Abstract: A slurry analysis system (14) for estimating a first characteristic of a slurry (12) having a plurality of particles (18) suspended in a dispersion medium (20) can include a flow restriction assembly (40); a sensor assembly (43) that senses a sensed condition of the slurry (12) as it flows through the flow restriction assembly (40); and a control and analysis system (26) that estimates the first characteristic of the slurry (12) based on the sensed condition. Further, the control and analysis system (26) can select a selected clogging behavior using the sensed condition, and estimate the first characteristic based on the selected clogging behavior.

Abstract: Methods and systems are provided for measuring the zeta potential of macroscopic solid surfaces including and not limited to: porous samples, flat substrates, coarse particles, and granular samples. Methods include: subjecting the sample to an injection of a first aqueous solution at an initial pressure with an initial ion concentration; measuring a first electrical conductivity and a first temperature of the first aqueous solution; measuring a first pH and a second pH of the first aqueous solution immediately before and after passing the first aqueous solution through the sample; measuring a first ion concentration and a second ion concentration of the first aqueous solution immediately before and after passing the first aqueous solution through the sample; and processing the measured data to derive a first zeta potential from the first electrical conductivity and the first temperature.

Abstract: A system and method for characterizing a totality of particles selects a class of the totality of particles having a defined mobility; determines the total particle concentration of the class of particles; filters the class of particles using the filter apparatus and determines a filtered particle concentration indicative of the particles of the class which penetrate the filter apparatus; and determines at least one morphological parameter based on the fraction of particles of a class penetrating the filter apparatus.

Abstract: A microparticle detecting apparatus is disclosed and includes at least one detection unit, each of which includes: a first sieve having at least a first mesh, a separator stacked on one side of the first sieve and having a separator hole, and a second sieve stacked on one side of the separator and having several second meshes. The diameter of the second mesh is smaller than that of the first mesh, and the first and second meshes are misaligned with each other in a vertical direction of the first and second sieves. The detection unit further includes at least a sensor aligned with the first or second mesh for detecting microparticles trapping into the first mesh or passing through the second mesh. Therefore, the microparticle detecting apparatus is suitably used for detecting or counting any microparticles with different size, to effectively shorten the detection processes of sample fluids.

Abstract: Various systems, methods, and devices are provided for focusing particles suspended within a moving fluid into one or more localized stream lines. The system can include a substrate and at least one channel provided on the substrate having an inlet and an outlet. The system can further include a fluid moving along the channel in a laminar flow having suspended particles and a pumping element driving the laminar flow of the fluid. The fluid, the channel, and the pumping element can be configured to cause inertial forces to act on the particles and to focus the particles into one or more stream lines.

Abstract: The present invention relates to a fluid measuring device comprising a capillary device and a non-linear response device. The capillary device typically having a flow channel comprising a contraction with a sidelet upstream and sidelet downstream of the contraction, the sidelets each comprises a pressure sensor arranged to determine the pressure drop over the contraction, the geometry of the flow channel of the capillary device being adapted to provide a flow response by the linear effects in the fluid, with the least response from the non-linear effects in the fluid. The non-linear response device typically having a flow channel connected to the flow channel of the capillary device, the flow channel of the non-linear response device comprising sidelets arranged to determine a pressure drop over at least a part of the flow channel, wherein the geometry of the flow channel of the non-linear response device being adapted to provide a flow response primarily driven by the non-linear effects in the fluid.

Abstract: Contaminant mass collection in saturated sedimentary environments for bioavailability determination. A casing includes a screen between the environment that is subject to sampling, such as a saturated sediment and the device itself. The casing includes a water intake zone, a pump, and sorptive media. The water intake zone, the pump, the screen and the sorptive media, are all operably linked in sequence. The screened casing is secured to form an in situ device; the screen is in fluid communication with the water intake zone and excludes endemic sediments and aquatic life. The in situ device is deployed in the saturated sedimentary environment. The pump operates to concentrate analytes from the selected environment in the sorptive media, where the concentrated analytes include the analyte mass of time-weighted fluid samples.

Abstract: Methods and apparatus for improving measurements of particle or cell characteristics, such as mass, in Suspended Microchannel Resonators (SMR's). Apparatus include in particular designs for trapping particles in SMR's for extended measurement periods and for changing the fluid properties within the SMR during the extended periods. Methods include techniques to provide for cell growth over time and over time in response to changing fluid properties to aid in determining parameters such as drug resistance and drug susceptibility.

