This Special Issue aims to collect and present cutting-edge research on all plasmonic sensor technologies to contribute to the research, design, development, and applications with articles that demonstrate the most recent advances in plasmonic sensors with new scientific knowledge, designs, and their practical applications. A total of seven papers in various fields of SPR sensors are presented in this Special Issue. In the article by [PERSON] et al. [14] a Tunable plasmonic resonance sensor using a metamaterial film on a D-shaped photonic crystal fiber for refractive index measurements is proposed. These meta-materials are sub-wavelength cells of metallic nanorods arranged in a dielectric background, and exhibit bulk properties that are useful for controlling and manipulating surface plasmon resonances. [PERSON] et al. [11] present the design of two sensors, one for the continuous measurement of sucrose concentration with sensitivities of 11.9-5.7 RIU\({}^{-1}\) and resolutions of the order of \(10^{-4}\) RIU; this sensor is capable of measuring sucrose concentrations of up to 78 BRIX, that no plasmonic sensor has so far been capable of measuring. The other sensor [15] measures CO\({}_{2}\) concentrations with a resolution of \(10^{-5}\) RIU. This new sensor, due to its sensitivity and resolution, along with its diminutive size, could be integrated into an electronic nose and used on spacecraft, the International Space Station, or even commercial flights. Both sensors have some of the highest sensitivities and resolutions to date in this type of plasmonic sensor. An important fact about SPR sensors is how temperature affects the measurements. Temperature changes the wavelength at which surface plasmon resonance occurs. On the other hand, it is evident that an increase or decrease in temperature affects the propagation of radiation in optical fibers. The study by [PERSON] et al. [16] shows a novel dual wavelength method to evaluate the effect of temperature on fiber optic SPR sensors in real time. As an example of a sensor used in medicine, we have the sensor by [PERSON] et al. [17]. These researchers have applied plasmon biosensors based on surface plasmon resonance imaging (SPRi) to detect the 20S proteasome protein and ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) in the blood serum and urine of patients with TCC (narrow cell carcinoma) of transition and to be able to make an early diagnosis of bladder cancer. The contamination of phenolic compounds in the natural environment is a toxic response that induces severe impact on plants, animals, and human health. [PERSON], [PERSON] et al. [18] have made an updated review of the recent developments and trends of new plasmon resonance nanomaterials, which are assisted by various optical sensors, including colorimetry, fluorescence, localized surface plasmon resonance (LSPR), and plasmon-enhanced Raman spectroscopy. These advanced and powerful analytical tools exhibit potential application for ultra-high sensitivity, selectivity, and rapid detection of phenol and its derivatives. The article by [PERSON] et al. [19] presents an exhaustive review of gas sensors based on the localized surface plasmon resonance (LSPR) phenomenon, including LSPR theory, the synthesis of nanoparticle-embedded oxide thin films, and strategies to improve the sensitivity of these optical sensors, supported by simulations of electromagnetic properties. The submission for this Special Issue is now closed, but the SPR sensors are still current, research does not stop and technology takes advantage of all the scientific advances on new materials and plasmons to face the new challenges that science, technology and society, demand. We are continuing to work on this. This research received no external funding. Thanks to all the authors and peer reviewers for their valuable contributions to this Special Issue 'Optical sensors and gauges based on plasmonic resonance'. I would also like to express my gratitude to all the staff and people involved in this Special Issue.