Abstract: An oil change sensing system for an internal combustion engine, having an oil pressure sensor adapted to provide an oil pressure signal to an engine control module; an oil temperature sensor adapted to provide an oil temperature signal to the engine control module; wherein the engine control module comprises an algorithm which determines the oil's viscosity by using the measured oil temperature and oil pressure and the determined oil viscosity and a fresh oil viscosity are used to determine whether the oil is in a preferred operating range.

Abstract: A method and apparatus for studying the properties of a fluid are provided in which in which a rheometer is used to obtain, for example, value(s) indicative of the shear stress in the fluid to thereby obtain a set of data. The data is then directly compared using, for example, multivariate analysis, with previously obtained data corresponding to a fluid(s) with known rheological properties. The results of this comparison can then be used, for example, to control a manufacturing process.

Abstract: A rheometer has a rotor comprising a shaft which is seated with play in a recess of a bearing block and is supported contact-free in a radial and/or axial direction by an external air cushion which acts in a bearing section. To provide for simple and inexpensive production of an air bearing having a high loading capacity, the wall of the recess in the bearing section is continuous without bore-holes, and consists of air-permeable material. The bearing air loads the side of the wall facing away from the shaft and penetrates through the wall.

Abstract: An apparatus for testing properties of materials under operating conditions of the materials. The apparatus includes a hermetically sealed vessel in which a tribology tester is mounted. The tribology tester includes a pair of lever arms having first and second ends with the first end of each lever being pivotally connected. A spring is located between the second end of each of the lever arms with a test block assembly being mounted between the lever arms in a position between the pivotal connection and the spring. The test block assembly includes a pair of test blocks and a pin with the spring biasing the test blocks into contact with the pin. Drive means, such as a motor, is magnetically coupled to the tribology tester to rotatively drive the pin against the test blocks to test the properties of the materials.

Abstract: Activation energy, W, is determined from oil conductivity measurements to thereby provide engine oil condition from a known relationship between viscosity and W. Changes of W at a given temperature as the oil ages are reflective of changes in viscosity of the oil at the same given temperature, wherein changes in W at different temperatures are reflective of changes of viscosity at those respective temperatures as the oil ages. To determine viscosity, the temperature dependence of the oil's conductivity is measured to deduce the value of W at a given temperature. W is monitored as the oil ages. W may also be determined through the ratio of the oil conductivities at two different temperatures by techniques well known in the art by which the viscosity may be determined as the oil ages.

Abstract: The present invention is an apparatus and method for analyzing a fluid used in a machine or in an industrial process line. The apparatus has at least one meter placed proximate the machine or process line and in contact with the machine or process fluid for measuring at least one parameter related to the fluid. The at least one parameter is a standard laboratory analysis parameter. The at least one meter includes but is not limited to viscometer, element meter, optical meter, particulate meter, and combinations thereof.

Abstract: An oil change sensing system for an internal combustion engine, having an oil pressure sensor adapted to provide an oil pressure signal to an engine control module; an oil temperature sensor adapted to provide an oil temperature signal to the engine control module; wherein the engine control module comprises an algorithm which determines the oil's viscosity by using the measured oil temperature and oil pressure and the determined oil viscosity and a fresh oil viscosity are used to determine whether the oil is in a preferred operating range.

Abstract: The present invention relates to a method for determining parameters for the viscosity or temperature of a brake fluid of a vehicle which is supplied to the wheel brakes by way of a motor-and-pump assembly equipped with actuatable valves and a hydraulic unit, with which an electronic control unit is associated. To ensure a high degree of control dynamics even at low temperatures, it is suggested that the temperature of the hydraulic unit is measured by way of a temperature-sensitive element which connects the motor-and-pump assembly to the electronic control unit, and the parameters are determined by way of the temperature of the hydraulic unit.

Abstract: Methods to predict the rheological properties of composition comprising a filler in a matrix are described. The present invention further involves determining the difference between the work of cohesion and the work of ahhesion for a filler and a matrix in order to quantitatively predict the rheological properties of the system, such as yield point. The ability to predict such properties has numerous advantages. The present invention further relates to a rheological master curve and a method to produce the curve which permits one to predict a Theological property of a composition comprising a filler in a matrix based on the particular polymer used and the particular filler used. Also disclosed is a method of method of choosing a filler to achieve a desired rheological property using the theological master curve described herein.