Abstract: A method for characterizing particles suspended in a liquid, in a self-contained disposable cartridge for single-use analysis, such as for single-use analysis of a small quantity of whole blood. The method characterizes particles in liquid and samples a small and accurate volume of liquid. The cartridge includes a housing having a mixing chamber and a collection chamber separated by a wall containing an opening, a first bore in the outer surface of the housing for entrance of a liquid sample, a first cavity for receiving and holding a first liquid sample, and a second cavity for receiving and holding a second liquid sample.

Abstract: Methods and systems are provided for detecting presence of a target particulate of predetermined size (e.g., engine wear debris) in a fluid (e.g., an engine lubricant) by providing at least one pair of serially fluid-connected upstream test and downstream reference filtration elements in the fluid. At least the upstream test filtration element has a filtration size rating that is sufficient to remove a predetermined amount of the target particulate from the fluid. The differential pressure of the fluid may then be measured (e.g., by suitable pressure transducers) across each of the test and reference filtration elements. By comparing the differential pressure across the test filtration element to the differential pressure across reference filtration element, the presence of the target particulate in the fluid can thereby be detected by an increase in differential pressure across the test filtration element in comparison to the differential pressure across the reference filtration element.

Abstract: Methods, storage mediums, and systems for correlating pulses generated from multiple interrogation regions in a flow cytometer to particular particles flowing through the flow cytometer are provided. Embodiments of the methods, storage mediums, and systems include configurations for calibrating a flow cytometer using a calibration particle having a unique signature to determine a time-of-flight for particles flowing through the flow cytometer. Based on the calculated time-of-flight and relative positions of interrogation regions corresponding to collectors of the flow cytometer, the methods, storage mediums, and systems may further include configurations for associating other signal pulses to particles of one or more different particle sets.

Abstract: Methods and apparatus for improving measurements of particle or cell characteristics, such as mass, in Susppended Microchannel Resonators (SMR's). Apparatus include in particular designs for trapping particles in SMR's for extended measurement periods. Methods include techniques to provide differential measurements by varying the fluid density for repeated measurements on the same particle or cell.

Abstract: A new installment classifies particles by their aerodynamic size This installment produces a truly monodisperse aerosol, and can produce very narrow distributions over a wide range of sizes Particles suspended in a fluid are classified by supplying particles into suspension in a carrier flow of a fluid and providing an acceleration to the flow at an angle to the velocity of the flow to cause the particles to follow trajectories determined by the acceleration and drag on the particles caused by the fluid The particles are then classified according to their trajectories The installment has a flow channel and a source of particles to supply particles into suspension in a carrier fluid in the flow channel A drive is connected to the flow channel at an angle to the flow of fluid through the carrier flow channel, and a classification system classifies the suspended particles according to their trajectories

Abstract: An apparatus which enables characterization of particles suspended in a liquid includes a housing with a mixing chamber and a collection chamber separated by a wall containing an aperture for passage of particles between, the mixing chamber and the collection chamber, the mixing chamber further containing a mixing member, a first electrode in the mixing chamber and a second electrode in the collection chamber for conduction of an electrical current through the aperture, a processor that is adapted for controlling the measurement sequence of the apparatus and detecting possible blockage of the aperture by detecting extended duration of the electrical pulse caused by the blocking particle, and upon detection of a blockage, reversing the liquid flow while mixing in the mixing chamber for removal of the blocking particle, and restarting particle counting.

Abstract: In a system and process for ultrasonically treating a liquid having a thermal conductivity, an elongate treatment chamber housing has an inlet and an outlet such that liquid flows longitudinally through an interior space of the chamber from the inlet to the outlet. At least part of the interior space of the chamber housing is filled with a bed of particles having a thermal conductivity substantially greater than that of the liquid whereby a ratio of the thermal conductivity of the particles to the thermal conductivity of the liquid is in the range of about 2:1 to about 400:1. An elongate ultrasonic waveguide assembly extends longitudinally within the interior space of the housing and is operable at a predetermined ultrasonic frequency to generate mechanical ultrasonic vibration within the housing in direct contact with the liquid flowing therein as the liquid flows through the bed of particles.

