接触压力作用下皮肤形变对于漫反射光谱测量影响研究

人体成分无创光谱检测过程中，测量条件特别是探头压力造成的组织形变在一定程度上影响光谱测量结果。利用物理模型与仿真方法，定量分析了探头接触压力作用下皮肤组织应变，及光学参数与漫反射光谱变化。首先，在多层皮肤组织物理复合模型基础上，结合生物组织固液两相组成特性，定量分析了压力作用下各层皮肤组织形变大小以及成分变化。该模型将皮肤力学模型简化为固态弹性结构及包含于其中的牛顿流体，利用有限元方法，分别模拟不同压力作用下多层皮肤组织应变大小及时间特性，并根据各层组织体积及水含量变化，定量计算其散射系数及吸收系数改变。然后，利用Monte Carlo方法模拟压力作用前后光在组织中传输过程，定量分析了探头压力对漫反射光谱中所包含人体成分检测有效信息的影响。实验结果表明，在光纤探头接触压力作用下，人体皮肤组织中真皮层厚度变小，自由水体积减小，引起散射特性及光子传输路径改变，使得漫反射光谱中所包含的有效光谱信息下降。该研究结果为优化人体漫反射光谱测量策略，提高测量准确性以及重复性提供了参考。

Research on the Influence of Pressure-Induced Skin Deformation on the Diffuse Reflectance Spectra Measurement

In the non-invasive tissue composition detecting,the diffuse reflectance spectroscopy could be affected by the measure-ment conditions,especially the tissue deformation induced by the contact pressure.In this paper,the physical model was simula-ted to quantify the changes of tissue thickness,optical properties and diffuse reflectance induced by the contact pressure,respec-tively.Firstly,based on the physical complex model and solid-liquid mixture composition of biological tissue,the deformation and changes of the water under contact pressure were quantitatively analyzed.In this model,the skin tissue was modeled as the elastic structure filled with Newtonian fluid.Then,the finite element method was applied to simulate the time-varying deforma-tion of tissue under certain contact pressure.Secondly,the scattering and absorption coefficients of tissue were calculated with the quantitative results of the deformation and water migration in the three-layered skin tissue.After that,Monte Carlo method was used to simulate the light propagation within the tissue under different pressures.Finally,the effective information con-tained in the diffuse reflectance spectrum was analyzed to quantify the influence of the contact pressure.The results showed that the reduction of thickness and water content in dermis resulted in the decrease of effective information contained in the diffuse re-flectance spectrum.The conclusions of this paper are beneficial for optimizing measurement strategy and improving accuracy and repeatability of the in vivo diffuse spectroscopy measurements.