Abstract: A method for determining the viscosity of a fluid flowing through a system at any point in the system whereby the method involves determining a characteristic relationship for the fluid between viscosity and shear rate; obtaining a shear rate of the fluid as it moves through at least one position in the system; and determining the viscosity of fluid at the at least one position by applying the shear rate to the characteristic relationship. Where the system is the circulatory system of a living being, the method includes determining a viscosity-shear rate relationship unique to that individual. Furthermore, the method further entails determining the actual viscosities and shear rates being experienced in selected blood vessels of the living being.

Abstract: System and methods are described for dynamically controlling operation of a rheometer. A program is created on a programming interface for executing a test upon a sample in a rheometer by receiving user selections of a plurality of nodes and connections of each node to another node according to directional connection indicators. Nodes indicate steps for performing a test upon a sample or configuring a rheometer for performing a test upon a sample. Scripts are created for generating a sequence of instructions to the rheometer. The scripts include instructions for performing steps indicated by each of the selected nodes and in accordance with the directional connection indicators. Low-level instructions are downloaded from the scripts for execution in the rheometer, and drivers in the rheometer are instructed for performing the downloaded instructions.

Abstract: A method for assessing the deterioration of motor oil is provided, in which the oil viscosity of the motor oil is measured by a sensor, and the length of an oil-change interval is determined in an evaluating electronics having a display device. According to the present invention, it is provided that a temperature sensor for the simultaneous determination of the oil temperature is assigned to the sensor for measuring the oil viscosity, and the oil viscosity and oil temperature are measured in the cooling phase of the engine after it has been switched off.

Abstract: Device for direct refrigeration has heat-conductable solid member with refrigerant passageway coursing through or about; and at least one test sample well in or in proximity to it, at least one solid, heat-generating member affixed or in proximity to it; and/or optional component(s) and/or feature(s). Heat-conductable solid member may have opposing refrigerant flowpaths containing conventional cooling material(s), for example, air, liquid methanol or ethylene glycol, but preferably, refrigerant for direct refrigeration. The member may be, for example, a block of copper and/or other material with a high heat-conductance, with one or more test sample well(s) for insertion of test sample cell(s) for low-temperature rotary viscometric yield stress testing of engine oils, or other testing. Heating may be employed. Dynamic temperature control can be facilitated by temperature sensor and/or controller system, with sensor(s) and/or heating element(s) strategically placed in or on the block.

Abstract: A method of evaluating engine oil wear on the basis of viscosity measurement, accounting for the addition of fresh oil. Using an oil viscosity sensor, an amount of fresh oil added is detected, then the oil viscosity sensor determines a viscosity of the oil mixture of the engine oil and fresh oil. A quantity of fresh oil added is determined in the electronic analyzer from a difference between the old oil level, i.e., the oil volume, and the new oil level. The viscosity of the fresh oil is determined from the viscosity of the old engine oil immediately before the point in time of the addition of fresh oil and from the viscosity after the addition. A hypothetical initial viscosity is calculated as a new corrected reference value from the known value of the viscosity of the old engine oil in the new condition, the quantity of the engine oil still present at the point in time of the addition, the calculated viscosity of the fresh oil and the calculated quantity of the fresh oil.

Abstract: The present invention provides systems and methods for screening a library of material samples for a rheological property such as viscosity or elasticity. Accordingly, a library of material samples is can be provided in a substantially liquid form. The library is contacted with at least one probe for applying a stimulus to the material samples such as by moving the at least one probe within the samples. A response such as resistance to the motion of the probe is monitored and can be related to a rheological property of the samples.

Abstract: A system for measuring oil condition in large engines includes a bypass valve that is installed in a lubrication system along a fluid line between an oil pan and an engine. The bypass valve communicates with a measurement chamber and when energized by a control module, the bypass valve diverts oil from the lubrication system to the measurement chamber. An oil condition sensor is disposed within the measurement chamber and is used to determine the condition of the oil that is diverted to the chamber. After the condition of the oil is determined, the bypass valve is energized to release the oil from the measurement chamber back into the lubrication system.

Abstract: A blood viscosity measuring system and methods for measuring blood viscosity monitors the change in height of one of two, oppositely-moving, columns of blood from the circulating blood of a patient and, given the dimensions of a capillary tube through which the blood flows and by detecting a single blood position of the other oppositely-moving column, determines the blood viscosity over a range of shears, especially low shears. The system includes a tube set (disposable or non-disposable) that includes a pair of riser tubes, a capillary tube of predetermined dimensions that is coupled between the riser tubes (or that forms a portion of one riser tube) and a valve mechanism for controlling the circulating flow of blood from the patient into the riser tubes.