Abstract: A fluid sensing system and method for sensing properties of a flowing fluid. The system and method entail a microfluidic device having a micromachined tube supported above a substrate, a tube passage within a freestanding portion of the tube, an inlet and outlet in fluidic communication with the tube passage and an exterior of the microfluidic device, elements for vibrating the freestanding portion of the tube, and elements for sensing movement of the freestanding portion of the tube so as to measure the vibration frequency and/or deflection of the freestanding portion and produce therefrom at least one output corresponding to a property of a fluid flowing through the tube passage. The system and method further entail placing the microfluidic device in a flowing fluid so that a fraction of the fluid enters the tube passage, and processing the output of the device to compute a property of the fluid.

Abstract: A detection unit 4 with detection means 3 and fluid inflow/outflow guide means 2 is connected to a passage 1 for fluid with conductive material or to a pool section 5 for pooling of the fluid. The detection unit 4 guides inflow and outflow of the fluid through the fluid inflow/outflow guide means 2 and detects a concentration of conductive material through the detection means 4. A concentration of conductive material in the fluid is continuously measured with high accuracy.

Abstract: A method of assessing the effect of a conduit section (11) on flow characteristics of a first fluid in a first conduit system (1). A first fluid is caused to flow through the first conduit system (1). A transverse flow parameter of the first fluid in the first conduit system (1) downstream of the conduit section (11) is detected. At least one transverse flow characteristic of the first fluid is determined from the detected transverse flow parameter. The effect of the conduit section (11) is then assessed from the determined flow characteristics.

Abstract: A nanoparticle size classifier comprising a variable flow rate system with a single diffusion element 3 placed inside a cell 2 containing inlet 1 and outlets 6 and 7, an aerosol filter 8, flow meter 9, pump 10 and pump controller 11, which enables a plurality of measurements to be obtained by means of passing an aerosol through the diffusion element 3 at various flow rates. Preferably, outlet of the diffusion cell is connected to a particle counter 5 via a three-way valve 6. The diffusion element has a net or screen that permit air through but capture some particles.

Abstract: A method for analysis of a multi-component fluid is provided based on the features of the dynamics of the self-organization processes in drying drops. An electro-acoustic resonator is utilized, with a drop of multi-component fluid placed on one end of the resonator. A shear oscillation is imparting to the resonator along its longitudinal axis. And oscillating electric voltage is placed across the resonator generally perpendicular to the direction of mechanical oscillation. Changes in the electrical conductance corresponding to changes in the acoustical-mechanical impedance can thereby be measured as the drop of multi-component liquid dries. The particular geometry of an amplitude curve includes identifying the spatio-temporal development and phase transitions is used for integral estimation of food authenticity and quality.

Abstract: A method for measuring changes in the composition of fluids, for medical diagnostics or quality control of fluids, comprising: One) placing a drop of fluid upon a quartz crystal; Two) generating ultrasonic vibrations of a predetermined frequency in the crystal; with the vibrating wave directed into the drop of fluid in a vertical direction relative to the area of the crystal upon which the drop is placed; Three) measuring voltage changes over a bridge circuit connected to the crystal, over a time period during which total or partial evaporation of the liquid occurs; Four) comparing the measurement result to previously obtained results or to predetermined data; Five) detecting changes in the composition of the fluid, from the results. detecting changes in the composition of the fluid, from said results.

Abstract: The present invention is a filter apparatus with methods to capture a desired amount of material suspended in a liquid or gas for monolayer deposition, analysis or other uses. Novel filter devices are employed to capture material which may be used for the purification or enrichment of various sample constituents or captured material may be observed or analyzed. Alternatively, particulate material may be used as a transport mechanism for proteins or chemicals which in turn may be assessed or used. The filter device employs sensors to sense pressure and adjust, halt or otherwise control sample flow. The pressure sensor essentially monitors the flow rate of sample suspension through a filter, typically responding at a predetermined pressure associated with capture of a desired amount of material on the filter. A separate valve or valve integrated with pressure sensing provides a means to adjust sample flow.

Abstract: The present invention relates to an apparatus for monitoring the progress of membrane fouling that occurs on pores as well as on the surface of a membrane by means of variations of zeta potential (?) of a hollow-fiber membrane according to time passage of filtration of a suspension, wherein colloid particles, biopolymers and other inorganic particles are dispersed, and the method thereof. Moreover, the present invention also relates to a method to identify the effect of concentration polarization layer and cake layer which can vary according to the axial position of a hollow-fiber and the developing progress of a membrane fouling by measuring the position-dependent zeta potential of the hollow-fiber membrane.

