Optical test strip for calcium determination based on a neutral ionophore

Use of digital reflection devices for measurement using hue-based optical sensors

“…As usual in this type of sensors the central zone of the sigmoid can be linearized for calibration purposes and the equation H = 1.1 (±0.1) + 0.16 (±0.03) [K(I)]; R 2 = 0.998 was obtained. The limit of detection calculated as usual [37] from this regression was 3.5 × 10 −4 M, a result that is worse than that obtained working from images acquired in transmission mode (3.6 × 10 −5 M) [1].…”

Potassium disposable optical sensor based on transflectance and cromaticity measurements

“…The K exch value to obtain an optimal fit of the experimental data was calculated according to [27]. In all cases the activities were calculated according to the two-parameter Debye-Hückel formalism [28].…”

“…The measuring range of the sensors based on bulk optode membranes, which exhibits a sigmoidal shape response function, can be obtained in two main ways: (i) assimilating the central part of the sigmoidal response curve to a straight line; this option is the most commonly employed one and has been defined in various forms [27]; and (ii) linearising the whole sigmoidal curve by means of a mathematical transformation [30]. Here we test the two options.…”

Optical sensor for the visual detection of mercury using mesoporous silica anchoring porphyrin moiety

“…Such heterogeneous systems for various applications have been reported by incorporating the functional chromophore onto sol-gel glasses, fibers, filter papers, and mesoporous materials. [16][17][18][19] In these systems, the solid support lends stability while the chromophore provides the necessary binding site for the analyte, leading to changes in its properties such as color, fluorescence and nonlinear optical behavior. 20,21 Among the inorganic host materials, mesoporous materials have attracted much attention for electronic and optical applications due to their high surface area, uniform porosity, and low absorption and emission in the visible spectrum, making them suitable host matrices for sensing molecules or ions.…”