A conductivity sensor adapted for use in the conductimetric analysis of liquids includes a pair of conductivity electrodes incorporated into a conductivity cell assembly having a liquid flow control chamber, sensing chamber, and liquid exit chamber. Liquids to be measured are pumped into the liquid flow control chamber, where any turbulence in the liquid is dampened. The non-turbulent liquid is passed from the liquid flow control chamber to the sensing chamber, where the conductivity of the liquid is determined. The sensing chamber is adapted for changing the height of a column of liquid between the pair of conductivity electrodes in order to vary the cell constant of the sensor. The non-turbulent liquid is passed from the sensing chamber to the liquid exit chamber, where it exits the sensor. The sensor is well-suited for use in measuring conductivities of plating bath solutions and monitoring concentrations of major constituents of plating bath solutions.

A conductometric gas analysis cell comprised of a porous Teflon membrane supporting interdigited electrodes separates a thin layer of deionized water from a gas phase to be analyzed. Volatile species in the gas phase pass through the membrane and increase the conductance of the water which results in increased current flow between the interdigited electrodes.

A system for monitoring patient respiration include a disposable, convenient moisture detection device. The device is minimally intrusive to the laminar flow of gases and has minimal liquid collection volumes. It is characterized by high sensitivity at rapid response rates.

An ink filter (15) is provided in an ink supply conduit (12). First and second electrodes (21), (22) are disposed in the conduit (12) upstream and downstream of the filter (15) respectively. A sensor means (23), (24), (27), (28), (32) measures an electrical parameter such as the electrical resistance, capacitance or the like between the electrodes (21), (22) which varies as a function of the degree of clogging of the filter (15). An indicator (34) such as a light or lights (36), analog meter (33) or the like indicates the magnitude of the electrical parameter and thereby whether the filter (15) is clogged or unclogged.

An apparatus and method for measuring conductive airborne particulates in which a filter (16) having a pair of interdigitated electrodes (18, 20) printed on its surface is placed in a sampling chamber (14). A pump (10) draws air (12) through the chamber and through the filter with airborne particles being deposited on the side of the filter with the electrodes. The resistance between the electrodes is measured (22) without removing the filter from the chamber.