# Capabilities of Human Biotissue Fluorescence Spectroscopy in the Wearable Multimodal Version

## TL;DR

This paper explores how wearable fluorescence spectroscopy can detect metabolic changes in biotissues, offering new diagnostic possibilities in practical medicine.

## Contribution

The study introduces a wearable multimodal device combining fluorescence spectroscopy and laser Doppler flowmetry for biotissue analysis.

## Key findings

- Fluorescence intensity changes reflect biotissue metabolic processes despite melanin and hyperemia effects.
- A wearable multimodal system can measure skin fluorescence spectra across a wide range (320-900 nm).
- The device shows potential as a diagnostic tool for oxidative metabolism in practical medical settings.

## Abstract

Pathological processes in biotissues are characterized by a shift in metabolic homeostasis causing biochemical changes, which can be detected by fluorescence spectroscopy methods. A wide spectrum of capabilities, simple implementation, and valuable diagnostic information obtained attract considerable interest of the medical community.

The aim of the study is to analyze the current problems of fluorescence spectroscopy of biotissues and demonstrate new capabilities of this method in a wearable multimodal version for solving various problems of practical medicine.

Factors influencing the registration of biotissue fluorescence have been considered. It has been established that the assessment of mitochondrial function (oxidative metabolism) by NADH and FAD fluorescence spectra is possible only under certain assumptions due to the difficulties in determining the contribution of collagen and some other fluorophores to the total spectrum. The capabilities of multimodal approach have been studied, i.e. сombining fluorescence spectroscopy and laser Doppler flowmetry in one diagnostic system as a wearable version of device implementation.

To demonstrate the capabilities of the wearable analyzers of the oxidative biotissue metabolism, pilot experimental investigations have been carried out involving 8 conditionally healthy volunteers. Parameters of microcirculatory-tissue systems (oxidative metabolism) were recorded with a modified multimodal wearable analyzer capable of measuring the skin fluorescence spectra in a wide range from 320 to 900 nm. Skin fluorescence was registered in the region of forehead, dorsal carpal surface, the volar surface of the distal phalanx of the middle finger, and the plantar surface of the distal phalanx of the first toe at a 365 nm wavelength of exciting irradiation.

The conducted experiment has shown that despite the existing effect of biotissue hyperemia together with the level of melanin on the recorded fluorescence spectrum, the assessment of skin fluorescence intensity in dynamics and functional tests reflect changes in metabolic processes of biotissues and may be considered as a promising diagnostic criterion.