Patent Description:
The present invention relates generally to a piezoelectric air pump, and, more particularly, to a miniature piezoelectric air pump to generate pulsation-free air flow for pipette apparatus proximity sensing.

Various types of analytical tests related to patient diagnosis and therapy can be performed by analysis of a liquid sample taken from a patient's bodily fluids, or abscesses. These assays are typically conducted with automated clinical analyzers onto which tubes or vials containing patient samples have been loaded. The analyzer extracts a liquid sample from the vial and combines the sample with various reagents in special reaction cuvettes or tubes (referred to generally as reaction vessels). Usually the sample-reagent solution is incubated or otherwise processed before being analyzed. Analytical measurements are often performed using a beam of interrogating radiation interacting with the sample-reagent combination, for example, turbidimetric, fluorometric, absorption readings, or the like. The measurements allow determination of end-point or rate values from which an amount of analyte related to the health of the patient may be determined using well-known calibration techniques.

Some analyzers and certain pipetting apparatuses rely on the Bernoulli principle to sense objects such as disposable tips and liquid free surfaces in the automated processes associated with liquid sample testing. To sense an object using the Bernoulli principle, the sample probe must have a continuous supply of air flowing through it. As the sample probe nears an object, a pressure transducer senses the conversion of the supply flow's kinetic energy to potential energy. Because the sensing algorithms must detect the supply flow's conversion of kinetic energy to potential energy for object detection, of pressure pulsations must be minimized.

One current method which relies on the Bernoulli principle includes a rotary vane pump to supply air to the probe during object sensing. As each vane passes the ports in the pump housing, large pressure pulsations are created. Pumps with one or more internal valves to control the direction of flow may also produce pulsated air flow. An external pulsation dampener is sometimes used to condition pressure spikes and smooth the supply flow to the sample probe. Smooth and steady flow is required for the control system to reliably detect if a sample probe is approaching an object.

Although some conventional systems attempt to address the problem of generating a pulsation-free flow, they are generally not cost effective. For example, <CIT> describes an automatic control system for sensing and controlling liquid surface levels utilizing a vertically movable nozzle which issues a fluid downwardly in a stream against the surface being sensed. However, the disclosure only mentions that a constant pressure supply is needed and does not describe how to generate smooth and steady air flow. <CIT> describes another current method in an apparatus for aspirating and dispensing sample fluids. To achieve a steady and smooth supply of air flow at the distal end of the probe, a pulsation damper in the form of coiled tubing or a serpentine block, and a vent tube are needed. This addition of the pulsation damper complicates the assembly and adds unnecessary cost. <CIT> discloses a suction-discharge device which is part of an automated analyzer and a method for drawing a biological sample using such a device. The device comprises means causing a pressure variation and/or air flow which corresponds to an idle state of the device, and means for detecting a difference in pressure which corresponds to the position in which the lower free end of the device is located, relative to the surface of the sample. The air flow may be generated, inter alia, by a piezoelectric system capable of pumping air. <CIT> teaches an apparatus which detects the presence or absence of a tip in an automated pipette. The apparatus comprises means for moving down and up, relative to the surface of a liquid sample, a conduit to which a tip is engaged. It further comprises means for generating pressure waves which are directed into the conduit for establishing acoustic impedance therein, and a detector for detecting the acoustic impedance level when the open end of the tip is in an open condition, an open but constricted condition or has contact with a fluid surface. The acoustic transducer may be a piezoelectric crystal.

The present disclosure is directed to overcoming this and other problems of the prior art.

Embodiments of the present invention address the problems of the prior art with a sample probe system according to claim <NUM>. This sample probe system comprises an air supply system having a piezoelectric pump that may be used in conjunction with a sample probe system in order to perform proximity or location sensing of a sample probe while providing smooth, laminar flow in a cost-effective and compact manner. Further preferred aspects of the invention are defined in the dependent claims.

