High-throughput corrosion quantification in varied microenvironments

Harsh conditions ranging from those of biomedical implants to industrial oilfield applications prompt rapid assessment of whether and to what extent corrosion will occur. Here, we describe and demonstrate a novel high-throughput approach to quantify corrosion susceptibility based upon electrical resistance and colorimetric outputs. We illustrate this capability by quantifying aerobic corrosion rates of steel alloys within hours, and by comparing anaerobic microbiologically influenced corrosion (MIC) conditions over several days. Such methods can be extended to rapidly assess conditions that will accelerate corrosion , to compare corrosion mitigation scenarios, and to explore biofilm formation and MIC mechanisms through robust replicate conditions. As technological advancement enables us to access increasingly harsh environments, ranging from implanted biomedical devices to undersea oil and gas deposits, we continue to test the limits of corrosion susceptibility and require quantitative insights to predict and extend structural reliability. The highly complex nature of corrosion processes, as well as the wide range of relevant environmental variables , complicates rigorous identification of corrosion susceptibility. For example, despite mitigation attempts, microbiologically-influenced corrosion (MIC) and associated biofilm formation (biofouling) have been implicated in several rapidly progressing, high-profile failures of buried steel pipeline [1–4]. While sulfate reducing bacteria (SRB) are considered a main culprit in anaerobic environments, the complex consortium of microbial species and the biofilms they produce have obviated mechanistic conclusions. Despite much research of the microbiology and the engineering effects, the mechanisms by which MIC enhances ferrous corrosion and the appropriate strategies to mitigate MIC corrosive loss remain elusive [5,6]. The limitations of prevailing experimental techniques to quantify and predict corrosion in controlled environments have led to the development of several higher-throughput measurement methods (see two recent review articles [7,8]). Current high-throughput approaches use either a single metal bulk substrate with areas controllably exposed to different microenvironments [9,10], deposited metallic thin films in each microenvironment [11–13], or multiple electrode systems (2 or 3) within each micro-environment [14–18]. While existing high-throughput methods hold tremendous promise in certain conditions, their production is not necessarily straightforward and scalable, and their applicability for biotic studies which require complete isolation between microenvironments to prevent cross-contamination and a continuous surface for bacterial colonization is unclear. Here we describe a high-throughput corrosion testing platform that assays corrosion susceptibility of metals by tracking the changing resistance of thin wires and colorimetric changes of the surrounding solution within a 96-well format. While resistance-based probes have been validated as an …