University of Oulu

Measurements and characterization of optical wireless communications through biological tissues

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Author: Halder, Senjuti1
Organizations: 1University of Oulu, Faculty of Information Technology and Electrical Engineering, Communications Engineering
Format: ebook
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.3 MB)
Pages: 63
Persistent link: http://urn.fi/URN:NBN:fi:oulu-202007042732
Language: English
Published: Oulu : S. Halder, 2020
Publish Date: 2020-07-13
Thesis type: Master's thesis
Tutor: Katz, Marcos
Reviewer: Katz, Marcos
Bykau, Aliaksandr
Description:

Abstract

Radio frequency (RF) has been predominantly utilized for wireless transmission of data across biological tissues. However, RF communications need to address several challenges like interference, safety, security, and privacy, which often hamper the communications through the tissues. To mitigate these challenges, light-based communication can be exploited, as optical wireless communications have unique advantages in terms of security, interference and safety. In this thesis work, we have utilized near-infrared (NIR) light to investigate the feasibility of optical wireless data transfer through biological tissues. To understand the basics of optical communications through biological tissues (OCBT), fresh meat samples and optical phantoms have been used as models of living biological tissues. An experimental testbed containing a data modulated light source and a photodetector was implemented to carry out different measurements regarding the OCBT concept. We have explored the influence of parameters like transmitted optical power, temperature of the tissue, tissue thickness, and position of the light source on the performance of the light-based through-tissue communication system. Analysis of the measurement data allowed us to compare and characterize the effect of used optical elements for better performance evaluation of the optical communication system. We have successfully transmitted a high-resolution image file through a 3 cm thick pork tissue sample. The maximum transmitted power through the tissue sample during the optical communication was 231.4 mW/cm2, which is well below the limits defined by standard of safety regulation. A data rate of 22 kilobits per second has been achieved with the experimental system. Practical limitations of the current testbed prevented obtaining a higher data throughput. The results indicate a dependence of optical received power with respect to the tissue temperature. Moreover, we found both thickness and compositional differences of the biological tissues have a significant impact on the transmittance rate. This thesis work can be considered as a part of the development of 6G technology. The outcomes of this pilot study are very promising, and in the future, numerous potential applications based on OCBT could be developed, including wireless communications to implanted devices, in-body sensors, smart pills, and others.

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Copyright information: © Senjuti Halder, 2020. This publication is copyrighted. You may download, display and print it for your own personal use. Commercial use is prohibited.