A systematic review on the detection and monitoring of toxic gases using carbon nanotube-based biosensors

Environmental detection, monitoring and controlling of pathogenic or harmful gases has become an utmost priority. They contribute to major public health problems such as respiratory diseases, cardiovascular dysfunction and diseases, central nervous system (CNS) anomalies and other diseases (cancer, bronchiolitis, asthma etc.). Also, they are associated with frightening global warming thus affecting the ambient environment. Therefore, there is an urgent need to control and mitigate these gases. Notably, the existing conventional gas sensors are painstakingly very slow, labour and capital intensive, invasive and require specialized apparatuses and human capital to operate. A glowing need to develop cheap, fast, efficient, highly sensitive, portable sensors with less power usage and a high degree of reliability has been on the rise. Carbon nanotubes (CNTs) have been extensively explored to develop biosensors owing to fact that they are tubular-nanosized materials with excellent biocompatibility coupled with large surface area, excellent thermal, electrical, mechanical and optical properties. In the recent past, the invention and fabrication of CNTs-based biosensors and their mechanisms have been a subject of intense research studies in the detection and monitoring of gases. Therefore, in this short review, we present an in-depth overview survey of CNTs-based biosensors for gas sensing sourced from published papers and online articles. The paper also highlights challenges associated with CNTs-based gas sensors, possible remedial actions and future work opportunities in this research area.