Abstract: A contacting-type conductivity sensor is provided. A first insulating layer has a proximal surface to contact a liquid sample, and an opposite, distal surface. A plurality of electrodes is disposed on the proximal surface of the first insulating layer. Each of a plurality of conductive vias is electrically coupled to a respective one of the plurality of electrodes, where each via defines a conductive path from the proximal surface to the distal surface of the first insulating layer. A plurality of traces is disposed adjacent the distal surface of the first insulating layer, and each of the plurality of traces is electrically coupled to a respective one of the plurality of conductive vias. A plurality of conductors is provided where each conductor is electrically coupled to a respective one of the plurality of traces. A cover layer is coupled to the first insulating layer.

Abstract: A sensor for analyzing a liquid sample is provided. The sensor includes a sensor body defining a chamber therein. A sensing cell is disposed within the chamber and is adapted to contact the sample solution. The sensing cell has a sensing cell fill solution therein, and a sensing electrode disposed within the sensing cell fill solution. A reference fill solution is disposed within the sensor body. A reference junction is arranged to contact the reference fill solution and the sample solution. A temperature sensitive device is disposed within the body and is configured to provide a temperature sensitive device output. A reference electrode is disposed within the sensor body in contact with the reference fill solution. A solution ground electrode is disposed within the sensor body and spaced from the reference electrode.

Abstract: A pH sensor is provided. The pH sensor includes a body, a glass electrode, a reference electrode and a solution ground. The glass electrode is disposed on the body to contact a liquid sample. The reference electrode has a reference fill solution disposed within the body. The solution ground electrode is operably coupled to the body and has a portion of the solution ground electrode that is disposed within a harbor such that a portion of the solution ground electrode is configured to contact the liquid sample. The body has a passageway that extends from the reference fill solution to an aperture proximate the liquid sample.

Abstract: A dissolved oxygen measurement system, and a method for calibrating a dissolved oxygen analyzer are provided. The method includes directing a pressurized cleaning fluid, having a known oxygen content, upon a sensing surface of a dissolved oxygen sensor disposed in a fluid. Then, the analyzer waits until the dissolved oxygen sensor response to the pressurized cleaning fluid is relatively stable, and stores a calibration value relative to the dissolved oxygen sensor response to the pressurized cleaning fluid. A dissolved oxygen measurement system is also provided. The system includes a dissolved oxygen sensor disposed in a fluid and a first source of a first compressed cleaning fluid that has a first dissolved oxygen content. A first valve is operably coupled to the first source and configured to selectively direct the first compressed cleaning fluid against a sensing surface of the dissolved oxygen sensor.

Abstract: A method of measuring impedance of a pH electrode is provided. A test current is applied to the pH electrode for a time duration that is less than 50 percent of a time constant that is associated with electrical characteristics of the pH electrode. A voltage response of the pH electrode is measured when the test current is applied to the pH electrode. An impedance of the pH electrode is calculated as a function of the voltage response.

Abstract: A contacting-type conductivity sensor includes a plurality of electrodes disposed on a distal surface of a substrate. The substrate includes a plurality of vias through which electrical interconnection to the electrodes is accomplished. The conductivity sensor can employ two or four electrodes and may have a temperature sensitive element disposed on the distal surface. The electrodes may be patterned or otherwise deposited using semiconductor processing techniques.

Abstract: Measurement of arsenic in an aqueous solution is provided. The pH of the aqueous solution is adjusted to a pH of about 7.0 or higher. The pH adjusted aqueous solution is then analyzed using anodic stripping voltammetry to obtain an indication of a quantity of arsenic in the solution. In one aspect, the pH is adjusted using a phosphate buffer.

Abstract: A dissolved oxygen sensor having a cathode and anode immersed in an electrolyte is designed to provide a low background current in the sensor when a potential is applied to the cathode. The background current is maintained at a desired level by selecting the area and length of a channel or path of diffusion of residual oxygen in the electrolyte to the cathode. The area (A) of the diffusion channel in relation to its length (L) is selected to be at or below a selected ratio, A/L.

Abstract: An electrochemical cell includes a measuring electrode and a reference electrode. The reference electrode includes a flowing liquid junction between a reference fill fluid and a sample. The flowing liquid junction is configured to inhibit particles from blocking or obstructing it. In one aspect a particle filter is provided before the flowing liquid junction to prevent particles from the fill fluid from entering the flowing liquid junction. In another aspect a particle filter is provided after the flowing liquid junction to prevent particles in the sample from entering the flowing liquid junction. In another aspect the flowing liquid junction has a diameter that generally increases from an aperture proximate the fill fluid to an aperture proximate the sample. On example of such a configuration is a tapered flowing liquid junction.