The sample probe system includes a sample probe assembly, an air supply assembly, and a control system. The sample probe assembly includes a transducer and a sample probe. The air supply assembly includes a piezoelectric pump configured to supply an air flow to the sample probe assembly such that the air flow exits the sample probe. The piezoelectric pump is an ultrasonic pump which receives an input voltage at a frequency of greater than <NUM>. The control system determines a relative location of the sample probe based on pressure changes in the air flow detected by the transducer.

In other embodiments, a sample probe system includes a sample probe assembly, an air supply assembly, and a control system. The sample probe assembly includes a transducer and a sample probe. The air supply assembly includes a piezoelectric pump configured to supply an air flow to the sample probe assembly such that the air flow exits the sample probe. The piezoelectric pump includes an outer housing comprising an inlet opening and an outlet nozzle, an intake channel defined in the outer housing fluidly connected to the inlet opening, an inner pump positioned in the outer housing and configured to draw air in from the intake channel and expel air out of the outlet nozzle to produce the air flow to the sample probe assembly, the inner pump including a piezoelectric element. The control system applies a voltage to the piezoelectric element in order to produce the air flow and determine a relative location of the sample probe based on pressure changes in the air flow detected by the transducer.

In other embodiments, a chemical analyzer includes a reaction carousel configured to support a plurality of containers, a sample fluid tube transport system for transporting sample fluid tubes, a liquid sampling probe configured to aspirate and dispense portions of sample fluid from the sample fluid tubes to the plurality of containers supported by the reaction carousel, and a control computer configured to perform automated control operations within the chemical analyzer. The liquid sampling probe includes a sample probe assembly and an air supply assembly. The sample probe assembly includes a transducer and a sample probe. The air supply assembly includes a piezoelectric pump configured to supply an air flow to the sample probe assembly such that the air flow exits the sample probe. The control computer is configured to determine a relative location of the sample probe based on pressure changes in the air flow detected by the transducer.

The foregoing and other aspects of the present invention are best understood from the following detailed description when read in connection with the accompanying drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments that are presently preferred, it being understood, however, that the invention is not limited to the specific instrumentalities disclosed. Included in the drawings are the following Figures:.

Embodiments of the present disclosure include a piezoelectric pump incorporated into a sample probe system. The piezoelectric pump produces pulsation-free air flow and thus allows a control system to reliably detect a location of a sample probe using the Bernoulli principle. In some embodiments, the piezoelectric pump operates without any internal valves, as such valves may cause turbulence or otherwise non-laminar flow. The piezoelectric pump may operate through periodic or aperiodic oscillations of a piezoelectric material. The sample probe system may further include feedback control of the piezoelectric pump, thereby allowing the system to compensate for manufacturing biases or altitude and/or providing a feedback system which can alert a user that there is a problem, such as the need for a filter change or if a clog is present.

<FIG>, taken with <FIG>, shows schematically the elements of an automatic chemical analyzer <NUM> in which the present invention may be advantageously practiced, which may include, for instance the chemical analyzer described in <CIT>. Analyzer <NUM> comprises a reaction carousel <NUM> supporting an outer carousel <NUM> having cuvette ports <NUM> formed therein and an inner carousel <NUM> having vessel ports <NUM> formed therein, the outer carousel <NUM> and inner carousel <NUM> being separated by an open groove <NUM>. Cuvette ports <NUM> are adapted to receive a plurality of reaction cuvettes <NUM>, as seen in <FIG>, that contain various reagents and sample liquids for conventional clinical and immunoassay assays. Vessel ports <NUM> can be adapted to receive a plurality of reaction vessels <NUM>, as shown in <FIG>, that contain specialized reagents for ultra-high sensitivity luminescent immunoassays. While cuvettes and reaction vessels can have differing shapes, as used herein, the methods for mixing can be applied to the contents of reaction vessels <NUM> or cuvettes <NUM>, and the terms reaction vessels and cuvettes should be considered broadly and interchangeably. Reaction vessels can include, for instance, cuvettes, vials, tubes, or other suitable vessels for mixing reagents and solutions.

