Chemical sensing as a utility using parallel, distributed swept source Raman spectroscopy

Today, molecular analysis at multiple locations requires either transporting samples to a central laboratory via transportation or conveyor networks or deploying independent analyzers at each sampling point. Neither of these approaches offers the accessibility and scalability we have come to expect from modern utility infrastructure that provides access to water, electricity, information (internet), and computation resources. Here, we demonstrate a novel parallel, distributed, optical fiber swept-source Raman spectroscopy approach that replaces spectrometers with compact semiconductor tunable lasers along with high-collection power fiber-optic probes and sensitive single photon avalanche detectors (SPAD) photodetectors. Fiber probes with 12x higher light collection power than benchtop spectrometers are integrated with compact detection hardware, allowing us to realize a scalable network of Raman sensors distributed over 16 locations at distances of 100 m. This network shares essential resources, such as the tunable laser, and leverages existing infrastructure networks, such as communication optical fiber and computation hardware. We illustrate the capabilities of this network with an industrial monitoring application, where we monitor therapeutic monoclonal antibody production in a CHO cell culture, and an environmental monitoring application, where we monitor nitrogen fertilizer in hydroponic agriculture.