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Human Research Program

Multi-Use Near-Infrared Spectroscopy System for Spaceflight Health Applications

Completed Technology Project

Project Introduction

FINAL REPORTING--FEBRUARY 2015 We achieved our overall objective by completing and testing our NINscan-M v2 prototype. Major achievements were: NINscan-M Development • NINscan-M Prototype: NINscan-M is the smallest, lightest, lowest-power and easiest to use NIRS hemodynamic imaging system available. Our modular design enables flexible deployment for spaceflight or analog missions and a broad range of Earth-based clinical and research applications. • NIRS Sensors: We developed and tested 3 sensors: (i) a large, 64-channel imaging sensor optimized for broad-area strip imaging, (ii) a more compact 64-channel imaging sensor optimized for regional imaging, and (iii) a quad point sensor that can monitor 4 separate sites simultaneously. • Biopotential Inputs: The 8-channel analog input provides flexible biopotential recording with 24-bit resolution at 250 Hz, including simultaneous acquisition of multi-channel ECG, EMG, and/or EOG, as desired. • Auxiliary Inputs: Four user-input buttons, a tri-axial accelerometer, a temperature sensor, and a force sensor (sensitive up to 100-lb) were also incorporated. • Power: Power can be switched between AA batteries and A/C adapter plug-in. • GUI: A graphical user interface was developed for monitoring the NINscan-M Bluetooth data for real-time interactive recordings and data quality assurance applications. NINscan-M was also integrated with our separate SpaceMED data acquisition system, allowing real-time NINscan-M data management. • Ease-of-Use Features: (i) single-switch (on/off) system operation, (ii) automatic gain-control built into the power-on sequence to optimize signals for all NIRS channels, (iii) modular (pluggable) auxiliary channels enable selection of only those sensors required for any given application, and (iv) Bluetooth communication along with developed GUI enable real-time data monitoring and quality assurance. NINscan-M Demonstrations • Oxygenation changes during muscle contraction were imaged while measuring EMG and force production. Such data can be used to assess muscle endurance in multiple muscles simultaneously, as well as muscle strength assessments. • Imaging of low-amplitude, regional oxygenation changes during functional brain activation was achieved. • Demonstrated low-noise 9-lead ECG measurements at 250Hz. • Demonstrated simultaneous multi-channel ECG, EMG, and EOG recordings. • Demonstrated synchronized accelerometry, force, temperature, and user-button inputs. Additional Achievements • Tested the NINscan technology in a parabolic flight campaign (4 flights; 19 subjects). • Published the first 24-hr continuous brain hemodynamic monitoring, using the NINscan technology. • Conducted and published the most detailed study to date investigating the sensitivity of NIRS to brain tissue. • Developed novel data analysis techniques for NIRS data to help correct deep-tissue measures for skin color and fat layers. • Discovered the sensitivity of our NIRS instruments to intracranial brain motion. ANNUAL REPORTING IN OCTOBER 2014 We completed most of our first functioning NINscan-M recorder (v1) in year 1, providing the first truly wearable 64-channel NIRS imaging system. During Year 2, we completed it and focused on testing v1 and a developing a second-generation device (v2) to miniaturize the system and improve sensitivity and functionality. The v2 system is now fully designed and boards are being fabricated and populated. Important achievements during the 2nd year of the project include: Enhanced NIRS sensitivity: Automatic gain-control has been incorporated for both the light sources and detectors. This will increase the dynamic range of the system 20x to 60x, which is a key feature for collecting suitable data for imaging applications. We have also redesigned the power supply circuit to reduce noise and to enable power-supply switching between untethered battery use and wall-power. Imaging Sensors: Two new sensors are being fabricated, including an optimized 64-channel imaging sensor, and a 4-arm, multi-site sensor. The imaging sensor will optimally utilize the system's dynamic range for higher sensitivity and higher resolution imaging. The multi-site sensor will enable monitoring of multiple regions of the body simultaneously (e.g., bilateral brain assessment, or simultaneous head, arm and leg measurements). Auxiliary Inputs: The 8-channel analog input enables recording of a wide range of signals (e.g., EMG, ECG, and/or EEG). These are collected with 16-bit resolution at 250Hz, just like NIRS data. A tri-axial digital accelerometer, a digital temperature module, and a force sensor used to sense force up to 100lb have also been incorporated into the system. User Interface: The Bluetooth module was activated and tested for wireless data streaming. This was then integrated with our separate SpaceMED data acquisition system, allowing real-time viewing and archiving of NINscan M data as it is streamed off via a wireless Bluetooth connection. Analog Testing: To identify any operational issues or constraints for such multi-modal monitoring, we tested the base NINscan technology during a parabolic flight campaign, including simultaneous NIRS, ECG, and accelerometry. This allowed us to assess the feasibility of using NINscan in analog/operational settings, to evaluate the performance of our technology in-flight versus on the ground, and to assess the sensitivity of our technology to cerebral alterations associated with gravitational changes. NINscan v1 represents the smallest, lightest, and lowest-power NIRS imaging system currently in existence, and v2 will be approximately a third the size of v1. While further characterization, human testing, and validation will occur in year 3, the flexible design will enable deployment in a variety of settings or for a variety monitoring needs. These range from general medical risks, to intracranial pressure risks, musculoskeletal risks, radiation risks, behavioral and performance risks, and cardiovascular risks. More »

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