Reaction carousel <NUM> is rotatable using stepwise movements in a constant direction, the stepwise movements being separated by a constant dwell time during which reaction carousel <NUM> remains stationary and computer controlled assay operational devices <NUM>, such as sensors, reagent add stations, mixing stations, and the like, operate as needed on an assay mixture contained within a cuvette <NUM>.

Analyzer <NUM> is controlled by software executed by a computer <NUM> for performing assays conducted by various analyzing means <NUM> (e.g., detection units) within analyzer <NUM>. Analyzing means can include, for instance, one or more photometers, turbidimeters, nephelometers, electrodes, electromagnets, and/or LOCI® readers for interpreting the results of reactions within the reaction vessels or cuvettes. It should be understood that each of the steps described herein can be performed directly by or in response to programming instructions executed on one or more processor(s), such as computer <NUM>, available to analyzer <NUM>. These software instructions can be stored for execution via any conventional means including a hard drive, solid state memory, optical disk, flash memory, or the like.

As seen in <FIG>, a bi-directional incoming and outgoing sample fluid tube transport system <NUM> comprises a mechanism for transporting sample fluid tube racks <NUM> containing open sample fluid containers such as sample fluid tubes <NUM> from a rack input load position at a first end of the input lane <NUM> to the second end of input lane <NUM> as indicated by open arrow 35A. Liquid specimens contained in sample tubes <NUM> are identified by reading bar coded indicia placed thereon using a conventional bar code reader to determine, among other items, a patient's identity, tests to be performed, if a sample aliquot is to be retained within analyzer <NUM>, and, if so, for what period of time. It is also common practice to place bar coded indicia on sample tube racks <NUM> and employ a large number of bar code readers installed throughout analyzer <NUM> to ascertain, control, and track the location of sample tubes <NUM> and sample tube racks <NUM>.

A liquid sampling probe <NUM> is located proximate the second end of the input lane <NUM> and is operable to aspirate aliquot portions of sample fluid from sample fluid tubes <NUM> and to dispense an aliquot portion of the sample fluid into one or more of a plurality of vessels in aliquot vessel array <NUM>. This provides a quantity of sample fluid to facilitate assays and to provide for a sample fluid aliquot to be retained by analyzer <NUM> within an environmental chamber <NUM>. After sample fluid is aspirated from all sample fluid tubes <NUM> on a rack <NUM> and dispensed into aliquot vessels in array <NUM> and maintained in an aliquot vessel array storage and transport system <NUM>, rack <NUM> may be moved, as indicated by open arrow 36A, to a front area of analyzer <NUM> accessible to an operator so that racks <NUM> may be unloaded from analyzer <NUM>.

Sample aspiration probe <NUM> is controlled by computer <NUM> and is adapted to aspirate a controlled amount of sample from individual aliquot vessels in array <NUM> positioned at a sampling location within a track (not shown) and is then shuttled to a dispensing location where an appropriate amount of aspirated sample is dispensed into one or more cuvettes <NUM> for testing by analyzer <NUM> for one or more analytes. After sample has been dispensed into reaction cuvettes <NUM>, conventional transfer means move aliquot vessel arrays <NUM>, as required, within aliquot vessel array storage and dispensing module <NUM> between aliquot vessel array transport system <NUM>, environmental chamber <NUM>, and a disposal area (not shown).

Temperature-controlled storage areas or servers <NUM>, <NUM>, and <NUM>, contain an inventory of multi-compartment elongate reagent cartridges <NUM> loaded into the system via input tray <NUM>, such as those described in <CIT>, containing reagents in wells <NUM> perform a number of different assays. Computer <NUM> can control and track the motion and placement of the reagent cartridges <NUM>. Reagents from servers <NUM>, <NUM>, and <NUM> can be handled by one or more reagent probe arms, <NUM>, <NUM>, and <NUM>.

