Abstract: An acoustic Doppler system comprising a plurality of acoustic transceivers, an acoustic subsystem controller and a main processing unit operatively connected to the acoustic subsystem controller. A first of the plurality of acoustic transceivers operates at a first acoustic frequency and is operatively connected to a first group of transducers producing an acoustic signal. A second of the plurality of acoustic transceivers operates at a second acoustic frequency and is operatively connected to a second group of transducers producing an acoustic signal. The first and second acoustic transceivers are adapted to operate concurrently at the first and second acoustic frequencies. The acoustic subsystem controller is operatively connected to the first and second acoustic transceivers and controls the acoustic signals produced by the first and second group of transducers.

Abstract: A probe head is disclosed that is detachable from a probe body containing electronics. The probe head including a housing enclosing a sensor and at least part of an electrical connector electrically coupled to the sensor. The housing has a coupling member positioned to detachably connect the housing to the probe body, and when the probe head and probe body are coupled, the electrical connector electrically couples the sensor to the electronics in the probe body.

Abstract: A process of assembling a probe that includes providing a circuit board that is connectable to a sensor and is connected to a first electrical connector and sliding a housing that has a first end and a second end over the circuit board. The process includes sealingly connecting the first end of the housing and the first electrical connector with a water-tight seal and sealing the second end of the housing with a water-tight seal. Also disclosed is a probe made by the disclosed processes and a sonde including a probe made by the disclosed processes.

Abstract: Turbidity heads for a turbidity sensor or probe and the resulting sensor are disclosed that include a light source providing an outgoing light ray, a photodetector capable of detecting an incoming light ray; an isolator separating the light source from the detector portion; and a first reflector in the path of either the outgoing light ray or the incoming light ray. The first reflector is positioned to reflect either the outgoing light ray or the incoming light ray to achieve a measurement angle defined between the outgoing light ray and the incoming light ray of ninety degrees plus-or-minus two and a half degrees to comply with the standard ISO 7027 for turbidity measurement.

Abstract: An acoustic Doppler system including an acoustic subsystem controller operatively connected to a plurality of acoustic transceivers, with a first of the plurality of acoustic transceivers, operating at a first acoustic frequency, operatively connected to a first group of at least one transducer, and a second of the plurality of acoustic transceivers, operating at a second acoustic frequency, operatively connected to a second group of at least one transducer, where the acoustic subsystem controller includes a digital circuit configured to sample analog signals received from the first and second groups of transducer in pairs having a pair-wise sampling frequency that is four times the operating frequency of associated acoustic transceiver.

Abstract: An underwater sensor device comprises a submersible housing including one or more housing components, one or more sensors for monitoring and collecting water characteristics, a controller for controlling operations of the one or more sensors and an graphical user interface mounted to the housing that displays the water environmental data. The housing defines a channel that extends through one of the housing components, and at least one of the sensors is mounted to the housing and extends into the channel. The controller is disposed within the housing and is operatively connected to the one or more sensors.

Abstract: A method of making a microfluidic module is disclosed that includes forming a fluid flow channel in a self-bonding rebondable polyimide film to provide a channel sheet, the self-bonding rebondable polyimide film having a first mask layer self-bonded thereto; removing the first mask layer from the channel sheet after forming the fluid flow channel; and self-bonding the surface of the channel sheet exposed by removal of the first mask layer to a cover sheet.

Abstract: A system and method for measuring the flow of water in cross-section of a body of water is presented. The system and method comprises a housing having a first transducer and a plurality of second transducers, wherein the first transducer produces an acoustic signal for determining the depth of the body of water, and the second transducers each produce an acoustic signal for determining the velocity of a volume of water by measuring the Doppler frequency shift in the returned echo.

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 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: 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 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.