Electro-based sensors and surface engineering

Electro-based sensing strategies played an important part in the early development of the sensing field, having predated methods based on position in the market today (Schuhmann and Bonsen 2003). The electrobased strategies are distinguished in that they are intrinsically interfacial, wherein biological recognition, or physical changes that follow from a recognition event, directly change the electrical properties of a contacting material. The simplicity of an interfacial assay and the sensitivity with which electrical currents and potentials can be measured are in large part responsible for the importance of these assays. This class of strategies also benefits from the localization of binding events to an interface, leading to an enhanced discrimination between specific analytes and background array formats and integration with microfluidic structures. The central importance of sensors in several industrial contexts, and the many successful products that have been developed and are now widely distributed, give this field a strong emphasis on product development and commercialization. Research and development activities in electro-based sensors maintain an even balance between basic research to develop novel transduction strategies, engineering activities to integrate established sensing mechanisms into prototype devices, and industrial activities to analytes. Additionally, these strategies are compatible with extension to fluorescence, mass spectrometry, and radioactivity; they retain a central commercialize products. This maturation of the sensing field impacts basic research in academic and government laboratories, attaching an importance to market factors that will ultimately define cost structures, performance metrics, and reliability of sensors. This chapter addresses the development and implementation of electrobased sensors in the United States, Europe and Australia, and Japan, including key underlying technologies critical to surface engineering, receptor design, and sample preparation. (These technologies are also important to sensors based on alternate transduction schemes, as indicated in other chapters of this report) This chapter begins with a description of important current activities in electro-based sensors development, with an organization that reflects the various physical transduction strategies. The second section comments on critical underlying technologies that are important to the performance and development of these sensors: these factors are also important to sensing strategies based on non-electrical schemes and will be addressed in other chapters. The final section provides bullet-point summaries of the comparison of sensing programs in the United States, Europe and Australia, and Japan.