The liquid sampling probe <NUM> of the automatic chemical analyzer <NUM> is one example of a sampling probe which may be used to approach and collect a liquid sample. In these and other similar pipette apparatuses, proximity sensing is used in order to detect a relative location of the sampling probe with respect to the sample. For example, proximity sensing may be used to determine when a disposable tip has reached a surface of a sample such that a probe plunger can be activated to collect a predetermined amount of the sample. In order to perform proximity sensing, a sample probe system may include an air pump for liquid level sensing. Air flow is blown from the air pump through a sample probe manifold to a pressure transducer and finally to a disposable tip which can purge pumped air flow into the liquid. The system is able to sense that it has approached a new medium when it detects a rapid change in pressure reading due to the change of dynamic pressure to hydrostatic pressure (e.g., the flow of has been interrupted by the sample or other material).

<FIG> is a schematic diagram of a conventional sample probe system <NUM>. The sample probe system <NUM> includes a sample probe assembly <NUM> and an air supply assembly <NUM>. The air supply assembly <NUM> supplies an air flow to the sample probe assembly <NUM>. As the sample probe assembly <NUM> approaches a sample, the air flow is interrupted and a contact point or distance to the sample can be determined.

The sample probe assembly <NUM> includes, for example, a sample pump <NUM>, a transducer <NUM>, and a sample probe <NUM>. The sample pump <NUM> is a pump or valve which controls the receipt and delivery of a sample into the sample probe <NUM>. For example, the sample pump <NUM> may control a sample plunger which draws a liquid sample into a tip of the sample probe <NUM> through a linear plunger movement and expels the liquid sample through a reverse action. The transducer <NUM> is connected to a detection system (not shown) and configured to supply a signal based on a change in the air flow at the sample probe <NUM>. The term transducer is generally used in this case to describe any sensor (e.g., pressure sensor) which is configured to detect a change in the air flow from the sample probe <NUM>.

The air supply assembly <NUM> includes, for example, an air pump <NUM>, a filter <NUM>, and a pulse dampener manifold <NUM>. The air pump <NUM> is a mechanism configured to produce an air flow. The air pump <NUM> may include, for example, a rotary vane pump having a rotating blade and one or more valves which control the flow out of the air pump <NUM>. The air flow exits the air pump <NUM> and flows through the filter <NUM> which helps prepare the air flow and remove unwanted particles. As shown in <FIG>, the air flow exiting the air pump <NUM> and the filter <NUM> is a pulsating flow. This may be caused, for example, by the nature of a rotating blade to produce an uneven flow which pulsates along with the rotation of each vane. Moreover, the use of one or more valves interrupts the flow at certain times and inhibits a smooth flow.

The pulse dampener manifold <NUM> is present in the air supply assembly <NUM> in order to reduce the effect of the pulsating flow which exits the air pump <NUM> and filter <NUM>. The pulse dampener manifold <NUM> may be, for example, a long tube or conduit which allows the air flow to become more smooth and reduces the pressure oscillations as the air flows further downstream. If the pulsating flow were allowed to reach the sample probe assembly <NUM>, the transducer <NUM> may obtain incorrect readings and the detection system may not reliably detect the location of the sample probe <NUM> with respect to a sample. The pulse dampener manifold <NUM> may include one or more valves and one or more vents which remove the pressure pulsations from the flow and create a smooth laminar flow for the sample probe assembly <NUM>.

Embodiments of the present disclosure include a piezoelectric pump which produces pulsation-free flow and thereby eliminates the need for a pulse dampener or similar element. The piezoelectric pump can supply constant pressure flow and feed it directly into the sample probe assembly. This simplifies the sample probe system and reduces costs. Because the piezoelectric pump is able to operate at variable voltages, a logic control loop may be incorporated within the system software in order to tune the piezoelectric pump's operation and remove any biases caused by manufacturing, altitude, or other factor.