Abstract: A method and control system is disclosed that monitors the high frequency or commonly referred to as the “noise” component of a measurement signal to detect plugging conditions in fluid flow systems monitored by DP-cell based sensors. This high frequency component has contributions from the process factors like disturbances, user actions and random effects like turbulence. A test statistic ?(t) has been developed that monitors the proportion of variance introduced by process factors and random effects. By monitoring this proportion, it is possible to detect a frozen sensor that is characterized by a dramatic reduction in the variance due to process factors over a sufficiently long detection window. The method works with measurements sampled at frequencies commonly achievable in a process environment.

Abstract: A filter device is used to capture a desired amount of material suspended in a liquid or gas. The device includes a planar filter 530 mounted in a chamber defined by a body member having an upper body 510, a lower body 520, an inlet port 525, and an outlet port 515. The filter includes porous portions 540 and 545. Porous portion 545 is centrally arranged and is more restrictive to flow than portion 540. The filter is designed such that upon portion 540 capturing a desired amount of material, a predetermined pressure change exists across the filter. The predetermined pressure change causes the filter to deform and conform against an inner surface of the upper body resulting in all suspension flowing through the apparatus to flow through the more restrictive second portion 545.

Abstract: The present invention relates to physical chemistry and can be used for a quality test of liquids, in particular, multi-component liquid products, to ascertain the conformity of various process liquids, pharmaceutical preparations, foodstuffs, biological liquids to standard in pharmacology, food processing and chemical industries, and in medical diagnostics. The method of invention enables determining of the mechanical impedance within a drop (1) of test liquid having a specified volume, in the preferred embodiment, 5 mcl, placed on the surface of a piezoelectric resonator (3) of ultrasound frequencies, which provides for excitation of shear modes within drop (1) while it is drying up. The obtained time dependence of the mechanical impedance of drop (1) is used as the information parameter.

Abstract: Apparatus and methods for sensing one or more physical parameters at a remote location while minimizing or eliminating contact between reservoir fluids and the like at the remote location and the sensor used to sense the physical parameters. In one example arrangement, the apparatus includes a tubing containing a communication cable and a sensor in communication with the cable, the sensor being located within the tubing proximate the remote location. The apparatus is configured to impose a barrier of a fluid between the sensor and the environment at the remote location. A fluid barrier reservoir containing the barrier fluid is also provided in some example arrangements.

Abstract: The present invention relates to an apparatus for monitoring the progress of membrane fouling that occurs on pores as well as on the surface of a membrane by means of variations of zeta potential (&zgr;) of a hollow-fiber membrane according to time passage of filtration of a suspension, wherein colloid particles, biopolymers and other inorganic particles are dispersed, and the method thereof. Moreover, the present invention also relates to a method to identify the effect of concentration polarization layer and cake layer which can vary according to the axial position of a hollow-fiber and the developing progress of a membrane fouling by measuring the position-dependent zeta potential of the hollow-fiber membrane.

Abstract: Apparatus (20) for testing the extent of contaminants in a fluid during a test period, comprises: a source (Ps) of pressurized fluid to be tested; a fluid sump (R); a first flow restriction (R1) adapted to be supplied with fluid flow from the source, the first flow restriction being configured as an annular clearance between a first land (24) and a first bore (22) and being sized and arranged so as to be progressively occluded by contaminants in the fluid flow during said test period; a second flow restriction (R2) arranged between the first flow restriction and said sump, the second flow restriction being configured as an annular clearance between a second land (25) and a second bore (22), the second flow restriction being substantially the same dimensionally as the first flow restriction so that the second flow restriction will not be occluded by contaminants passing through the first flow restriction and the pressure drops across each of the flow restrictions will be substantially equal at the beginning of

Abstract: The invention provides an improvement in apparatus (20) for testing the level of contaminants in a fluid during a test period. The apparatus has a source of pressurized fluid (Ps) to be tested; a fluid sump (R); and a test passage (48) which is substantially free of occluding contaminants at the beginning of the test period and which is adapted to be supplied with a flow of fluid from the source. The passage is so configured and arranged as to be progressively occluded by contaminants in the fluid flow. The apparatus also includes a device (23) defining a variable-volume chamber (47). The volume of said chamber is variable between a minimum value and a maximum value.

