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. Author manuscript; available in PMC: 2022 Jun 1.
Published in final edited form as: Curr Opin Biomed Eng. 2021 Feb 3;18:100272. doi: 10.1016/j.cobme.2021.100272

Figure 1.

Figure 1.

The figure illustrates the growth of fNIRS publications from 1993 to 2019 as assessed on October 31st 2020, and our predictions for the period 2021 to 2024. The dashed black line represents the growing trend, and the black dots indicate the prediction (2017 to 2019) in our previous paper [6], showing that real publications in the last three years match well with the prediction. We expect the total number of fNIRS papers to continue to grow in the next several years as we illustrate with the magenta bars. This graph also highlights the growth of papers published utilizing multimodal measurements or wearable fNIRS since its first implementation in 1998. These statistics were obtained from a database created by a Web of Science search with the search terms ‘fNIRS’ and ‘brain’. ‘Multimodal’ refers to synchronous measurements of fNIRS and other neuroimaging modalities. Search keywords for multimodal fNIRS studies were a combination of ‘fNIRS’ and any one of the following words: ‘multimodal’, ‘bimodal’, ‘hybrid’ or ‘EEG’. Search keywords for wearable fNIRS studies were a combination of ‘fNIRS’ and any one of the following words: ‘wearable’, ‘wireless’, ‘fiberless’ or ‘modular’.