Abstract: The present invention provides a method and device for determining the viscosity of motor oil in an internal combustion engine comprising: measuring frictional torque of the engine based on engine data, such as, the clutch switch signal which shows whether the clutch is engaged transmitting torque to the drive train; a generator load signal, a starter load signal, acceleration power consumption, and the like.

Abstract: A device for determining the viscosity of a liquid has a temperature sensor and a heater disposed in spaced relation within a channel. When the device is immersed in a liquid, the heater heats the liquid and the temperature sensor detects the change in temperature of the liquid in response to heating of the liquid by the heater. A controller coupled with the temperature sensor receives a signal corresponding to the temperature of the liquid and determines an index value corresponding to the change in temperature with respect to time. The index value may be compared with a stored value to evaluate the relative change in viscosity, or it may be used to determine an actual value of viscosity of the liquid.

Abstract: A viscosity testing and stirring device includes a rigid, elongated member having a viscosity testing opening defined therethrough. In one embodiment, the member has a generally V-shaped cross-section along at least a portion of its length. In another embodiment, the member has a tear-drop shaped opening. In yet another embodiment, the member has a non-flat cross-section along at least a portion of its length. The member functions as a stirrer and the opening is used to test the viscosity of a liquid. A method for testing the viscosity of a liquid is also provided.

Abstract: A method and device for determining fluidity of fluid in a pack that is moving without breaking and opening the pack by locating at least two measurement points on the surface of the pack filled with the fluid, measuring the surface temperatures of the measurement points by non-contact type temperature sensors, and managing the measured values using an arithmetic control unit.

Abstract: An indication of the elasticity of a non-Newtonian fluid is obtained by extending a fluid bridge between a pair of relatively movable surfaces that hold a fluid sample therebetween, and continuing a timewise progression of separation between two opposed moveable surfaces in a controlled manner until the displacing extension is great enough to cause a break point in the fluid sample. The extension of a fluid bridge at the break point is determined and used as an indication of elasticity.

Abstract: Apparatus and methods for evaluating the rheological properties of Newtonian and non-Newtonian liquids and melts employs the principle of capillary breakup following rapid stretching of the fluid between two plates. The apparatus includes opposed surfaces defining a sample site disposed therebetween. A liquid sample undergoes an extensional deformation between the opposed surfaces which separate using a user-defined motion profile. The time profile of the diameter of the liquid filament is monitored and recorded as a function of time. Preferred embodiments of the present invention include data analysis of the diameter of the filament as a function of time which provides information regarding rheological parameters including, but not limited to, extensional viscosity versus strain.

Abstract: The invention provides a method for operating a controlled stress rheometer in a controlled strain mode to follow a demand strain Xd in a sample having applied thereto a variable demand force Td, inducing an actual strain X including the steps of: monitoring the actual strain X; continuously comparing the actual strain X with the demand strain Xd and calculating the difference; calculating in real time, using an appropriate algorithm, the value of Td necessary to adjust the strain from X to Xd, and adjusting Td to the calculated value so as to effect this strain adjustment. The method may be performed by a computer software algorithm installed in a digital signal processor forming part of the controller system of the rheometer.

Abstract: A drilling mud monitoring system includes a single measurement chamber which is filled with a predetermined quantity of drilling mud. The chamber is weighed to provide a value representative of the density of the drilling mud. The time needed for the chamber to drain is measured to provide a value representative of viscosity. The system proceeds through a measurement cycle in which the chamber is filled, weighed, timed and washed. At the end of the wash step, the weight of the chamber is compared with an empty weight and if the chamber weighs too much, the conclusion is that drilling mud adheres to the chamber so it is washed again. An alarm is sounded if the mud weight is too low and/or too high or in the case of a machine malfunction.

Abstract: A method and apparatus for measuring the rheological properties of a polymer melt includes flowing the polymer melt from a first reactor to a device through a conduit at a predetermined flow rate, measuring a first pressure of the polymer melt at a first location in the conduit, measuring a second pressure at a second location downstream from the first location, measuring a temperature at a third location in the conduit, wherein the third location is between the first location and the second location, and calculating the rheological property of the polymer melt as it flows through the conduit. The method and apparatus do not require diversion of the polymer melt from the main process stream.