Abstract: Apparatus (20) for testing the extent of contaminants in a fluid during a test period, comprises: a source (Ps) of pressurized fluid to be tested; a fluid sump (R); a first flow restriction (R1) adapted to be supplied with fluid flow from the source, the first flow restriction being configured as an annular clearance between a first land (24) and a first bore (22) and being sized and arranged so as to be progressively occluded by contaminants in the fluid flow during said test period; a second flow restriction (R2) arranged between the first flow restriction and said sump, the second flow restriction being configured as an annular clearance between a second land (55) and a second bore (22), the second flow restriction being substantially the same dimensionally as the first flow restriction so that the second flow restriction will not be occluded by contaminants passing through the first flow restriction and the pressure drops across each of the flow restrictions will be substantially equal at the beginning of

Abstract: A device for determining the level of particulate contamination in a fluid power or lubrication system. Between the inlet and the outlet of the device, working fluid passes through a narrow orifice (26) defined between a cylindrical spool (22) and surrounding sleeve (20). As the orifice becomes obstructed by particulate contamination, fluid flow through the device reduces. The contamination level is assessed by measuring the characteristic reduction in fluid flow rate over a period of time. Following the measurement cycle, fluid flow through the device is reversed causing the spool to move relatively within the sleeve to an area of increased bore (40) whereby the enlarged gap allows the release of all trapped contaminants. Following this flushing cycle, the fluid is reverted to the original flow direction, the spool returns to the position within the spool that defines the narrow orifice and another measurement cycle begins.

Abstract: A membrane filtration method and an apparatus for continuously monitoring the state of a membrane during the filtration, particularly for membrane fouling due to cake or gel layers of solutes developed on the surfaces of a filtered membrane, by estimating a membrane potential and a membrane solute rejection while making measurements of a set of physical properties of feed, variations of a streaming potential difference across pores of the membrane, variation in pressure differences between an upstream side and a downstream side of the membrane, and concentration differences between the feed and permeate filtered through the membrane.

Abstract: A device which may be carried by and part of an unmanned vehicle which measures characteristics of manure of animals such as dairy cows that are milked and fed in a stable provided for them. The vehicle is supported by three driven wheels and carries a mechanism for analyzing manure which comprises a compression chamber for receiving a manure sample. A sieve is provided on one side of the chamber and a piston forces the manure sample through the sieve. By measuring the pressure required to squeeze the manure sample through the sieve, characteristics such as the fibrousness and the viscosity of the manure sample can be determined. The vehicle also carries an identification instrumentality for identifying the animal that provided the manure sample and may carry a temperature sensor and an inertia meter. It is operatively associated with a computer which registers data provided from analysis of each animal's manure sample and provides same as displayable data.

Abstract: A device for measuring concentration of a flowing suspension wherein a moveable detector body (3) is arranged for detecting the resistance against movement in the suspension, and including a flow modifying element (4) for bringing a portion of the suspension which is representative of the concentration of the suspension flow to the region of the detector element (3). The invention is distinguished by the flow modifying element being a fixed deflector (4), which is arranged to deflect a boundary layer (7) of the suspension flow closest to the conduit wall (1) such that it is brought away from the region of the detector body (3). The invention also concerns a method for measuring concentration and a deflector.

Abstract: The object of the invention is a sampling apparatus in a continuous industrial process for taking a sample of the substance to be monitored. The sampling apparatus is located on the wall of the pulp tank and it includes a sample chamber, which is equipped with a cover, and a filter. The sample chamber includes a closing device, by means of which the connection from the pulp tank to the sample chamber can be closed, as a result of which the filter remains in the sample chamber in the space between the cover and the closing device. The filter can be pulled out of the sample chamber for cleaning after the cover of the sample chamber has been opened. Another object of the invention is a sampling method and a cleaning method for the sampling apparatus presented.

Abstract: The invention si a multiphase flow metering method. The method includes a) determining at least two pressure values P1 and P2 for the different points A and B, and the value of the internal pressure Po of a device; and b) determining, from the values determined in step a) from the knowledge of the density of the gas phase and of the liquid phase and/or of the average value of the density of the multiphase medium in a slotted tube, from a relation connecting at least the following parameters: the level of the interface between the liquid phase and the gas phase and/or the volume ratio of the gas phase to the liquid phase (GLR) from pressure values P1, P2, Po, the total flow rate value Qt of the flowing multiphase medium and/or the flow rate qg, q1 of each of the phases.

