Rapid industrial growth has severely impacted ecosystems and aggravated economic and health risks to society. Monitoring of ecosystems is fundamental to our understanding of how ecosystem change impacts resources and is critical for developing data-based sustainability. Thus, the design and development of optimized sensors for ecosystem monitoring have received increasing attention.This review provides a comprehensive overview of systematic sensor design strategies for ecosystem monitoring from the material level to the form factor level. We discuss the fundamental transducing mechanisms of a representative sensor system including optical, electrical, and electrochemical sensors. We then review the sensor interfacing strategy for achieving stable and real-time monitoring of environmental biochemical factors from air, water, soil, and living organisms. Finally, we provide a summary of the current performance and prospects of this state-of-the-art sensor technology and an outlook on opportunities for possible future research directions in this emerging field.
Accurate, onsite detection of pathogenic bacteria from food matrices is required to rapidly respond to pathogen outbreaks. However, accurately detecting whole-cell bacteria in large sample volumes without an enrichment step remains a challenge. Therefore, bacterial samples must be concentrated, identified, and quantified. We developed a tunable magnetic capturing cartridge (TMCC) and combined it with a portable digital fluorescence reader for quick, onsite, quantitative detection of Staphylococcus aureus. The TMCC platform integrates an absorption pad impregnated with water-soluble polyvinyl alcohol (PVA) with an injection-molded polycarbonate (PC) plate that has a hard magnet on its back and an acrylonitrile-butadiene-styrene case. An S. aureus-specific antibody conjugated with magnetic nanoparticles was used to concentrate bacteria from a large-volume sample and capture bacteria within the TMCC. The retention time for capturing bacteria on the TMCC was adjusted by controlling the concentration and volume of the PVA solution. Concentrated bacterial samples bound to target-specific aptamer probes conjugated with quantum dots were loaded into the TMCC for a controlled time, followed by attachment of the bacteria to the PC plate and removal of unbound aptamer probes with wash buffer. The captured bacteria were quantified using a digital fluorescence reader equipped with an embedded program that automatically counts fluorescently tagged bacteria. The bacterial count made using the TMCC was comparable to a standard plate count (R 2 = 0.9898), with assay sensitivity and specificity of 94.3 and 100%, respectively.
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