Abstract: A system and method for measuring viscosity, melt flow index (MFI), and melt volume rate (MVR) of a polymer melt in real-time during an extrusion process to provide quick and accurate feedback for process control. The system includes a polymer processing rate sensor (36), a polymer melt temperature sensor (30), an extruder pressure sensor (32), and a die head temperature sensor (34) for taking in-line measurements during the extrusion process. The in-line measurements are made on the main process stream of the polymer melt, with the determination of viscosity, MFI, and MVR based on these measured values and those obtained during a calibration run with polymers having known properties. The invention can be used in any polymer compounding and extrusion process utilizing die opening with any constant geometry for monitoring quality and providing feedback for process control.

Abstract: A method for obtaining the viscosity of the circulating blood of a living being using an adulterated blood sample and a correlation factor obtained from a circulating blood viscometer.

Abstract: A process for determining changes in a liquid medium, in particular a liquid coating agent or its components, caused by shear stress, in which a given volume of the medium is allowed to pass repeatedly through a shear unit under reproducible conditions.

Abstract: A system and method for measuring viscosity, melt flow index (MFI), and melt volume rate (MVR) of a polymer melt in real-time during an extrusion process to provide quick and accurate feedback for process control. The system includes a polymer processing rate sensor (36), a polymer melt temperature sensor (30), an extruder pressure sensor (32), and a die head temperature sensor (34) for taking in-line measurements during the extrusion process. The in-line measurements are made on the main process stream of the polymer melt, with the determination of viscosity, MFI, and MVR based on these measured values and those obtained during a calibration run with polymers having known properties. The invention can be used in any polymer compounding and extrusion process utilizing die opening with any constant geometry for monitoring quality and providing feedback for process control.

Abstract: The oil quality used in a machine, vehicle or system can be determined in response to determining a temperature and pressure within an oil supply. Once the oil quality is determined, an oil quality warning light can be activated, indicating the need to change the oil.

Abstract: The present invention provides a single-use electronic device and test card for use therein which performs a coagulation or lysis assay of a blood or plasma sample. The device includes a housing having an exterior surface and defining an interior area and means for receiving the sample through the housing into the interior space. A non-porous substrate is positioned within the interior space for receiving the sample thereon. Preferably, a reagent accelerates the coagulation of the sample and is positioned on the substrate and in contact with the sample. An electroactive species is added to the sample. The device also measures the impedance of the sample and generating an electrical signal which correlates to a curve of the coagulation/lysis assay. Optionally, the electrical signal is received and converted into a digital output corresponding to the coagulation/lysis assay using assay calibration information stored therein. The digital output can be displayed external to the housing.

Abstract: An apparatus and a method for determining the viscosity of a fluid includes an electrical rotary drive (2) with a stator (3), which has a stator winding (4), and with a rotational body (5) which can rotate in the fluid (1). The rotational body (5) is designed as a rotor (5) of the rotary drive (2) and is magnetically journalled in a contact-free manner with respect to the stator (3).

Abstract: This invention relates to a method of measuring a rheological property of a composite filled with particles, and evaluation equipment, in which in situ measurement is performed of the rheological property of a composite filled with particles obtained by mixing a particulate material as raw material with a liquid material, in a condition with the original material structure maintained, without destroying the material by applying external force such as shearing force thereto, comprising a step of measuring the coagulation structure of the particulate material within the composite filled with particles as an anisotropy signal, and a step of employing the amount of this anisotropy as an index of the rheological property value of the composite.

Abstract: A method of evaluating engine oil wear on the basis of viscosity measurement, taking into account the addition of fresh oil is described.

Abstract: Workstation, apparatuses and methods for the high-throughput synthesis, screening and/or characterization of combinatorial libraries. The invention relates to an array, which permits various high-throughput methods for synthesis, screening and/or characterization in the same array, without requiring sample transfer from the array. In a preferred embodiment, the synthesis, screening, and/or characterization steps are carried out in a highly parallel fashion, where more than one compound is synthesized, screened, and/or characterized at the same time. The invention may be practiced at the microscale. The array may comprise thermal channels, for regulating the temperature of the wells in the array. The wells of the array may comprise a membrane, which is used in various screening and characterization methods. The invention also relates to a covered array, comprising the array and an array cover, as well as an apparatus comprising the array, which comprises the array, an array cover and a stage.