Abstract: A biofouling monitor is described which has a column having an inlet and an outlet; a microorganism nutrient feed line located upstream of the inlet; and a first pressure sensor located upstream of the inlet for measuring flow pressure and a second pressure system located downstream of the outlet for measuring flow pressure. Also described is a biofouling monitor which further has a recirculation system and optionally inert packing material located in the column. A method to monitor or detect biofouling ahead of time in an aqueous system is further described.

Abstract: An apparatus for monitoring particulates in a liquid stream and the rate at which the particulates foul a filtering medium, generally a reverse osmosis membrane, to determine at what point in time the filtering medium should be cleaned or replaced. The apparatus includes a monitoring filter unit having a plurality of filter portions. The pressure drop across each filter portion, through which a sample of the feed stream is passed, is monitored. Fouling of a filter portion by accumulated particulate thereon causes an increase in the pressure drop across the filter unit. The increasing pressure drop is monitored as an indicator of the correlative or correspondent fouling of the main filtering medium to be protected. Different filter portions in the filter unit are successively used as each becomes fouled, allowing continuous monitoring for extended periods of time between filter media changes in monitoring filter unit.

Abstract: The invention relates to a method and a microsensor for measurement of transport coefficients like diffusivity or flow velocity. The microsensor has a reservoir provided with a mouth and a transducer. The transducer has a tip placed in the mouth, which can be provided with a membrane or insert. The reservoir contains one or more gases or one or more liquid-dissolved substances intended for the diffusion through the mouth into an area or field of a medium outside the mouth of the reservoir. The transducer measures the partial pressure of the gas or the concentration of the liquid-dissolved substance in the mouth, whereby transport coefficients of diffusivity or flow velocity are determined. Preferably, the gradient of the partial pressure or the concentration is determined.

Abstract: A component is washed with a fluid to release particulate contaminant. The particulate-containing fluid is passed through a screen (22) having a known number of apertures of identical known size. The change in pressure caused by the accumulation of particles in the screen is measured and compared with the pressure when the screen is clean. From this, a control system (54) determines the number of particles in the fluid having a size greater than the aperture size. This is related to a unit volume by measuring the volume of fluid passing through the screen (22). If the screen blocks before all the fluid is passed through the screen (22), the fluid is pulsed in forward and reverse flow to re-distribute the particles on the screen. The fluid is then back washed from the screen to a second screen (28) having a known number of apertures of identical size. The number of particles per unit volume having a size greater than the size of the apertures of the second screen is then determined.

Abstract: A method and apparatus for the controlled instrumentation processing of cells and other particles with a filter device measures a parameter of the flow through the filter device of fluid carrying the particles. A measure of the change of the fluid flow through the filter device yields desired information for quantifying the particles and for quantifying the obstruction of the filter device by the particles. The method and apparatus typically operate automatically.

Abstract: A method of predicting logarithmic reduction values for a membrane filtration system having a filtrate flow portion and a bypass flow portion relative to a filtrate permeable membrane with stable input gas flow comprising: determining the filtrate flow rate through the membrane under the action of an applied test pressure, determining the membrane bypass flow rate using integrity test measurements and estimating the logarithmic reduction value using the ratio of determined filtrate flow rate and determined bypass flow rate. Methods of testing the integrity of a porous membrane are also disclosed.

Abstract: A Coulter apparatus comprises a volumeter assembly containing a conduit through which a particle suspension is caused to pass simultaneously with an electrical current. In preferred embodiments the volumeter assembly comprises at least one traditional Coulter conduit wafer, i.e., a dielectric wafer containing a central circular conduit, and at least two electrically conductive collars. The conductive collars approximate the conduit diameter in thickness, are uninsulated, and are attached to opposite sides of the conduit wafer, the openings being congruent with the Coulter conduit. The Coulter conduit in the dielectric wafer and the openings in the conductive collars collectively form a hydrodynamically smooth conduit, in which the electric and hydrodynamic fields of the Coulter conduit are amended. The electric field is shaped to confine the particle-sensitive zone of the novel volumeter conduit within the conduit's physical boundaries, thereby decreasing the zone's coincidence volume.