<FIG> is a schematic diagram of an exemplary sample probe system <NUM>, according to disclosed embodiments of the present invention. The sample probe system <NUM> includes a sample probe assembly <NUM>, an air supply assembly <NUM>, and a control system <NUM>. The sample probe assembly <NUM> includes a sample pump <NUM>, a transducer <NUM>, and a sample probe <NUM>. The sample probe <NUM> may include, for example, a disposable tip and a probe plunger configured to collect a sample in a manner known in the art. The sample pump <NUM> controls the probe plunger in order to draw in and/or expel a sample liquid into and out of the sample probe <NUM>. The air supply assembly <NUM> provides a pulsation-free air flow to the sample probe assembly <NUM> such that the transducer <NUM> can reliably provide signals to the control system <NUM> regarding sensing of the relative location of the sample probe <NUM> (e.g., the sample probe <NUM> contacting a sample). The transducer <NUM> may be any sensing device (e.g., a pressure sensor) which is configured to detect a change in the flow at the tip of the sample probe <NUM>. For example, the transducer <NUM> may detect a static pressure spike at the sample probe <NUM>. The static pressure spike indicates that the sample probe <NUM> is approaching a surface (e.g., a liquid surface of a sample). The transducer <NUM> provides signals to the control system <NUM>. The control system <NUM> is configured to analyze the signals to determine the positioning of the sample probe <NUM> with respect to a liquid sample, for example.

In some embodiments, the air supply assembly <NUM> includes a filter <NUM>, a piezoelectric pump <NUM>, and a pump valve <NUM>. The piezoelectric pump <NUM> is configured to supply constant pressure air flow to the pump valve <NUM>. The filter <NUM> is positioned in the air supply assembly <NUM> in order to clean the air flow prior to it being supplied to the sample probe assembly <NUM> (e.g., remove air particulate). The pump valve <NUM> is configured to selectively permit the flow of air to reach the sample probe assembly <NUM>. For example, the pump valve <NUM> is configured to stop the air flow to the sample probe assembly <NUM> when the sample pump <NUM> is drawing, carrying, and/or expelling a liquid sample. The pump valve <NUM> may additionally or alternatively include a bleed valve <NUM> configured to allow pressure to bleed from the system. The piezoelectric pump <NUM> is a bladeless pump which relies on the ability of piezoelectric materials to produce shape and configuration changes in a solid material through the application of an electrical voltage across to the material. The piezoelectric pump <NUM> may or may not include an internal valve. Instead, the piezoelectric pump <NUM> is aerodynamically designed to be more efficient during air expulsion and more resistive during suction.

<FIG> include schematic illustrations of exemplary embodiments of the sample probe system <NUM>. <FIG> illustrates a sample probe system 200A which includes a piezoelectric pump 226A, a pump valve 228A, a sample pump 218A, a transducer 220A, and a sample probe 222A. The sample probe 222A is comprised of a disposable tip and a sample probe plunger. In this embodiment, the sample probe system 200A omits a bleed valve and filter.

<FIG> illustrates a sample probe system 200B which includes a piezoelectric pump 226B, an air filter 224B, a pump valve 228B, a sample pump 218B, a transducer 220B, and a sample probe 222B. This embodiment includes the air filter 224B that removes unwanted particles from the air flow. The air filter 224B is positioned downstream from the piezoelectric pump 226B in this embodiment.

<FIG> illustrates a sample probe system 200C which includes an air filter 224C, a piezoelectric pump 226C, a bleed valve 229C, a pump valve 228C, a sample pump 218C, a transducer 220C, and a sample probe 222C. This embodiment includes both the air filter 224C and the bleed valve 229C. In this embodiment, the air filter 224C is positioned upstream from the piezoelectric pump 226C. This configuration may help to provide a more compact configuration by filtering the air on an inlet side of the piezoelectric pump 226C. The positioning of the air filter 224C also allows for the air filter 224C to be more easily changed. In this embodiment, the air filter 224C, piezoelectric pump 226C, bleed valve 229C, and pump valve 228C may be combined in a single, compact manifold. The use of the additional bleed valve 229C adds an additional component, but lowers risk of a leak or damage by allowing internal pressure to be more precisely controlled.

