What is the difference between Flow1 and Flow2?

Flow2 represents a step-change in the capability and quality of our TD-fNIRS technology - making it the best optical brain imaging system in the world. 

Flow2 is our production grade TD-fNIRS system and the next generation of our prototype, Flow1. While both models use advanced TD-fNIRS technology, Flow2 has nearly twice as many channels and is built around an entirely new detector application specific integrated circuit (ASIC), which provides even higher sensitivity and dynamic range, all while using less power. The Flow2 headset has also been redesigned for superior fit, maintains better coupling in the presence of hair, and provides a more uniform image of functional brain activity across the whole head.

Before Flow2, the Flow1 prototype systems were shared with early adopters and cutting edge research customers. These systems were used to gather feedback from the community about the strengths and weaknesses of the Flow1 prototype. Any studies done using Kernel systems prior to 2023 were done using the Flow1 prototype system. Several presentations have been given and papers published with results from the Flow1 prototype systems. An unordered partial list of Flow1 presentations and papers is:

• [Peer-reviewed publication] Ban, H. Y., Barrett, G. M., Borisevich, A., Chaturvedi, A., Dahle, J. L., Dehghani, H., Dubois, J., Field, R. M., Gopalakrishnan, V., Gundran, A., Henninger, M., Ho, W. C., Hughes, H. D., Jin, R., Kates-Harbeck, J., Landy, T., Leggiero, M., Lerner, G., Aghajan, Z. M., … Zhu, Z. (2022). Kernel Flow: a high channel count scalable time-domain functional near-infrared spectroscopy system. Journal of Biomedical Optics, 27(7). https://doi.org/10.1117/1.JBO.27.7.074710

• [Peer-reviewed publication] Ortega-Martinez, A., Rogers, D. ’ja, Anderson, J., Farzam, P., Gao, Y., Zimmermann, B., Yücel, M. A., & Boas, D. A. (2022). How much do time-domain functional near-infrared spectroscopy (fNIRS) moments improve estimation of brain activity over traditional fNIRS? Neurophotonics, 10(1), 013504. https://doi.org/10.1117/1.NPh.10.1.013504

• [Conference presentation] Oveisi, P., Clappison, A., Momi, D., Griffiths, J. Reliability and consistency of diffuse optical tomography resting-state functional connectivity measurements from the Kernel Flow fNIRS system. Poster presented at the 15th Canadian Neuroscience Meeting (2022)

• [Preprint] Castillo, A., Dubois, J., Field, R. M., Fishburn, F., Gundran, A., Ho, W. C., Jawhar, S., Kates-Harbeck, J., Aghajan, Z. M., Miller, N., Perdue, K. L., Phillips, J., Ryan, W. C., Shafiei, M., Scholkmann, F., & Taylor, M. (2023). Acute effects of subanesthetic ketamine on cerebrovascular hemodynamics in humans: A TD-fNIRS neuroimaging study. In bioRxiv (p. 2023.01.06.522912). https://doi.org/10.1101/2023.01.06.522912

• [Preprint] Dubois, J., Field, R. M., Jawhar, S., Jewison, A., Koch, E. M., Aghajan, Z. M., Miller, N., Perdue, K. L., & Taylor, M. (2023). Change in brain asymmetry reflects level of acute alcohol intoxication and impacts on inhibitory control. In bioRxiv (p. 2023.01.10.523048). https://doi.org/10.1101/2023.01.10.523048