Abstract With the rapid growth of cities, new problems and challenges have appeared; transportation, communication technology, structural health-care services, industry, education, and many more are used to enhance the quality of life of citizens that live in a “smart city.” Structural health monitoring (SHM) represents a great engineering challenge for providing information in real time and data collection of big data with the help of Internet of Things systems to connect everything in cities. In this chapter, an optical scanning system (OSS) for monitoring the structure’s health is proposed. The OSS operating principle is based on the sensing of a light indicator with a wavelength of 420 nm and the application of digital filters to smooth the electric noise and effects caused by environmental conditions. By using a blue light emitting diode as a photosensor in conjunction with digital filters, such as Savitzky–Golay and moving average, the signal with noise captured from photosensors was smoothed, improving the measurement accuracy of the OSS dedicated to SHM. This chapter also describes different devices and methods used for smart applications based on SHM with signals in the scale of nanometers.