In each of the sample probe systems 200A, 200B, 200C, the low number of components reduces cost over conventional air pumps and provide a simple and efficient means to produce a smooth laminar flow which may be provided directly to a sample probe assembly. The air filter can be arranged either downstream or upstream from the piezoelectric pump or omitted altogether. A bleed valve may be included, but is not a necessary component. The various configurations may be tailored to the specific application of the sample probe system.

Returning to <FIG>, the control system <NUM> is electronically connected to the transducer <NUM> and is configured to receive signals from the transducer <NUM> which are indicative of a change in the air flow from the sample probe <NUM> (e.g., a change in static pressure). In this manner, the control system <NUM> is configured to detect the location of the sample probe <NUM> with respect to a sample. For example, the control system <NUM> may be calibrated to a baseline or threshold flow rate or pressure value and detect deviations which are indicative of a location of the sample probe <NUM> with respect to a surface of a liquid sample.

In some embodiments, the control system <NUM> is also configured to apply a voltage to the piezoelectric pump <NUM>. For example, the control system <NUM> may apply a voltage waveform to the piezoelectric pump <NUM>, thereby powering the pump and producing the air flow. The voltage waveform may be periodic (e.g., sinusoidal with a consistent amplitude variation and frequency) or aperiodic (e.g., inconsistent amplitude and frequency). The control system <NUM> may be configured to vary the voltage waveform to control the air flow produced by the piezoelectric pump <NUM> (e.g., increase or decrease the flow rate). For example, the control system <NUM> may also include a feedback control <NUM> which connects to the piezoelectric pump <NUM>. The feedback control <NUM> is incorporated into the control system <NUM> as a software control which tunes the operation of the piezoelectric pump <NUM> by varying the voltage waveform applied to the piezoelectric pump <NUM>.

<FIG> is a cross-sectional view of an exemplary embodiment of the piezoelectric pump <NUM>. The piezoelectric pump <NUM> includes an outer housing <NUM> and an inner pump <NUM>. The outer housing <NUM> includes an inlet side <NUM> and an outlet side <NUM>. The outer housing <NUM> defines an inlet opening <NUM> at the inlet side <NUM>, an outlet nozzle <NUM> at the outlet side <NUM>, and an intake channel <NUM>. The intake channel <NUM> connects the inlet opening <NUM> to the outlet nozzle <NUM>. The inlet opening <NUM> supplies air to the intake channel <NUM> and the inner pump <NUM> acts to expel the air out of the outlet nozzle <NUM>. The inlet opening <NUM> may be sized and configured to provide a smooth flow to the intake channel <NUM>. For example, the inlet opening <NUM> may include tapered edges which help to inhibit turbulence.

The inner pump <NUM> is positioned within the outer housing <NUM> and includes a plurality of walls <NUM> that define an air chamber <NUM>. The plurality of walls <NUM> include a diaphragm wall <NUM> which is formed of a flexible material and which preferably forms a boundary of the air chamber <NUM> on the inlet side <NUM> of the outer housing <NUM>, opposite the outlet nozzle <NUM>. The plurality of walls <NUM> further include an aperture <NUM>, which connects the intake channel <NUM> to the air chamber <NUM>. The aperture <NUM> is preferably positioned on the outlet side <NUM> of the outer housing <NUM>, opposite the inlet opening <NUM> and between the diaphragm wall <NUM> and the outlet nozzle <NUM>. The inner pump <NUM> further includes a piezoelectric element <NUM>. The piezoelectric element <NUM> may be attached to the diaphragm wall <NUM>. In some embodiments, the piezoelectric element <NUM> may form the diaphragm wall <NUM>.

