Probe for Measuring Gradients of the Ph Value
Original Publication Date: 1985-Apr-01
Included in the Prior Art Database: 2005-Feb-18
The pH gradients in aqueous solutions are determined by measuring the pH value at different points, using a chain of miniaturized glass electrodes. A probe with such glass electrodes is schematically illustrated. Fig. 1 shows a top view, and Figs. 2A and 2B show two cross-sections through the probe along lines A and B of Fig. 1. The probe comprises a silicon wafer 1 into which a multitude of channels 2 (of which only three are shown) are etched with a typical width of 3 mm and a length of 40 mm. The channels, arranged in parallel to each other, have a centerline-to-centerline distance of the order of 10 mm. A Pt metallization 3 extends into one end of channels 2 (Figs. 1, 2A). A very thin (5 mm) glass foil 4 covers the silicon wafer 1 and bridges channels 2. Glass foil 4 is bonded to silicon wafer 1, e.g.