Advanced Physical and Chemical Techniques for Sensor Surface Treatment

Massive progress has been made in sensor technology over the past decades; however, limitations still exist. The possibility of improving sensor features and performance has been investigated through surface modification. This type of modification is especially useful in surface-based sensors, such as nanosensors, which rely mostly on the high surface area to volume ratio of nanomaterials. Sensor surface modification can manipulate properties of the sensor surface, enhance the surface area by changing the morphological structure, or improve selectivity and sensitivity to stimuli. In some cases, it is also used to tailor sensors for specific applications, such as attaching biomolecules onto sensor surfaces for biosensing applications. Several approaches to sensor surface modifications that are classified into physical and chemical approaches will be discussed. Physical approaches target the adjustment of the physical properties of the sensor surface. Simple physical techniques, such as surface coating used for the protection and preservation of sensing materials, will be spotted. Moreover, techniques concerned with changing patterns and features of the sensor surface, including lithography and morphological modification, will be explained. Chemical surface modifications entail techniques that can alter the chemistry of the sensor surface. Techniques such as functionalization and molecular self-assembly involve the addition of specific functional groups, or entire molecules, to improve chemical affinity toward certain chemicals or gases. Chemical modifications by the manipulation of sensor surface defects, including material doping and intercalation concepts, will be addressed. The addition of impurities to certain matrices was found to improve the sensitivity and conductive properties of sensors.