The piezoelectric element <NUM> may be any piezoelectric material that is configured to expand and contract based on an input voltage supplied through an electrical connection. For example, the piezoelectric element <NUM> may contract when a predetermined voltage is applied and expand back to an original size when the predetermined voltage is removed. The diaphragm wall <NUM> is configured to flex as a result of the piezoelectric element <NUM> expanding and contracting. In particular, due to the diaphragm wall <NUM> being attached to the piezoelectric element <NUM>, a contraction of the piezoelectric element <NUM> may cause the diaphragm wall <NUM> to flex in order to move with the contracting piezoelectric element <NUM>. When the piezoelectric element <NUM> expands, the diaphragm wall <NUM> returns to its rest position. The movement and/or flexing of the diaphragm wall <NUM> with the contraction and expansion of the piezoelectric element causes the air chamber <NUM> to change in volume. For example, a volume of the air chamber <NUM> may be greater when the piezoelectric element <NUM> is in a contracted position and smaller when the piezoelectric element <NUM> is in an expanded position. The repeated movement of the diaphragm wall <NUM> thus produces a pumping action which draws air from the intake channel <NUM> through the aperture <NUM> into the air chamber <NUM> upon contraction of the piezoelectric element <NUM> and expels the air out of the air chamber <NUM> and ultimately out of the outlet nozzle <NUM> upon expansion of the piezoelectric element <NUM>.

The electrical connection is configured to provide a periodic electrical voltage to the piezoelectric element <NUM> in order to induce a repeated movement of the diaphragm wall <NUM> and thus a pumping action which produces a constant stream of air through the outlet nozzle <NUM>. According to a disclosed embodiment, the piezoelectric element <NUM> is an ultrasonic pump which receives the input voltage from the electrical connection at a frequency greater than <NUM>. The ultrasonic pumping action causes the ejected flow through the outlet nozzle <NUM> to be composed of small volume, high frequency micro pulses that result in pulsation-free flow.

As shown in <FIG>, the piezoelectric pump <NUM> may be formed as a rectangular element having a rectangular cross-section of the outer housing <NUM>. The plurality of walls <NUM> forming the inner pump <NUM> may also be formed such that the air chamber <NUM> is also rectangular. In one embodiment, the outer housing <NUM> has square dimensions of <NUM> x <NUM> and a height of <NUM>-<NUM> (e.g., <NUM>).

The intake channel <NUM> surrounds the inner pump <NUM> and delivers air to the aperture <NUM> from the inlet opening <NUM>. The inlet opening <NUM> is preferably larger than the outlet nozzle <NUM> such that the intake channel <NUM> is more easily supplied with air through the inlet opening <NUM>, thereby resisting intake flow backward through the outlet nozzle <NUM>. In this way, a steady-state flow is generated in which air is pushed outward through the outlet nozzle <NUM> by air which is expelled from the air chamber <NUM> without drawing air back into the intake channel <NUM> and the piezoelectric pump <NUM> is formed without valves.

In operation, the control system <NUM> of the sample probe system <NUM> controls an arm or other robotic element to move the sample probe assembly <NUM> into position to collect a sample. For example, the control system <NUM> may be an element of the analyzer <NUM> (e.g., computer <NUM>) and the sample probe assembly <NUM> corresponds to the liquid sampling probe <NUM> which is controlled through an automated movable arm. It should be understood, however, that other pipette apparatuses and immunoassay systems may incorporate one or more features disclosed.

The control system <NUM> is configured to apply voltage waveform to the piezoelectric element <NUM> via the electrical connection <NUM>. The applied voltage is preferably between <NUM>-<NUM> V, but is not limited thereto. During testing, these voltages produced air flows with sufficient pressure and desirable flow rates at the sample probe <NUM>. The applied voltage may be sufficient to produce ultrasonic oscillation of the diaphragm wall <NUM>. For example, the voltage may be applied at a frequency of approximately <NUM>-<NUM>. It should be understood, however, that the voltage waveform is not necessarily periodic. In some examples, an aperiodic voltage waveform may be applied.

