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Doctoral defence of Shekh Emran, MSc, 27.1.2023: Novel bioimpedance spectroscopic methods for examination of oral mucosal tissues

The doctoral dissertation in the field of Applied Physics will be examined at the Faculty of Science, Forestry and Technology, Kuopio Campus and online.

What is the topic of your doctoral research? Why is it important to study the topic?

Many oral cancers are preceded by oral potentially malignant disorders (OPMDs), a group of oral mucosal diseases that include e.g., oral leukoplakia, oral erythroplakia, and oral lichen planus. The diagnosis of these diseases is based on the histological examination of surgically removed biopsies.  However, it is a painful and expensive method to confirm a diagnosis and is not feasible for routine follow-up monitoring. Therefore, there is a clear clinical need for a rapid and painless method for regular assessment of the health condition of the oral mucosa.

The purpose of this Ph.D. study is to develop new Bioimpedance Spectroscopy (BIS) based measurement and analysis techniques for the next-generation assessment of oral mucosal health. 3D-printed probes developed in this thesis can be applied not only to oral tissues but also to other biological tissues. The results of this study are innovative and significant in developing next-generation objective solutions for the early-phase detection of pathological tissue changes and related pain conditions in vivo.

What are the key findings or observations of your doctoral research?

In order to minimize the artifacts and maximize the reproducibility of the measurement, we found that it was necessary to maintain a fixed load on the concentric probe (2-terminal) in order to achieve good, stablecontact with the tissue samples. However, in four-terminal measurements with small and medium size probes, we found that changes in the loading weight did not affect the results obtained since contact impedance waseliminated with this measurement configuration. Moreover, it was challenging to select the optimal electrode material for 3D-printed probes in order to avoid electrochemical corrosion problems and other signal instabilities. While conducting ex-vivo tissue measurements, a general trend of decreasing impedance magnitude with increasing frequency was observed, with a unique characteristic spectrum of each tissue type. On the other hand, the literature survey conducted in this thesis showed that a 50 kHz frequency could be ideal for discriminating between healthy and cancerous tissue.

What are the key research methods and materials used in your doctoral research?

In this thesis, different probes were designed, developed, and tested for BIS measurement in aiming to clarify some of the fundamental methodological issues in gathering reliable BIS measurements and evaluating the technique’s potential in the early, non-invasive detection of oral mucosal diseases. Three differently fabricated probes namely a custom-made concentric ring probe, a novel 3D printing-based probe and fully 3D printed probes in three different sizes were realized and tested over a wide frequency range (1 Hz – 3 MHz). All probes were systematically tested with phantom materials prior to the investigations with ex-vivo tissue samples. Moreover, the shortcomings of the current diagnostic procedure of OPMDs, and the status of the BIS technique in the assessment of oral mucosal health were evaluated in a literature review.

The doctoral dissertation of Shekh Emran, MSc, entitled Novel bioimpedance spectroscopic methods for examination of oral mucosal tissues will be examined at the Faculty of Science, Forestry and Technology, Kuopio Campus and online. The opponent will be Adjunct Professor Harri Sievänen, Injeq Plc,  and the custos will be Adjunct Professor Sami Myllymaa, University of Eastern Finland. Language of the public defence is English.

For more information, please contact:

Shekh Emran,, tel. +358 509 119 062