Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Ciudad de México, México.
Food Technology Department, Universitat Politècnica de València, Valencia, Spain.
Comput Methods Programs Biomed. 2022 Jun;221:106896. doi: 10.1016/j.cmpb.2022.106896. Epub 2022 May 16.
In the last few years, we have been exploring the use of transparent nanocrystalline yttria-stabilized zirconia (nc-YSZ) ceramics as a biomedical transparent cranial implant, referred as the "Window to the Brain" (WttB). The WttB aims at providing chronical optical access to the brain for diagnostics and therapeutic procedures and it has shown to provide an effective means to obtain enhanced results from optical imaging techniques. The objective of this work is to explore the photothermal effects of the Wttb produced when it is irradiated by a laser source.
We make experimental and computer models. The thermal effects of laser irradiation on the nc-YSZ samples were evaluated upon registering the induced temperature changes by means of thermal imaging. The computer models try to mimic the experimental models using a similar geometry, reproducing the physical situation by a couple thermal-optical problem and adjusting the main parameters from the experimental results.
Experimental and computational coincides in results: Temperatures at the bottom surface of the implant does not exceed those which produce thermal damage. The quantitative comparison between experimental and computational models show that differences in results are under a reasonable value of 5% and qualitatively we observe a similar behavior. The results provide optimum values for the thermal-optical nc-YSZ parameters considering a linear and exponential relationship with temperature for the absorption coefficient: The thermal conductivity is k = 2.13 W/m·K and the absorption coefficient α varies from 426 to 526 m with the linear relationship, and k = 2.04 W/m·K and α ∈ [433,502] m with the exponential. The reflection coefficient is R = 19% in both cases.
The temperatures achieved in the nc-YSZ during the laser irradiation are suitable for biomedical applications. The combination of experimental and computational models contributes to build a clinically oriented model with the thermal-optical parameters values stablished and to determine their influence in results. Specifically, the absorption coefficient of the nc-YSZ samples is the most influent parameter in the obtained temperatures. Moreover, this combination provides a method to evaluate the relevant thermal-optical parameters of nc-YSZ samples obtained with different manufacturing processes.
在过去的几年中，我们一直在探索使用透明纳米晶氧化钇稳定氧化锆（nc-YSZ）陶瓷作为生物医学透明颅植入物，称为“大脑之窗”（WttB）。WttB 的目的是为了提供对大脑的慢性光学通道，用于诊断和治疗程序，并且已经表明它是一种从光学成像技术中获得增强效果的有效方法。这项工作的目的是探索当 WttB 被激光源照射时产生的光热效应。
我们进行了实验和计算机建模。通过热成像记录激光照射引起的温度变化，评估了激光照射对 nc-YSZ 样品的热效应。计算机模型通过几个热光学问题来模拟实验模型，通过调整主要参数来自实验结果，从而再现物理情况。
实验和计算结果相符：植入物底部表面的温度不超过产生热损伤的温度。实验和计算模型之间的定量比较表明，结果之间的差异在合理的 5%范围内，并且定性地我们观察到相似的行为。结果提供了最佳的热光 nc-YSZ 参数值，考虑到吸收系数与温度的线性和指数关系：热导率 k=2.13 W/m·K，吸收系数α在 426 到 526 m 之间与线性关系，k=2.04 W/m·K，α∈[433,502] m 与指数关系。在这两种情况下，反射系数 R=19%。
在激光照射期间，nc-YSZ 中达到的温度适用于生物医学应用。实验和计算模型的结合有助于建立一个具有临床导向的模型，确定其热光参数值，并确定它们对结果的影响。具体来说，nc-YSZ 样品的吸收系数是获得温度的最主要参数。此外，这种组合提供了一种方法来评估具有不同制造工艺的 nc-YSZ 样品的相关热光参数。
