Test strips belong mostly to the class of optical sensors. Because of their relative importance we will devote a separate chapter to this class of sensors. Test strips have been developed for the visual detection of the presence of an analyte that results in a color change at the surface of the strip. With the advent of microelectronics small portable spectrometry systems have been developed that can quantify a change in color and indicate the response of the system on a digital display.
For these reasons, in addition to colorimetric test strips there are also test strips based on other principles, e.g., amperometric methods which are available. Test strips are available for a wide variety of analytes, including inorganic and low molecular organic compounds as well as biological substances up to microorganisms. Actually, test strips find a lot of application in medical diagnosis.
In the following sections of this chapter the recent developments in the analysis of target molecules with regard to test strips are reproduced.
N-alkylaminopyrazole ligands have been used for test strips for the rapid and highly sensitive detection of mercury in water. Hg2+ can be detected at concentrations lower than 0.1 ppb (1).
A test strip for the detection Hg2+ is based on deoxyribonucleic acid functionalized gold nanoparticles. The interaction of mercury ions with thymine and streptavidin-biotin effects a visual change in color. The detection limit ...