Abstract: A scanning rheometer is presented for the rheological property measurement of electrorheological (ER) and magnetorheological (MR) fluids using a non-linear viscoplastic model, based on the fluid height variation with respect to time. The rheometer basically includes a static (e.g., an overhead reservoir) or a dynamic source of fluid, a channel or slit whose sides form electrodes which are in contact with the flowing ER fluid, or a capillary tube exposed to a static/alternating magnetic field for flowing MR fluids, a transfer tube, either one or two riser tubes, and a column level detector for monitoring the column of fluid as it moves in one of the riser tubes. The column level detector is coupled to a processor which analyzes, among other things, column height vs. time data to determine both viscosity and yield stress. The rheometer overcomes one of the major drawbacks of the conventional rheometer: the inability to produce the yield stress of the ER, or MR, fluid in an absolute zero shear rate range.

Abstract: A method to maintain magnetic levitation that is stabilized by means of Hall effect sensors is disclosed. The method and device comprising a Hall effect sensor or sensors used to control an electromagnet to maintain the position between two magnets or objects. The present invention has been used to suspend a magnet in a high pressure tube that is magnetically coupled to a magnet outside the tube connected to an analytical balance that can accurately measure the force on the magnet inside the tube. This force measurement can be used to determine fluid density, flow, viscosity, and solubility. This magnetic levitation method also has application for other devices such as motors, generators, trains, turbines, wind tunnels, and entertainment devices.

Abstract: To measure characteristics of a non-Newtonian fluid, preferably blood, a non-magnetic container is provided for receiving the fluid. A magnetic body is contained in the container, and a winding is provided around the container. An AC current supplying device is connected to the winding for supplying input AC current of different amplitudes thereto to generate magnetic fields of different strengths in the container to cause the magnetic body to oscillate at different shear rates in the fluid. A measuring device is provided for measuring amplitude and/or phase of the oscillations of the magnetic body and a shear rate determining device is provided for determining the shear rates by measuring differences between the amplitude and/or phase of the oscillations of the magnetic body and the amplitude and phase of the input AC currents.

Abstract: A method for measuring the viscosity of a green compact sample includes the steps of finding a corrected value V′ of the sample volume of the green compact sample, where the corrected value V′ of the sample volume is a volume occupied by the inorganic powder in the green compact sample; finding a corrected value (dh/dt)′ of the sample deformation rate of the green compact sample, where the corrected value (dh/dt)′ of the sample deformation rate is the difference between the apparent sample deformation rate and the sample deformation rate due to sintering shrinkage; separating a temperature range X in which sintering shrinkage dominates and a temperature range Y in which plastic deformation dominates with respect to the displacement of the green compact sample; substituting the corrected value V′ of the sample volume for the sample volume V and substituting the corrected value (dh/dt)′ of the sample deformation rate for the sample deformation rate dh/dt in the Gent equation

Abstract: A method for determining oil viscosity includes measuring an oil viscosity parameter value while an oil pump pumps oil through an engine lubrication system. Thereafter, the oil viscosity parameter value is compared to a stored look-up table of oil viscosity parameter values versus oil viscosity values and the viscosity of the oil contained within the vehicle lubrication system is interpolated from the table. The look-up table is generated by installing the pump in a test system and then, measuring the oil viscosity parameter value as the pump pumps oils of known viscosities. For increased accuracy, the look-up table is generated for several temperatures within the range of normal engine operating temperatures and several pump speeds within the range of normal operating pump speeds.

Abstract: The present invention is an apparatus and method for analyzing a fluid used in a machine or in an industrial process line. The apparatus has at least one meter placed proximate the machine or process line and in contact with the machine or process fluid for measuring at least one parameter related to the fluid. The at least one parameter is a standard laboratory analysis parameter. The at least one meter includes but is not limited to viscometer, element meter, optical meter, particulate meter, and combinations thereof.

Abstract: An apparatus and method for determining the viscosity of a fluid over plural shear rates caused by a decreasing pressure differential by monitoring the movement of the fluid through a riser tube and a capillary tube. The movement can be monitored by detecting the changing weight of the fluid, using a precision balance or load cell, as it moves through the riser tube and capillary tube into a fluid collector; or, alternatively, the movement can be monitored by detecting the changing level of a fluid column in the riser tube using a column level detector. A processor then uses the changing weight or height data, along with the dimensions of the capillary tube and a dimension of the riser tube, to determine the viscosity of the fluid. In addition, apparatus and methods for determining fluid viscosity online and fluid mixture homogeneity online are also described.

