Development of a fiber-less fNIRS system and its application to hair-covered head

Yamada, Tōru; Ohashi, Mitsuo; Umeyama, Shinji

doi:10.1117/12.2036155

Cited by 5 publications

(4 citation statements)

References 5 publications

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“…Subjects with little, light, thin, or no hair were preferentially selected, because fNIRS signal quality can be detrimentally affected by thick or dark hair, which is highly absorbent of NIRS light. Specialised hardware and probing techniques to overcome this problem are the subject of ongoing research [35] , but are beyond the scope of this research. Ethical approval was obtained as part of the Programme of Work ERN_17-0544P at the University of Birmingham, U.K. (reference ERN_17-0544AP4), with all subjects providing written informed consent prior to participating.…”

Section: Methodsmentioning

confidence: 99%

System Derived Spatial-Temporal CNN for High-Density fNIRS BCI

Dale

O’Sullivan

Howard

et al. 2023

IEEE Open J. Eng. Med. Biol.

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An intuitive and generalisable approach to spatial-temporal feature extraction for high-density (HD) functional Near-Infrared Spectroscopy (fNIRS) brain-computer interface (BCI) is proposed, demonstrated here using Frequency-Domain (FD) fNIRS for motor-task classification. Enabled by the HD probe design, layered topographical maps of Oxy/deOxy Haemoglobin changes are used to train a 3D convolutional neural network (CNN), enabling simultaneous extraction of spatial and temporal features. The proposed spatial-temporal CNN is shown to effectively exploit the spatial relationships in HD fNIRS measurements to improve the classification of the functional haemodynamic response, achieving an average F1 score of 0.69 across seven subjects in a mixed subjects training scheme, and improving subject-independent classification as compared to a standard temporal CNN.INDEX TERMS fNIRS, brain-computer interface, neural network, machine learning, CNN IMPACT STATEMENT The unique and often overlooked interdependence between fNIRS probe design and neural network architecture is demonstrated. A novel and effective BCI model is presented, which can be generalised to multi-wavelength, broadband, and hybrid fNIRS data.

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Section: Methodsmentioning

confidence: 99%

System Derived Spatial-Temporal CNN for High-Density fNIRS BCI

Dale

O’Sullivan

Howard

et al. 2023

IEEE Open J. Eng. Med. Biol.

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“…Note there are also several commercially available wearable systems that are not described here. These include the Brite 23 (Artinis Medical Systems, The Netherlands), 42 the Genie (MRRA), 43 and systems from fNIRS Devices, 44 Spectratech Inc., Japan, 45 – 47 and Shimadzu Corp., Japan 48 . These devices are not discussed here because they either do not meet our review criteria or have not been described sufficiently in peer-reviewed publications.…”

Section: Control-cabled Systemsmentioning

confidence: 99%

Review of recent progress toward a fiberless, whole-scalp diffuse optical tomography system

Zhao

Cooper

2017

Neurophoton

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, "Review of recent progress toward a fiberless, whole-scalp diffuse optical tomography system," Neurophoton. 5(1), 011012 (2017), doi: 10.1117/1.NPh.5.1.011012. Abstract. The development of a whole-scalp, high sampling-density diffuse optical tomography (DOT) system is a critical next step in the evolution of the field of diffuse optics. To achieve this with optical fiber bundles is extremely challenging, simply because of the sheer number of bundles required, and the associated challenges of weight and ergonomics. Dispensing with optical fiber bundles and moving to head-mounted optoelectronics can potentially facilitate the advent of a new generation of wearable, whole-scalp technologies that will open up a range of new experimental and clinical applications for diffuse optical measurements. Here, we present a concise review of the significant progress that has been made toward achieving a wearable, fiberless, high-density, wholescalp DOT system. We identify the key limitations of current technologies and discuss the possible opportunities for future development.

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“…This improved system was detailed in a previous report [19]. Briefly, the system has six high illumination LEDs as sources and six avalanche photodiodes as detectors.…”

Section: Implementation Of the Proposed Methodsmentioning

confidence: 99%

“…The holding mechanism was detailed in previous reports [19,20]. Briefly, adjacent optodes were cross-linked by two-layered linkage plates.…”

Section: Implementation Of the Proposed Methodsmentioning

confidence: 99%

Removal of motion artifacts originating from optode fluctuations during functional near-infrared spectroscopy measurements

Yamada

Umeyama

Ohashi³

2015

Biomed. Opt. Express

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Functional near-infrared spectroscopy (fNIRS) has been increasingly utilized for detecting human cerebral activity in many disciplines because of the potential for less-restraining conditions. However, users often suffer from motion artifacts originating from optode fluctuation during task execution when the task includes motion. In such cases, the optode fluctuation induces changes both in the reflection by hair and in the transmission between the optode and scalp. If part of the reflected light is directly received by the detector optode (short-circuited light), it will contaminate the fNIRS signal. The transmittance change at the optode-scalp gap will also contaminate the signal. In this study, we proposed an optical model on the influence of optode fluctuation on the fNIRS signal and a method for removing the influence. The model revealed the following: (1) the received short-circuited light and the gap transmittance change generated a baseline change in the detected light intensity, and (2) the signal from the tissues was downscaled with increases in the receiving intensity of short-circuited light. To avoid erroneous detection of short-circuited light, we developed a method that optically eliminated hair-reflected light from the detection using linearly polarized light sources and an orthogonally polarized analyzer. The method was validated with an optical phantom possessing a haired surface. The optical absorbance change of a close source-detector (S-D) pair equipped with polarizers was very similar to that of distant S-D pairs, even though these optodes were artificially fluctuated. By combining the multidistance optode arrangement technique with the short-circuited light elimination method, the measurement could effectively eliminate motion artifacts originating from optode fluctuation.

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Development of a fiber-less fNIRS system and its application to hair-covered head

Cited by 5 publications

References 5 publications

System Derived Spatial-Temporal CNN for High-Density fNIRS BCI

System Derived Spatial-Temporal CNN for High-Density fNIRS BCI

Review of recent progress toward a fiberless, whole-scalp diffuse optical tomography system

Removal of motion artifacts originating from optode fluctuations during functional near-infrared spectroscopy measurements

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