Abstract: An integrated luminescence sensor includes a light pipe in optical communication with a luminescence sensing layer. A source of excitation illumination is coupled to the light pipe and disposed to direct excitation illumination toward the sensing layer. A luminescent light detector is also coupled to the light pipe and is disposed to detect luminescent illumination luminescing from the sensing layer, which luminescence is related to interaction between the sensing layer and a substance of interest.

Abstract: Modification of ruthenium complex luminescence dye for oxygen sensing is provided. Generally, modification includes bonding long chain hydrophobic organic groups to the ligands of the ruthenium complex in order to increase solubility of the ruthenium complex in non-polar organic solvents. A sensor manufacture using the modified ruthenium complex luminescence dye is also provided.

Abstract: A contacting-type conductivity sensor includes a plurality of electrodes disposed on a distal surface of a substrate. The substrate includes a plurality of vias through which electrical interconnection to the electrodes is accomplished. The conductivity sensor can employ two or four electrodes and may have a temperature sensitive element disposed on the distal surface. The electrodes may be patterned or otherwise deposited using semiconductor processing techniques.

Abstract: A chloramine amperometric sensor includes a sensor body with an electrolyte disposed inside the sensor body. A membrane is coupled to the sensor body and adapted to pass chloramine therethrough. A reference electrode is disposed in the electrolyte and coupled to a first conductor. A second conductor is coupled to a working electrode that is disposed proximate the membrane. The working electrode is constructed from a noble metal in non-compact form. The non-compact form can be a Gas Diffusion Electrode, which can include metal mesh, carbon paper, carbon cloth, metal/carbon powder loaded on a porous membrane or any combination thereof.

Abstract: An amperometric sensor includes a sensor body having a distal end and an interior containing an electrolytic fill solution. A porous membrane is disposed proximate the distal end to allow diffusion of molecules or ions of interest. A working electrode is disposed within the sensor body proximate the membrane. A counter electrode is disposed to conduct current between the counter electrode and the working electrode. The counter electrode is physically isolated from the electrolytic fill solution. A method of measuring a concentration of the molecules or ions of interest is also provided.

Abstract: An improved flow-through conductivity sensor is provided. The sensor includes a current return path that has a current return conductor. At least one toroid of the sensor is removed from the flow path and configured to interact with the current return conductor to provide an indication of conductivity. Additional aspects of the invention include disposing a pair of toroids about the current return conductor; disposing a toroid about the current return conductor and configuring the toroid as a transformer.

Abstract: An ion sensitive field effect transistor pH sensor is provided with an improved sensor gate configuration. Specifically, a tantalum oxide-sensing gate is disposed on top of an alumina layer. The tantalum oxide-sensing gate provides advantageous sensitivity, while the alumina barrier layer increases sensor longevity in situations where the sensor is exposed to caustic cleaning processes such as Clean In Place processes.

Abstract: An improved flow-through conductivity sensor is provided. The sensor includes a current return path that has a current return conductor. At least one toroid of the sensor is removed from the flow path and configured to interact with the current return conductor to provide an indication of conductivity. Additional aspects of the invention include disposing a pair of toroids about the current return conductor; disposing a toroid about the current return conductor and configuring the toroid as a transformer.

Abstract: The invention relates to an internal solution ground for primary use with a pH sensor, and preferably with a multi-sensing instrument monitoring a pH sensor and one or more additional secondary sensors having non-isolated circuits. In one aspect, a pH sensor assembly includes a pH electrode, a reference electrode, and an internal solution ground wire. The internal solution ground wire shares a liquid junction with the reference electrode but is protected by the reference fill solution. In one embodiment, the internal solution ground can be electrically isolated through a capacitor or, alternately, a capacitor and resistor in parallel.

Abstract: A free chlorine measurement system and sensor are provided. In accordance with one aspect of the invention, the sensor has a porous working electrode disposed in an electrolyte proximate a porous membrane. The membrane allows free chlorine therethrough where it is reduced and generates a current. The current is related to the free chlorine concentration. The internal electrolyte solution is pH stabilized with a long-term pH stabilizer that has a solubility in water at room temperature between about 1.2 moles/liter and about 0.001 moles/liter. The stabilizer can be an acid or a base depending on whether the pH is to be stabilized at a relatively low value or a relatively high value respectively.

Abstract: A dissolved oxygen sensor having a cathode and anode immersed in an electrolyte is designed to provide a low background current in the sensor when a potential is applied to the cathode. The background current is maintained at a desired level by selecting the area and length of a channel or path of diffusion of residual oxygen in the electrolyte to the cathode. The area (A) of the diffusion channel in relation to its length (L) is selected to be at or below a selected ratio, A/L.