Abstract: A scanning rheometer is presented for the Theological property measurement of electrorheological (ER) and magnetorheological (MR) fluids using a non-linear viscoplastic model, based on the fluid height variation with respect to time. The rheometer basically includes a static (e.g., an overhead reservoir) or a dynamic source of fluid, a channel or slit whose sides form electrodes which are in contact with the flowing ER fluid, or a capillary tube exposed to a static/alternating magnetic field for flowing MR fluids, a transfer tube, either one or two riser tubes, and a column level detector for monitoring the column of fluid as it moves in one of the riser tubes. The column level detector is coupled to a processor which analyzes, among other things, column height vs. time data to determine both viscosity and yield stress. The rheometer overcomes one of the major drawbacks of the conventional rheometer: the inability to produce the yield stress of the ER, or MR, fluid in an absolute zero shear rate range.

Abstract: A process for evaluating the quality of a printing ink is provided, wherein a defined quantity of the printing ink is stirred; a force or torque to be applied during the stirring is measured, and a defined quantity of moistening agent is added to the ink at a defined point in time. A device for evaluating the quality of the printing ink is also provided with a container for the printing ink; a stirring device, with which an ink filled into the container can be stirred; a measuring device for measuring the force to be applied by the stirring device or the torque to be applied; a moistening agent supply and a control, which actuates the feed of moistening agent such that a predetermined quantity of moistening agent is introduced into the container at a defined point in time.

Abstract: A combined oil quality and fuel contamination sensing system includes a capacitive dielectric sensor and pressure sensing arrangements for measuring the dielectric constant of the oil and the pressure of the oil, respectively, with the oil pressure being indicative of oil viscosity and contamination. The sensors take measurements as oil flows through an internal combustion engine and provide an indication of the cause of a problem with oil in an engine. The system may also include a microcomputer and circuitry for generating an indication of dielectric constant and circuitry for generating an indication of the presence of contaminants within the engine. The system may also include an additional sensor measuring the temperature of oil within the system to adjust oil dielectric constant and viscosity indications. The capacitive dielectric sensor constitute the principal restriction in the flow path between an input high pressure sensing port and an outlet low pressure port.

Abstract: A method for measuring the viscosity of a green compact includes the steps of finding a corrected value V′ of the sample volume of the green compact, where the corrected value V′ of the sample volume is a volume occupied by the inorganic powder in the green compact; finding a corrected value (dh/dt)′ of the sample deformation rate of the green compact, where the corrected value (dh/dt)′ of the sample deformation rate is the difference between the apparent sample deformation rate and the sample deformation rate due to sintering shrinkage; separating a temperature range X in which sintering shrinkage dominates and a temperature range Y in which plastic deformation dominates with respect to the displacement of the green compact; substituting the corrected value V′ of the sample volume for the sample volume V and substituting the corrected value (dh/dt)′ of the sample deformation rate for the sample deformation rate dh/dt in the Gent equation with respect to the temperature ran

Abstract: A drilling mud monitoring system includes a single measurement chamber which is filled with a predetermined quantity of drilling mud. The chamber is weighed to provide a value representative of the density of the drilling mud. The time needed for the chamber to drain is measured to provide a value representative of viscosity. The system proceeds through a measurement cycle in which the chamber is filled, weighed, timed and washed. At the end of the wash step, the weight of the chamber is compared with an empty weight and if the chamber weighs too much, the conclusion is that drilling mud adheres to the chamber so it is washed again. An alarm is sounded if the mud weight is too low and/or too high or in the case of a machine malfunction.

Abstract: A piezoelectric crystal element and a sensor utilizing the same are presented for use in a sensor device for identifying at least one foreign material from environment. The crystal element comprises at least one crystal resonator in the form of an inverted mesa structure, which has a membrane-like region and is characterized by a certain resonance frequency value. A surface region of the crystal resonator is modified by reactive molecules of a kind capable of interacting with the foreign material to yield a reaction product that effects a change in the resonance frequency of the crystal resonator from said certain resonance frequency value. This change is indicative of the identity and quantity of the foreign material.

Abstract: The invention relates to a method and measuring apparatus for measuring freeness. Freeness is measured with the help of an automatic data processing apparatus (30) so that the flow rate of a liquid draining from a measuring chamber (10) is measured using the measuring apparatus (12) until the flow rate is equal to or lower than a predefined flow rate.