is not an impulse purchase, but it is dramatically below where research-grade 16-channel EEG has historically sat. That puts it in reach of university labs, accessibility researchers, hobbyist neuroscience projects and the growing group of makers building assistive input devices.

Accessibility is the application worth watching. Hands-free input has real users with real needs, and every drop in the cost of a decent multi-channel front end widens the pool of people who can prototype for them. The Augmental MouthPad we covered in July approached the same problem from a completely different direction — the tongue rather than the scalp — and the fact that both now exist as accessible hardware is a genuinely good sign for the field.

The open-source side matters just as much as the price. Arduino sketches and Python programs on GitHub mean researchers can inspect the signal path rather than trusting a black box, and makers can modify it. For more open hardware in this vein, see our mini computers coverage.

Sources: CNX Software — August 2, 2026; PiEEG project — accessed August 2, 2026.