Monitoring the refractive index of tissue models using light scattering spectroscopy

TL;DR

This study demonstrates the use of Raman microspectroscopy to accurately measure the refractive index of tissue phantoms, offering a non-invasive alternative to traditional refractometry methods.

Contribution

It introduces a calibration-based Raman spectroscopy method for determining tissue phantom refractive indices, combining optical and spectroscopic techniques.

Findings

Raman spectra can be used to determine refractive index with similar accuracy to refractometry.

A calibration curve correlates Raman intensity with refractive index for tissue phantoms.

The method enables non-invasive, spectroscopic analysis of tissue optical properties.

Abstract

In this work, we report the application of Raman microspectroscopy for analysis of the refractive index of a range of tissue phantoms. Using both a custom-developed setup with visible laser source and a commercial micro-spectrometer with near infrared laser, we measured the Raman spectra of gelatin hydrogels at various concentrations. By building a calibration curve from measured refractometry data and Raman scattering intensity for different vibrational modes of the hydrogel, we determined the refractive indices of the gels from their Raman spectra, with approximately the same accuracy as that of refractometry measurements with an Abbe refractometer. This work highlights the importance of a correlative approach through Brillouin-Raman microspectroscopy for the mechano-chemical analysis of biologically relevant samples.