University of Oulu

J. Hakala, J. Kilpijärvi, M. Särestöniemi, M. Hämäläinen, S. Myllymäki and T. Myllylä, "Microwave Sensing of Brain Water – a Simulation and Experimental Study Using Human Brain Models," in IEEE Access, vol. 8, pp. 111303-111315, 2020, doi: 10.1109/ACCESS.2020.3001867

Microwave sensing of brain water : a simulation and experimental study using human brain models

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Author: Hakala, Jaakko1; Kilpijärvi, Joni2; Särestöniemi, Mariella3;
Organizations: 1Faculty of Information Technology and Electrical Engineering, Optoelectronics and Measurement Techniques Research Unit, University of Oulu, 90014 Oulu, Finland
2Faculty of Information Technology and Electrical Engineering, Microelectronics Research Unit, University of Oulu, 90014 Oulu, Finland
3Centre for Wireless Communications, Faculty of Information Technology and Electrical Engineering, University of Oulu, 90014 Oulu, Finland
4Faculty of Medicine, Research Unit of Medical Imaging, Physics and Technology, University of Oulu, 90014 Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 26.3 MB)
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Language: English
Published: Institute of Electrical and Electronics Engineers, 2020
Publish Date: 2020-08-14


This paper introduces a microwave-based approach that aims to non-invasively measure water, particularly cerebrospinal fluid (CSF) dynamics, in the human brain. The microwave measurement technique is well-known in industrial applications. More recently microwave techniques have awakened interest also in biomedical applications. This is the first time it is suggested to be utilized in measurements of brain water, particularly of CSF. Two different head phantoms were built in order to validate the sensitivity of the technique to sense dynamic variations of CSF and water volume inside a human skull. These were comprised of multilayered head phantom, including a real human skull, mimicking the electromagnetic properties of a human head. In addition, the variation of the CSF is evaluated with electromagnetic simulations using a planar layer model and a hemispherical layer model. Moreover, propagation and power flow inside the head model is evaluated using 2D power flow presentations. Reflection sensor principle was selected due to its simplicity and ability to measure relatively thick samples. Importantly, reflection sensor requires only one-port measurement making it very feasible for in vivo brain monitoring. In addition, the measurement setup does not require attachment of the sensor to the head, thus the measurement can be realized also without touching the head. Our experimental study as well as simulation results demonstrated the possibility to non-invasively sense, by microwaves, small dynamic variations in CSF volume in the brain, in particularly in the subarachnoid space.

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Series: IEEE access
ISSN: 2169-3536
ISSN-E: 2169-3536
ISSN-L: 2169-3536
Volume: 8
Pages: 111303 - 111315
DOI: 10.1109/ACCESS.2020.3001867
Type of Publication: A1 Journal article – refereed
Field of Science: 213 Electronic, automation and communications engineering, electronics
Funding: This work was supported in part by the Academy of Finland (6Genesis Flagship 318927) under Grant 314502 and Grant 318347.
Academy of Finland Grant Number: 318927
Detailed Information: 318927 (Academy of Finland Funding decision)
314502 (Academy of Finland Funding decision)
318347 (Academy of Finland Funding decision)
Copyright information: © The Authors 2020. This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see