Multimodal optical analysis of human skin

Validation of new methods for biomedical imaging and analysis is often based on simplified model samples of the target tissue. These tissue phantoms should have defined, reliable and reproducible characteristics close to the tissue and desirably are simple enough to be used for simulations in order to adapt and optimize the measurement system. For multimodal approaches, various demands on tissue phantoms have to be met in order to satisfy the needs of all modalities. We present and discuss a hydrogel phantom that was created for combined Raman spectroscopic and optoacoustic measurements imposing optical as well as acoustic requirements on the phantom. In this phantom, defined concentrations of carotenes should be available in an optically scattering and absorbing matrix to test and validate the capability of this combination of methods to quantify specific biomolecules in human skin. We will show that solvent effects play a major role for both absorption spectra and Raman resonance profiles and need to be considered with great care if a tissue phantom really is to mimic the true biomedical model.