The ultra-low detection of substances of interest in atto-molar concentration ranges can be exploited to detect the analyte in real-world scenarios via simple dilution steps. The high sensitivity of several plasmonic-based biosensors is utilized to detect biomarkers or pollutants at an atto-molar level. This goal can be achieved via low-cost and simple equipment in small-sized setups combined with sensor chips based on ultra-high-sensitive plasmonic probes or ultra-efficient receptor layers. More specifically, extrinsic and intrinsic optical fiber sensing schemes can be achieved using plastic optical fiber (POF) characteristics combined with cheap equipment. The reported sensing strategy is simply implemented using a white light source and spectrometers. For instance, this work recalls atto-plasmonic sensors achieved via hybrid plasmonic probes combined with several receptors or ultra-efficient receptors and integrated into conventional plasmonic probes. These atto-plasmonic sensors, which utilize simple setups, can be useful for detecting substances of interest via Point-of-Care Tests (PoCTs) in various application fields. The sensor systems enable on-site measurement of the substance of interest in just a few minutes, with the results transmitted via an Internet connection. Moreover, via the Internet connection, remote control of sensor systems for on-site measurement can be carried out, combining the sensors with mechatronics and robotics.