Optoelectronics and Optical Bio-Sensors

*Thamer Tabbakh, Noha Alotaibi, Zahrah A. Almusaylim, Sundos Alabdulkarim, N.Z. Jhanjhi and Nawaf Bin Darwish*

#### **Abstract**

Optical biosensors (OB) have wide applications in bio-fields; they are valuable monitoring and detecting tools in therapy, food, defense and military industries. They also applied in environmental monitoring quality (i.e. water, soil and air). In recent years, biosensors have been applied in the early detection of number of diseases such as; alzahimer's disease and infecting viruses. The OB detection technology is based either on label- based or label-free method. They are composed of integral physical and biological systems, which can provide sensitive analysis for bio-analytes. This chapter will shade the light over the OB principles and their applications with the focus on the surface plasmon resonance.

**Keywords:** biosensors, optical , fabrication , bio-analyte, detection, monitoring

#### **1. Introduction**

OB are classified as one of the most reliable recognizing and detecting devices. Ideally, they are composed of integrated system of photonic sources and biomolecule recognition component, which in spatial contact with the transductor, that can recognize and interact with specific molecule analytes present in sample [1, 2]. The interaction induces a variation in an electrical, optical or mechanical property of the transduces, the degree of variation reflects to the quantity of the analytes [2]. The fundamental structure of OB features the 1- bio-recognition element, such as; enzymes, nucleic acids, antibodies, microbes, polysaccharides. 2- Single transductor including electrical current, potential, impedance, EM radiations, mass, optical, piezoelectric or thermal, and 3- amplifier [3–6]. The interaction occur between bio-recognition element and analyte produces a signal due to a number of factors, either alteration in proton concentration, release or capture of gases or electron, or light mission, absorption or reflectance, heat emission, change in mass [4]. The produced signal can be converted into measurable value (e.g. current, temperature alteration) by the transducer as shown in **Figure 1**.

OB provide an accurate and sensitive, timely detection technology [8]. In the current era, having such an analytical and informative features become an essence, especially in healthcare diagnostics, environment quality monitoring, food safety and security, biological warfare and biodefense [9]. Therefore, it become an attractive tool that subjected to a modification and development and emerging with nanotechnologies, microelectromechanical systems (MEMS), biotechnologies [10–12]. This reflected in the rapid advancement in biosensors, which is associated with the market growth application and is estimated by 21.18 billion USD in

**Figure 1.** *Schematic diagram illustrate biosensor structure [7].*

North America in the 2020 [13]. There is no universal or standard OB for detection; however, there are groups of OBs developed for specific applications and targets.
