Bionanosensors and nanosensors have been devised in recent years with the use of various materials including carbon-based nanomaterials,for applications in diagnostics,environmental science and microelectronics.Carbon-based materials are critical for sensing applications,as they have physical and electronic properties which facilitate the detection of substances in solutions,gaseous compounds and pollutants through their conductive properties and resonance-frequency transmission capacities.In this review,a series of recent studies of carbon nanotubes(CNTs) based nanosensors and optical systems are reported,with emphasis on biochemical,chemical and environmental detection.This study also encompasses a background and description of the various properties of the nanomaterials,and the operation mechanism of the manufactured nanosensors.The use of computational chemistry is applied in describing the electronic properties and molecular events of the included nanomaterials during operation.This review shows that resonance-based sensing technologies reach detection limits for gases,such as ammonia down to 10~(-24) level.The study also shows that the properties of the carbon nanomaterials give them unique features that are critical for designing new sensors based on electrocatalysis and other reactive detection mechanisms.Several research fields can benefit from the described emerging technologies,such as areas of research in environmental monitoring,rapid-on site diagnostics,in situ analyses,and blood and urine sampling in medical and sport industry.Carbon nanomaterials are critical for the operational sensitivity of nanosensors.Considering the low cost of fabrication,carbon nanomaterials can represent an essential step in the manufacturing of tomorrow’s commercial sensors. Bionanosensors and nanosensors have been devised in recent years with the use of various materials including carbon-based nanomaterials, for applications in diagnostics, environmental science and microelectronics. Carbon-based materials are critical for sensing applications, as they have physical and electronic properties. the detection of substances in solutions, gaseous compounds and pollutants through their conductive properties and resonance-frequency transmission capacities. In this review, a series of recent studies of carbon nanotubes (CNTs) based nanosensors and optical systems are reported, with emphasis on biochemical, chemical and environmental detection. This study also contains a background and description of the various properties of the nanomaterials, and the operation mechanism of the manufactured nanosensors. The use of computational chemistry is applied in describing the electronic properties and molecular events of the included nanomaterials during operation.Th is review shows that resonance-based sensing technologies reach detection limits for gases, such as ammonia down to 10 ~ (-24) level. The study also shows that the properties of the carbon nanomaterials give them unique features that are critical for designing new sensors based on electrocatalysis and other reactive detection mechanisms .Several research fields can benefit from the described emerging technologies, such as areas of research in environmental monitoring, rapid-on site diagnostics, in situ analyzes, and blood and urine sampling in medical and sport industry. Carbon nanomaterials are critical for the operational sensitivity of nanosensors. Consumption of the low cost of fabrication, carbon nanomaterials can represent an essential step in the manufacturing of tomorrow’s commercial sensors.