ninjanirs2024

 

 

 

System Overview

The ninjaNIRS 2024 is the latest version of the ninjaNIRS whole-head, high-density fNIRS device (DOI link). This updated system retains its modular design and supports up to 200 optodes, with a maximum of 56 sources and 144 detectors, capable of dual-wavelength fNIRS data acquisition. Among the major improvements in the 2024 update is a newly developed Casing—designed by Bilal Siddique at the Intelligent Biomedical Sensing Lab— streamlining the system for portable and naturalistic data collection. Additional advancements such as the ninjaWeb wireless interface, updated Source Interface Cards, and a redesigned Backplane and IMU units were incorporated with support from the Boston University Neurophotonics Center.

Key Resources for Setting Up the ninjaNIRS System

The following are essential resources for assembling, configuring, and using your ninjaNIRS system:

  • ninjaManual: A comprehensive technical manual that guides users through the entire process of assembling a ninjaNIRS system—from ordering components and PCBs to successfully collecting data for the first time.

  • ninjaNIRS Technical Documentation: A GitHub repository containing all relevant hardware design files, firmware, and CAD models required to build and operate the ninjaNIRS system.

  • AtlasViewer: A MATLAB-based tool used to design custom montages for fNIRS data acquisition.

  • ninjaCap: A processing pipeline that generates 3D-printable TPU-based flexible caps based on montage designs created in AtlasViewer.

  • ninjaGUI: A MATLAB-based graphical user interface for wired data acquisition with the ninjaNIRS system.

  • ninjaWeb: Firmware for enabling the web-based ninjaWeb interface, allowing wireless data acquisition and monitoring using the onboard Raspberry Pi Zero 2W.

Casing

The most significant hardware change is the redesigned enclosure. The new case reduces overall system size by eliminating unused internal space. It also improves cable management by housing the splitter PCBs within the enclosure itself, thereby removing the need for external ribbon cables and increasing durability.

ninjaWeb Interface

A new web-based interface, ninjaWeb, in now fully operational. It supports wireless control, visualization, and real-time monitoring of data using the onboard Raspberry Pi Zero 2W. This interface is designed to simplify experiment management and eliminate the need for a wired setup during mobile data acquisition. All acquired data is stored on the SD Card and can be downloaded wirelessly.

Source Interface Card

A new RP2040 microcontroller has been integrated into the source interface card. This enables more flexible source multiplexing, allowing multiple sources to be activated simultaneously at different power levels. Additionally, LED drive currents are now controlled by a 16-bit DAC, allowing for precise and independent control of light intensity.

Backplane

The backplane has been redesigned to use wire-to-board connectors, which now interface with the control board via ribbon cables. This is a shift from the ninjaNIRS 2022 system, where separate source and detector backplanes were used. In the 2024 version, these have been consolidated into a single, unified backplane, improving integration, reliability, and assembly.

IMU Units

The IMU units have been refined to be more compact. These smaller units are easier to wear and place on the body, improving usability in mobile recording setups. Each unit still supports 6-axis motion sensing and connects to the system through the IMU interface card and splitter board. The ninjaNIRS system supports up to 8 IMU units in total.

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