Abstract: Detection of miniscule amounts of an analyte is accomplished via multiple bindings of specific materials on a sensor configured to sense mass. The sensor is prepared by immobilizing an antibody to a surface of the sensor, wherein the antibody is known to bind to the analyte. The prepared sensor is exposed to the analyte. The analyte binds to the antibody. The sensor then is exposed to additional antibody, which binds to the analyte. The sensor then can be sequentially exposed to additional antibodies that are known to bind to previously bound antibodies. Each additional binding further increases the effective mass of accumulated material on the sensor. The total effective mass is greater than the mass of the accumulated analyte, thus providing means for detecting extremely minute amounts of analyte. Applications include detection of pathogens and DNA.

Abstract: A change in impedance of a electromechanical resonating sensor is utilized to detect and/or measure a change in mass accumulated on the sensor. The impedance is monitored at a fixed frequency. The fixed frequency may be at or near the resonance frequency of the sensor. In various configurations, the sensor comprises a quartz crystal microbalance sensor or a piezoelectric cantilever sensor.

Abstract: The concentration of a material covering a surface is controlled via an equilibrium process. Equilibrium parameters such as a concentration of the provided material, the exposure time of the material to the surface, and the surface area of an attractor applied to the surface are determined utilizing a millimeter sized piezoelectric cantilever sensor. In an example embodiment, the material is provided at a low concentration to the surface until equilibrium is attained. The amount of material accumulated on the surface is determined utilizing the cantilever sensor. The surface area of the attractor and the measured amount of material are utilized to determine the amount of the attractor surface area having the material bound thereto. Knowledge of the equilibrium parameters allows controlled surface coverage of the material on the attractor for any application. The concentration of the material adsorbed on the surface is precisely determinable and repeatable.

Abstract: A biconically tapered optical fiber serves as a biosensor at all optical wavelengths of interest ranging from UV to far IR at subfemtogram per mL sensitivity. The biconically tapered sensor detects biomaterials such as pathogenic species, proteins and DNA and others biological analytes. Although it uses the principles of evanescent fields, absorption, adsorption, fluorescence capture and retransmission through the fiber, the detection at the sub-nanogram per mL level is achieved primarily by adsorption or a surface activity due to a refractive index change. The geometry of the biconically tapered optical sensor affects its performance. The sensing modality is achieved in situ with a source connected at one end of a tapered fiber and a suitable detector at the other end. The tapered region is optionally immobilized with a recognition molecule such as an antibody to the target antigen or a complementary DNA strand. The sample is brought in contact with the tapered region either in batch mode or in a flow mode.

Abstract: Extremely minute amounts of live pathogens are rapidly detected using a piezoelectric cantilever sensor. A single pathogen is detectable in about 30 minutes. Pathogen-specific antibodies are immobilized on the sensor surface. The sensor is exposed to a medium that potentially contains the target pathogen. When target pathogens are contained in the medium, both dead and live pathogen cells bind to the immobilized antibody on the sensor surface. The attached target pathogen cells are exposed to a pathogen discriminator capable of discriminating between live cells and dead cells by increasing the mass of live cells. Example pathogens include Escherichia coli, Listeri monocytogene, and Salmonella enteritidis. Example antibodies include those that bind to the pathogenic bacteria designated as ATCC 43251, ATCC 700375, and ATCC 31194. Example pathogen discriminators include intracellular pH indicating molecules.

Abstract: Detection of miniscule amounts of nucleic acid is accomplished via binding of target nucleic acid to probe material, composed of nucleic acid, which is bound to a sensor configured to sense mass. The sensor is prepared by immobilizing a probe material to a surface of the sensor, wherein the probe material is known to bind to the target nucleic acid. The prepared sensor is exposed to the target nucleic acid. The target nucleic acid binds to the probe material. The mass accumulated on the sensor reflects the amount of target nucleic acid bound to the probe material.

