Katika Kamal M, Pilon Laurent
Mechanical and Aerospace Engineering Department, Henry Samueli School of Engineering and Applied Science, University of California, Los Angeles, California 90095, USA.
Appl Opt. 2007 Jun 1;46(16):3359-68. doi: 10.1364/ao.46.003359.
The goal of this study is to test the feasibility of using an embedded time-resolved fluorescence sensor for monitoring glucose concentration. Skin is modeled as a multilayer medium with each layer having its own optical properties and fluorophore absorption coefficients, lifetimes, and quantum yields obtained from the literature. It is assumed that the two main fluorophores contributing to the fluorescence at these excitation and emission wavelengths are nicotinamide adenine dinucleotide (NAD)H and collagen. The intensity distributions of excitation and fluorescent light in skin are determined by solving the transient radiative transfer equation by using the modified method of characteristics. The fluorophore lifetimes are then recovered from the simulated fluorescence decays and compared with the actual lifetimes used in the simulations. Furthermore, the effect of adding Poissonian noise to the simulated decays on recovering the lifetimes was studied. For all cases, it was found that the fluorescence lifetime of NADH could not be recovered because of its negligible contribution to the overall fluorescence signal. The other lifetimes could be recovered to within 1.3% of input values. Finally, the glucose concentrations within the skin were recovered to within 13.5% of their actual values, indicating a possibility of measuring glucose concentrations by using a time-resolved fluorescence sensor.
本研究的目标是测试使用嵌入式时间分辨荧光传感器监测葡萄糖浓度的可行性。皮肤被建模为多层介质，各层具有从文献中获取的自身光学特性、荧光团吸收系数、寿命和量子产率。假设在这些激发和发射波长下对荧光有贡献的两个主要荧光团是烟酰胺腺嘌呤二核苷酸（NAD）H和胶原蛋白。通过使用改进的特征线法求解瞬态辐射传输方程，确定皮肤中激发光和荧光的强度分布。然后从模拟的荧光衰减中恢复荧光团寿命，并与模拟中使用的实际寿命进行比较。此外，还研究了在模拟衰减中添加泊松噪声对寿命恢复的影响。在所有情况下，发现由于NADH对整体荧光信号的贡献可忽略不计，其荧光寿命无法恢复。其他寿命可恢复到输入值的1.3%以内。最后，皮肤内的葡萄糖浓度恢复到其实际值的13.5%以内，这表明使用时间分辨荧光传感器测量葡萄糖浓度具有可能性。
