Lighting Up the Oceans—Real-Time, Multi-Omic Ocean Observation with High-Quality-Factor Metasurfaces

Phytoplankton are microscopic organisms responsible for half of the global photosynthetic carbon fixation and at least half of the world’s oxygen production. The changing climate is driving fundamental shifts in phytoplankton nutrient cycling, with profound impact on marine and freshwater ecosystems. For example, certain phytoplankton taxa can produce powerful biotoxins that harm humans and wildlife, contaminate water sources, and damage local economies, leading the National Academies to call for the development of <i>in situ</i> sensors of phytoplankton nutrient cycling as critical infrastructure needed to advance climate resilience. Predominant methods of studying phytoplankton toxins and their genes are based on tandem mass spectrometry (LC/MS-MS), the polymerase chain reaction (PCR), and DNA/RNA sequencing. These methods are costly, require sophisticated infrastructure, and lack remote, autonomous, real-time detection capabilities that are central to time-series measurements necessary to understand coupled hydrography and climate/ecosystem dynamics.<br/> <br/>Here, we present a metasurface-based technology to simultaneously and rapidly measure multiple ‘omic’ signatures of phytoplankton from aquatic samples. Our high-quality-factor (“high-Q”) dielectric metasurfaces produce a large amplification of the electromagnetic field intensity, increasing the response to minute refractive index changes from target binding; simultaneously, the light is beam-steered to particular detector pixels. By combining metasurface design with acoustic bioprinting of samples, we produce microarrays of densely packed sensing pixels, each functionalized with distinct molecular recognition elements. On the same metasurface, we demonstrate specific detection of gene fragments, proteins, and small molecule toxins across hundreds of individual resonators simultaneously. We describe application of this quantitative assay to in-situ molecular analysis of environmental DNA, domoic acid, and microcystin. Finally, we discuss integration of our high-Q metasurfaces with the Environmental Sample Processor, an autonomous robotic water sampler developed at the Monterey Bay Aquarium Research Institute (MBARI), that offers a pathway for in situ phycotoxin detection, processing, and analysis.