The voltage waveform applied to the piezoelectric element <NUM> induces a pumping action which expels a constant, laminar air flow through the outlet nozzle <NUM>. The ultrasonic oscillation induced in the diaphragm wall <NUM> produces micro-pulses within the outlet flow which are negligible and dissipate at the outlet nozzle <NUM> to produce pulsation-free air flow out of the outlet nozzle <NUM>. The pulsation-free air flow reduces variation and allows the transducer <NUM> to reliably produce signals which are indicative of the relative location of the sample probe <NUM>. The control system <NUM> communicates with the transducer <NUM> and performs an analysis through software to identify the location of the sample probe <NUM> and perform one or more actions, accordingly. For example, the control system <NUM> may cause a probe plunger to be activated by the sample pump <NUM> to draw a sample through a tip of the sample probe <NUM>.

In some embodiments, the control system <NUM> further adjusts the voltage waveform based on the signals from the transducer <NUM> in order to tune the piezoelectric pump <NUM>. For example, the transducer <NUM> may produce signals which are indicative of pressure oscillations at the sample probe <NUM> and the control system <NUM> may adjust the applied voltage waveform in order to reduce the pressure oscillations and better produce a smooth, laminar flow. In another example, the control system <NUM> may adjust the voltage waveform to compensate for detected deviations from a baseline. For example, the control system <NUM> may compare a flow rate or pressure of an air flow at the sample probe <NUM> to a threshold and adjust the input voltage to the piezoelectric pump <NUM>. In this way, the control system <NUM> is configured to compensate for deviations caused by manufacturing biases, altitude, etc. In some embodiments, the control system <NUM> may alert a user when a deviation or unexpected value is detected at the sample probe <NUM>. For example, the control system <NUM> may determine that a filter change is needed and alert a user.

The disclosed sample probe system incorporates a piezoelectric pump which produces a pulsation-free flow without the need for a pulsation dampening manifold or other device which reduces pulsation at the cost of additional components and space. As a result, the air supply assembly of the sample probe system is simplified with less components and may also occupy less space than conventional pumps, thereby promoting cost and space efficiency. The electronic control of the piezoelectric pump also allows for a feedback control which allows the sample probe system to overcome various conditions, including manufacturing biases and altitude, and to detect conditions such as a dirty filter.

The embodiments of the present disclosure may be implemented with any combination of hardware and software. In addition, the embodiments of the present disclosure may be included in an article of manufacture (e.g., one or more computer program products) having, for example, computer-readable, non-transitory media. The media has embodied therein, for instance, computer readable program code for providing and facilitating the mechanisms of the embodiments of the present disclosure. The article of manufacture can be included as part of a computer system or sold separately.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope being indicated by the following claims.

An executable software application, as used herein, comprises code or machine readable instructions for conditioning the processor to implement predetermined functions, such as those of an operating system, a context data acquisition system or other information processing system, for example, in response to user command or input. An executable procedure is a segment of code or machine readable instruction, sub-routine, or other distinct section of code or portion of an executable application for performing one or more particular processes. These processes may include receiving input data and/or parameters, performing operations on received input data and/or performing functions in response to received input parameters, and providing resulting output data and/or parameters.

The functions and process steps herein may be performed automatically or wholly or partially in response to user command. An activity (including a step) performed automatically is performed in response to one or more executable instructions or device operation without user direct initiation of the activity.

Claim 1:
A sample probe system (<NUM>), comprising:
a sample probe assembly (<NUM>) comprising a transducer (<NUM>) and a sample probe (<NUM>);
an air supply assembly (<NUM>) comprising a piezoelectric pump (<NUM>) configured to supply an air flow to the sample probe assembly such that an air flow exits the sample probe (<NUM>);
wherein the transducer (<NUM>) is configured to detect a pressure change in the air flow and to provide signals to a control system (<NUM>) of the sample probe system which is configured to determine a relative location of the sample probe (<NUM>) with respect to a sample based on pressure changes in the air flow detected by the transducer (<NUM>),
characterized in that
the piezoelectric pump (<NUM>) is an ultrasonic pump which receives an input voltage at a frequency greater than <NUM>.