Abstract: Quantification of a target analyte is performed using a single sample to which amounts of the target analyte are added. Calibration is performed as part of quantification on the same sample. The target analyte is detectable and quantifiable using label free reagents and requiring no sample preparation. Target analytes include biomarkers such as cancer biomarkers, pathogenic Escherichia coli, single stranded DNA, and staphylococcal enterotoxin. The quantification process includes determining a sensor response of a sensor exposed to the sample and configured to detect the target analyte. Sensor responses are determined after sequential additions of the target analyte to the sample. The amount of target analyte detected by the sensor when first exposed to the sample is determined in accordance with the multiple sensor responses.

Abstract: Detection of miniscule amounts of an analyte is accomplished via multiple bindings of specific materials on a sensor configured to sense mass. The sensor is prepared by immobilizing an antibody to a surface of the sensor, wherein the antibody is known to bind to the analyte. The prepared sensor is exposed to the analyte. The analyte binds to the antibody. The sensor then is exposed to additional antibody, which binds to the analyte. The sensor then can be sequentially exposed to additional antibodies that are known to bind to previously bound antibodies. Each additional binding further increases the effective mass of accumulated material on the sensor. The total effective mass is greater than the mass of the accumulated analyte, thus providing means for detecting extremely minute amounts of analyte. Applications include detection of pathogens and DNA.

Abstract: The techniques described herein are directed to removing material that has attached to or preventing material from attaching to the surface of a piezoelectric cantilever. The material can be a target material, other, non-target, material that may be weakly bound or attached to the cantilever sensor, or the material may be a combination thereof. Accordingly, the cantilever sensor can be reused, in situ, without degraded detection performance of the cantilever sensor. The techniques may also be utilized to remove all material that has attached to a surface of the cantilever sensor which provides means for reusing the cantilever sensor.

Abstract: Flow cells configured for piezoelectric millimeter-sized cantilever sensors provide direct, sensitive detection of analytes in fluid media. The flow cells comprise a flow inlet and a flow outlet positioned to cause sample flow past a sensing surface of the cantilever sensor. The flow cell is configured for millimeter-sized cantilever sensors. The geometry of the flow cell influences the sample flow and thus the interaction of the flow with the cantilever sensor.

Abstract: A piezoelectric cantilever sensor includes a piezoelectric layer and a non-piezoelectric layer, a portion of which is attached to the piezoelectric layer. In one embodiment, one end of the non-piezoelectric layer extends beyond the end of piezoelectric layer to provide an overhang. The overhang piezoelectric cantilever sensor enables increased sensitivity allowing application of the device in more viscous environments, such as liquid media, as well as application in liquid media at higher flow rates than conventional piezoelectric cantilevers. In another embodiment, the sensor includes first and second bases and at least one of the piezoelectric layer and the non-piezoelectric layer is affixed to each of the first and second bases to form the piezoelectric cantilever sensor. In this embodiment, the sensor is robust and exhibits excellent sensing characteristics in both gaseous and liquid media, even when subjected to relatively high flow rates.

Abstract: Molten metal containing suspended liquid particles is passed preferably generally upwardly through a porous media so constructed and arranged such that the movement of the molten metal therethrough renders the suspended liquid particles gravity separable. The gravity separable liquid particles rise upwardly or settle downwardly so as to be removable from said molten metal for subsequent removal therefrom. An associated apparatus is also provided.

Abstract: A filter system for removing solid impurities from molten metal is described comprising a housing containing vertically disposed rigid coarse filter facing the incoming flow of molten metal and capable of removing solids having a particle size of at least 10 microns and a rigid fine filter mounted vertically behind the coarse filter and capable of removing solids having a particle size as small as 1 micron. The apparatus further includes a heater for maintaining the temperature of the molten metal and a sparger mounted adjacent the front face of one filter to provide an intermittent gas flow over the face of the filter to dislodge solids on the filter as filter cake. In a preferred embodiment, the rigid filters are nested cylinders, and the molten metal is directed to the center of the smaller coarse filter cylinder from which it then flows through the coarse filter outward to and through the fine filter cylinder and then from the fine filter out of the filter housing.