GB1418337A - Measurement of fluid on pieces of wettable material - Google Patents

Abstract

1418337 Electrical measurements; determination of amount of fluid in gingival cavity &c. HARCO ELECTRONICS Ltd 27 April 1973 [28 April 1972] 20086/73 Headings G1B and G1N In a device for the quantitative measurement of fluid on pieces of wettable material, e.g. paper strips, a casing 33 houses circuitry, Fig. 6 (not shown), supplied by a regulated power supply, Fig. 7 (not shown), and a digital read-out meter 16, the circuitry including a variable capacitor having a pair of plates and a dielectric piece of material engageable therebetween, means being provided for connecting the capacitor to the meter 16 whereby the quantity of fluid on the material may be ascertained from the read-out in micro-amperes, As shown in Fig. 9, a paper strip has a crease 38 formed there across and a ridge 39 impressed thereon for stiffening purposes. As described, the capacitor is arranged in an oscillator circuit to vary the base bias of a transistor which is read-out on meter 16. In use, the strip is engaged between two anodized aluminium jaws 20, 21 forming the capacitor plates, jaw 21 being fixed but adjustable, and jaw 20 being movable and spring-biased to apply constant pressure to the strip. The device may be used to determine the quantity of gingival fluid by insetting the strip in the gingival crevise between a tooth and the gum, the calibrate micro-pipettes, micro-burettes, loops or syringes, to determine the quantity of sweat, lacrinal fluid (for determining wearer acceptance of contact lenses), and saliva (for determining suitability for wearing dentures). The strip with its wetted area may be laid under a transparent grid and viewed through a magnifying glass or microscope, the wetted area being determined by counting grid squares.