Department of Bioengineering, University of California, Berkeley, Berkeley, California, United States of America.
University of California, Berkeley-University of California, San Francisco Graduate Program in Bioengineering, Berkeley, California, United States of America.
PLoS One. 2021 Jan 6;16(1):e0243554. doi: 10.1371/journal.pone.0243554. eCollection 2021.
With COVID-19 N95 shortages, frontline medical personnel are forced to reuse this disposable-but sophisticated-multilayer respirator. Widely used to decontaminate nonporous surfaces, UV-C light has demonstrated germicidal efficacy on porous, non-planar N95 respirators when all surfaces receive ≥1.0 J/cm2 dose. Of utmost importance across disciplines, translation of empirical evidence to implementation relies upon UV-C measurements frequently confounded by radiometer complexities. To enable rigorous on-respirator measurements, we introduce a photochromic indicator dose quantification technique for: (1) UV-C treatment design and (2) in-process UV-C dose validation. While addressing outstanding indicator limitations of qualitative readout and insufficient dynamic range, our methodology establishes that color-changing dosimetry can achieve the necessary accuracy (>90%), uncertainty (<10%), and UV-C specificity (>95%) required for UV-C dose measurements. In a measurement infeasible with radiometers, we observe a striking ~20× dose variation over N95s within one decontamination system. Furthermore, we adapt consumer electronics for accessible quantitative readout and use optical attenuators to extend indicator dynamic range >10× to quantify doses relevant for N95 decontamination. By transforming photochromic indicators into quantitative dosimeters, we illuminate critical considerations for both photochromic indicators themselves and UV-C decontamination processes.
由于 COVID-19 导致 N95 口罩短缺，一线医护人员被迫重复使用这种一次性但结构复杂的多层呼吸器。紫外线-C 光已被广泛用于对非多孔表面进行消毒，当所有表面都接受≥1.0 J/cm2 的剂量时，它对多孔、非平面的 N95 呼吸器具有杀菌功效。在各个学科中最重要的是，将经验证据转化为实施依赖于紫外线-C 测量，而这些测量经常受到辐射计复杂性的干扰。为了能够在呼吸器上进行严格的测量，我们引入了一种光致变色指示剂剂量量化技术，用于：（1）紫外线-C 处理设计，（2）过程中的紫外线-C 剂量验证。在解决指示剂定性读数和动态范围不足的突出问题的同时，我们的方法表明，变色剂量测定法可以达到紫外线-C 剂量测量所需的必要准确性（>90%）、不确定性（<10%）和紫外线-C 特异性（>95%）。在辐射计无法进行测量的情况下，我们观察到在一个消毒系统内，N95 口罩之间的剂量差异惊人地达到了~20 倍。此外，我们还采用了消费电子产品进行可访问的定量读数，并使用光学衰减器将指示剂的动态范围扩展>10 倍，以量化与 N95 消毒相关的剂量。通过将光致变色指示剂转化为定量剂量计，我们阐明了光致变色指示剂本身和紫外线-C 消毒过程都需要考虑的关键问题。
