Abstract: A conductivity sensor is disclosed that comprises a forked electrode support that includes a first opposing arm and a second opposing arm spaced apart by a slot. Both the first arm and the second arm include a plurality of electrodes embedded in each arm. The first and second arms and the slot are capable of retaining a volume of fluid within the volume defined by the arms and the slot such that the conductivity of the fluid in the slot can be determined. The conductivity sensor is wipeable by a reciprocating wiper assembly positioned adjacent the forked electrode support such that the wiper element can travel through the slot and remove contaminants from the slot and the plurality of electrodes in each of the first and second arms. Also disclosed are methods of making the conductivity sensor.

Abstract: Disclosed is a microfluidic device comprising at least one micro-aliquotter for dispensing fixed or variable volumes. The micro-aliquotter includes an rigid, dimensionally stable foundational layer having a fluid port therein that is in fluid communication with a channel within the microfluidic device, and an elastic film positioned on the foundational layer where the film covers the fluid port. The elastic film is sealed to the foundational layer so fluids entering through the fluid port can be captured between the elastic film and the foundational layer. The elastic film being expandable from a rest position on the foundational layer to a dispensing, or aliquotting, position in which an aliquot volume of a fluid is contained between the film and the foundational layer.

Abstract: A method for digitally controlling the resistive output of a temperature probe is disclosed. The system is comprised of a temperature sensor, a processor and a means under the control of the processor for modifying the resistive output such as a digital potentiometer. In one embodiment, the processor reads the temperature sensor and adjusts the potentiometer based on a correlative or predictive technique so as to provide a modified output that matches that of a standard resistive temperature probe and is compatible for display on a multi-parameter monitor.

Abstract: A method for measuring channel flow discharge comprising the steps of: locating a platform carrying a fluid flow measurement device at a plurality of stations at spaced locations across a channel; determining the velocity of the platform at each station by averaging the differences between the position of the platform at a first time (t) and the position of the platform at a second time equal to the first time plus a position averaging interval (PI) for a plurality of different first times; obtaining current flow vs. depth profiles at each station by adjusting current velocity as measured by the current flow measuring device for the platform velocity; determining the flow discharge at each station.

Abstract: A microfluidic module that comprises an adhesiveless self-bonding rebondable polyimide film.

Abstract: A method for digitally controlling the resistive output of a temperature probe is disclosed. The system is comprised of a temperature sensor, a processor and a means under the control of the processor for modifying the resistive output such as a digital potentiometer. In one embodiment, the processor reads the temperature sensor and adjusts the potentiometer based on a correlative or predictive technique so as to provide a modified output that matches that of a standard resistive temperature probe and is compatible for display on a multiparameter monitor.

Abstract: A method for digitally controlling the resistive output of a temperature probe is disclosed. The system is comprised of a temperature sensor, a processor and a means under the control of the processor for modifying the resistive output such as a digital potentiometer. In one embodiment, the processor reads the temperature sensor and adjusts the potentiometer based on a correlative or predictive technique so as to provide a modified output that matches that of a standard resistive temperature probe and is compatible for display on a multi-parameter monitor.

Abstract: A sonde comprising a first sensor and a second sensor adjacent the first sensor, the first sensor including an optical window and a wiper element, the wiper element rotating on a shaft extending from the first sensor so as to clean debris from the window, a brush extending from the wiper element beyond the perimeter of the first sensor such that the brush contacts the adjacent second sensor and removes debris which accumulates on the second sensor.

Abstract: A method is provided for constructing a platform for use in a sensor in a microfluidic device. The method may include the steps of selecting a polymeric film, laser drilling at least one frustoconical pore in the film, depositing a layer of metal suitable for use as an electrode over a wall of the pore, and depositing a membrane capable of detecting an analyte in the pore over the metal layer. The method may also include the additional step of forming a diffusion limiting layer in the pore at an exit end of the pore before depositing the membrane capable of detecting an analyte.

Abstract: A bilateral biosensor based upon a microporous architecture is provided which seeks to reduce the effect of co-reactant concentration limitations by utilizing a new sensor microgeometry. If implemented on the appropriate scale, the new sensor design augments substantially the concentration of oxygen, or other co-reactants or reagents, in the reaction zone of the sensor. Performance enhancements over traditional microscale devices employing unilateral orientation are accomplished, in one embodiment, by allowing analyte to enter the sensor from one side of the sensor, while allowing a co-substrate to enter from both sides of the sensor.

Abstract: In one embodiment, a fluidic module, such as a microfluidic module, has a fluid-flow channel, an electroosmotic flow membrane positioned in the channel, and a cathode located on one side and an anode located on the other side of the membrane so that an electrolyte in the channel is transported through the membrane in the presence of a voltage. In another embodiment, the channel has a port, a flexible and fluid-impermeable diaphragm is added, the electrolyte is contained in a reservoir, and the membrane moves the bladder which acts as a valve for fluid leaving the channel through the port. In a further embodiment, electrolyte in a first reservoir is transported through the membrane to move the bladder to force fluid out of a second reservoir.

