Smart Sensors for Monitoring pH, Dissolved Oxygen, Electrical Conductivity, and Temperature in Water

Water is a crucial resource that sustains life and it exists in liquid form only on planet Earth. Challenges pertaining to global environmental pollution put water at the forefront of the resources to be protected, conserved, and remediated. Real‐time and wireless water quality sensors help to continuously monitor and detect abnormal chemical, physical, and biological activities and act as early warning systems for responsible authorities. Traditionally used sensors are bulky, require wet storage, and have limited possibilities of miniaturization. Moreover, laboratory‐based water quality testing requires transportation of samples which is time‐consuming, costly, and leads to altered results. Smart sensors help us to overcome those technical and practical obstacles. Materials and design of the sensor play a key role in its performance and scientific research has paved the way for a new class of semiconductor‐based sensors using metal oxides and other new materials. They provide advantages like miniaturization, light‐weight bodies, fast response time, on‐site testing, and wireless communication. This chapter discusses the various principles, materials, and designs used for measuring four of the key parameters for water quality testing: pH, dissolved oxygen, electrical conductivity, and temperature.