Optical Biosensors Towards Point of Care Testing of Various Biochemicals

Book chapter, 2022

A steady rise in the use of point-of-care devices is warranted by the growing demand for medical attention and increased use of portable biosensing devices across various industries in different domains. Portable point-of-care devices provide simple, cost- and time-effective, reliable detection of various chemicals such as biomolecules, toxins or environmental pollutants, and microscopic entities such as parasites, viruses, bacteria and other pathogens. Among different biosensors, optical biosensors offer high sensitivity in the range of 10−6–10−8 RIU, real-time monitoring capability, cost-effectiveness, rapidity and compatibility to miniaturization. The versatility of this class of biosensors makes them attractive candidates, holding promising potential for use as next-generation point-of-care testing devices. Optical biosensors use optical field parameters such as the amplitude, frequency, phase and polarization state to probe molecular interactions. Optical biosensors can be classified into label-based (e.g. fluorescence) and label-free (e.g. surface plasmon resonance) biosensors. Advances in the optical biosensing domain towards integrated optics, integration of microfluidic technology and microelectromechanical systems-assisted sensor fabrication techniques have significantly contributed to the field as they facilitate the fabrication and development of portable, cost-effective and high-throughput optical biosensing device. Label-based techniques offer excellent sensitivity and specificity for interrogating biomolecular interactions. Whereas label-free techniques directly detect and interpret the changes in optical parameters of the incident light wave on the biomolecules embedded on sensor surfaces, without hindered by photo-bleaching or other limitations faced by marker-dependent approaches. This chapter provides a brief overview of currently available label-based and label-free biosensors and discusses the potential and key limitations that require further advances in the field to facilitate successful commercialization of these techniques.