The dyes produced by the textile industry have been identified as pollutants that contribute to the discoloration of wastewater and pose significant environmental challenges. Nanotechnology, a rapidly advancing field of research, is actively exploring the development of Nano sensors for various applications, including the detection of different types of azo-toxic dyes in food products. This advancement holds promising potential for the future, as novel Nano sensor designs continue to emerge. The present article provides recent insights into various types of Nano sensors and their pivotal role in sensing applications. Specifically, it focuses on the detection of azo toxic dyes (e.g.methylene blue dye) using Nano sensors, highlighting their advantages compared to other sensor technologies. One notable technique for determining dye concentrations is the Quartz Crystal Microbalance (QCM), which utilizes the high sensitivity of resonant crystal frequency. Experimental results demonstrate that the QCM method is capable of providing real-time, accurate quantitative and qualitative analysis of dyes in wastewater . Furthermore, a novel copper-based Nano sensor has been developed for the comparable detection of Methylene Blue (MB). The characterization of this Nano copper complex was conducted using various analytical tools, including Dynamic Light Scattering (DLS), Zeta potential analysis, Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), Fourier Transform Infrared Spectroscopy (FT-IR), and BET surface area and pore size determination. The lipophilicity of the applied ionophore was investigated through the contact angle measurement technique, and the average contact angle was found to be 121.59°, indicating the sensor's mechanical stability. The effect of different pH and temperature on the sensor's performance was also monitored. The proposed sensor demonstrated a rapid response time of 3 minutes and exhibited a reliable response even at very low dye concentrations, as low as 1 ppm.