Abstract: A sampling probe for withdrawing and filtering a portion of material from a vessel having an inner chamber containing the material and a port for receiving a probe. The sampling probe comprises a casing having a sample inlet, a pumping chamber having a pump for drawing a portion of the material into the pumping chamber through the sample inlet, and a filter chamber downstream of the pumping chamber. The filter chamber includes a filter which divides the filter chamber into a retentate portion and a filtrate portion, wherein at least part of the withdrawn material passes through the filter into the filtrate portion.

Abstract: A method of fabricating a module having fluid flow channels in communication with a diaphragm valve using self-bondable polyimide sheets wherein the sheets are directly interfacially bonded to one another except in the region corresponding to the diaphragm valve without using an adhesive is disclosed.

Abstract: An improved apparatus for measuring conductivity or resistivity compensates for series capacitance and parallel capacitance. A sine wave excitation potential is applied to the series combination of a reference resistance and a conductivity cell. The voltages across the reference resistance and the cell are sampled. To compensate for series capacitance, both sampled voltages are synchronously rectified with respect to the phase of the sampled reference resistance voltage. To compensate for parallel capacitance, both sampled voltages are synchronously rectified with respect to the phase of the sampled cell voltage. The rectified voltages are integrated and the cell conductivity or resistivity is calculated from the product of the reference resistance and the ratio of the integrated voltages.

Abstract: Microfluidic analyzers are used to sense a plurality of analytes in whole blood, diluted blood, plasma or serum. Additionally in the rapidly growing fields of cell culture growth and fermentation, it is often necessary to measure glucose, glutamine, lactate, NH3, phosphate and iron in micro-scale fluid flow analysis systems. The present application is directed to a fluid flow module that allows for analyte sample flow therethrough while providing a site for the location of a sensing element or elements therein to detect analyte presence and/or concentration. The module is designed for microfluidic flow rates and volumes and can be discarded after use with simple replacement by another module.

Abstract: An improved laminated enzyme containing membrane for polarographic sensors and methods of making these membranes are disclosed. The laminated membrane comprises an outer, support layer having pores therein of greater than about 300 angstrom units in diameter and this outer membrane has a pore density of less than 6.times.10.sup.8 pores/cm.sup.2. The porosity of the outer membrane may be on the order of 0.001-0.2%. An enzyme layer is interposed between the support layer and an inner, barrier layer; the latter positioned near the working electrode of the polarographic cell. The enzyme layer comprises a buffer solution dispersed therein wherein the molarity of the buffer solution is between about 1.times.10.sup.-6 to 0.1 M. The enzyme layer is highly dense as measured by a molar response ratio of ferrocyanide:H.sub.2 O.sub.2 of less than about 0.05.

Abstract: A microfluidic analyzer module. The module is constructed of a plurality of channel forming laminate layers that are directly bonded together without adhesive or other possible contaminant source located proximate the flow channels. The channel forming laminate layers define a network of fluid flow channels. A valve containing layer is directly, adhesivelessly bonded over the channel containing layers. A flexible valve member integral with the valve layer opens and closes communication between feed and sensor channels of the channel network.

Abstract: Methods for forming thin layer barrier layer films for use in enzyme containing laminated membranes and membranes formed thereby are disclosed. The barrier layers exhibit improved acetaminophen rejection and comprise a cellulose acetate/cellulose acetate butyrate blend. The thin layer barrier membranes are formed from a plural solvent containing solution and are cured at a critical temperature of about 102.degree.-114.degree. F., most preferably at about 106.degree. F.-114.degree. F. while traveling through a circulating hot air oven. Alternatively, the membranes can be cured at room temperature or in a stagnant oven at temperatures of from room temperature to about 175.degree. C. (350.degree. F.) for a period of from about 10 minutes to 1 hour.

Abstract: A Clark-type gas detection apparatus includes a sensor electrode and a reference electrode exposed to an aqueous electrolyte solution which is isolated from a liquid medium surrounding the apparatus by a semi-permeable membrane. A preferred reference electrode for use in Clark-type apparatus comprises silver/silver chloride. Through the addition of an effective amount of a sulphate-based co-electrolyte to an electrolyte solution having a relatively low chloride ion content, it is possible to obtain an electrolyte solution having an ionic conductivity comparable to that of chloride-based electrolyte solutions currently used in Clark-type sensors while retaining sufficient chloride ion to drive the oxidation reaction near the reference electrode. The relatively low chloride ion content of the electrolyte solution of the present invention tends to suppress the dissolution of silver chloride from the reference electrode, and, consequently, the deposition of silver on the indicating electrode.