Pipette tip system, device and method of use

This disclosure is directed to exemplary embodiments of systems, methods, techniques, processes, products and product components that can facilitate users making improved absorbance or fluorescence measurements in the field of spectroscopy with reduced (minimal) sample waste, and increased throughput, particularly in the study of biological sciences. A method and device for photometric measurement of liquids. The method includes the steps of: The method includes the steps of: providing a pipette tip, the pipette tip being made of an optically clear body having an outer wall and an inner wall, the inner wall defining an inner space for receiving a liquid sample, the inner space providing a cross-sectional path length for light; positioning the pipette tip between a light source and a light collector; measuring light transmission through the liquid sample; adjusting the inner space of the pipette tip to change the cross-sectional length, and measuring light transmission through the liquid sample. This can be accomplished by moving the light source from a first position to at least a second position to provide a plurality of cross-sectional path lengths through the liquid sample or by moving the pipette tip from a first position to at least a second position to provide a plurality of cross-sectional path lengths through the liquid sample.

TECHNICAL FIELD

This disclosure is directed to exemplary embodiments of systems, methods, techniques, processes, products and product components that can facilitate users making improved absorbance or fluorescence measurements in the field of spectroscopy with reduced (minimal) sample waste, and increased throughput, particularly in the study of biological sciences, with an objective, among others, of providing a unique, efficient solution to accurate absorbance/fluorescence measurements of liquid samples, and a reduction in equipment maintenance requirements.

BACKGROUND OF THE INVENTION

This disclosure is directed to exemplary embodiments of systems, methods, techniques, processes, products and product components that can facilitate users making improved absorbance or fluorescence measurements in the field of spectroscopy with reduced (minimal) sample waste, and increased throughput, particularly in the study of biological sciences, with an objective, among others, of providing a unique, efficient solution to accurate absorbance/fluorescence measurements of liquid samples, and a reduction in equipment maintenance requirements.

DESCRIPTION OF THE RELATED ART

Conventionally, there are two principal methods, techniques or processes by which liquid samples are measured and analyzed. The first conventional method involves use of a cuvette. A cuvette is a small tube generally of circular or square cross section, sealed at one end, and formed of a plastic material, glass, or fused quartz (for implementations that can involve the use of ultra-violet (UV) light). Cuvettes are designed to hold samples for spectroscopic experiments and analyses. Cuvettes are formed to have cross-sectional lengths, often 10 mm across, to allow for easy calculations of levels of illumination and/or coefficients of absorption. Cuvettes are filled with liquid samples and light from a light source is shone through the liquid samples, the light from the light source often being specifically regulated through a series of intervening optics structures on a light supplying or incident side of the cuvette and correspondingly on a light collecting or recovery side of the cuvette. The involved optical elements can include, for example, integrating spheres, an intention of which is to normalize the light passed through the liquid sample from the light supplying components and recovered by light collecting components. The collected light, having passed through the liquid sample, is then passed generally to a spectrometer to evaluate absorption of the light by the liquid sample, i.e., intensity of the collected light at various wavelengths. Cuvettes are generally not considered to be disposable items and, therefore, must be thoroughly washed between sample measurements to avoid contaminating the sample measurements. Further, cuvettes, and the processing of liquid sample measurements using those cuvettes, tend to waste a significant amount of a liquid sample.

The second method involves the spectroscopic measuring of liquid samples via a process by which microliter volume liquid samples are held by surface tension between two structural (anvil) surfaces. The anvil surfaces are highly polished, and generally include embedded optical fibers with ends finished flush with the anvil surfaces. Generally, one of the anvils is fixed, and the other of the anvils is movable to precisely control a distance between the anvils over which the absorption of the light by the liquid sample can be measured. U.S. Pat. No. 7,397,036 to Robertson et al., issued Jul. 8, 2008, describes such an exemplary measurement apparatus and method. A liquid sample is deposited on a small pedestal. The deposited liquid sample is then engaged by the anvils and essentially stretched as a liquid column supported between the anvil surfaces by surface tension in the liquid sample. This method, which still requires contact of elements of the measuring device with the liquid sample, also requires specific cleaning of the device surfaces between sample measurements to avoid contaminating subsequent liquid samples leading to potentially erroneous measurements. This cleaning must be carefully undertaken to not affect the cleaned and polished nature of the anvils and embedded optical elements in a manner that can adversely affect liquid sample adherence retention, and/or the optical analysis.

SUMMARY OF THE INVENTION

As will be described in specific detail below, the disclosed embodiments are directed to a unique pipette tip product that can address certain of the shortfalls in the conventional systems described above according to one or more of the following functional objectives. The inventive subject matter is: a method for photometric measurement of liquids. The method includes the steps of: providing a pipette tip, the pipette tip being made of an optically clear body having an outer wall and an inner wall, the inner wall defining an inner space for receiving a liquid sample, the inner space providing a cross-sectional path length for light; positioning the pipette tip between a light source and a light collector; measuring light transmission through the liquid sample; adjusting the inner space of the pipette tip to change the cross-sectional path length for light, and measuring light transmission through the liquid sample. This can be accomplished by moving the light source from a first position to at least a second position to provide a plurality of cross-sectional path lengths through the liquid sample or by moving the pipette tip from a first position to at least a second position to provide a plurality of cross-sectional path lengths through the liquid sample.

The inventive subject matter further includes: a device for photometric measurement of liquids made of: an optically clear body having an outer wall and an inner wall, the inner wall defining an inner space for receiving a liquid sample; the inner space having a surface shape to provide a cross-sectional path for light, wherein a portion of the inner space is comprised of a plurality of optically clear tubes of differing inner diameter, each of the plurality of optically clear tubes providing a cross-sectional path of different lengths.

The inventive subject matter further includes a device for photometric measurement of liquids made of: an optically clear body having an outer wall and an inner wall, the inner wall defining an inner space for receiving a liquid sample; the inner space having a surface shape to provide a cross-sectional pathlength for light, wherein a portion of the inner space is made of a first inner surface and a second inner surface, wherein the first inner surface and the second inner surface are non-parallel with respect to each other to provide the cross-sectional path length for light.

The inventive subject matter further includes a device for photometric measurement of liquids. The device being made of: an optically clear body having an outer wall and an inner wall, the inner wall defining an inner space for receiving a liquid sample; the inner space having a reflective surface which reflects a wavelength of light to provide an effective path length in which the reflective surface is either the inner or the outer wall.

DETAILED DESCRIPTION OF INVENTION

Exemplary embodiments of the systems and methods according to this disclosure can provide a unique pipette tip product for implementing the quantifying of concentrations of solid components in solution in liquid samples. In embodiments, the solid components can include biological specimens such as, for example, proteins and nucleic acids, in the liquid samples. Exemplary embodiments can provide for a pipette having a tip, the pipette configured to aspirate a fluid sample and hold the fluid sample within the tip, a pipette tip being inserted into a measurement system, the measuring system preferably having features for locating, and positioning the pipette tip appropriately to support the analysis of the liquid sample. In embodiments, the pipette tip can have, or be arranged to have, a cross sectional length in a light traversing direction to facilitate a spectroscopic analysis of the liquid sample in the pipette tip across the cross-sectional length. A pipette tip has a generally tubular or truncated cone shape with inner and outer walls, and an inner space for receiving a liquid sample. A portion of the inner space can be shaped to change the optical properties of the pipette tip. The portion of the inner space that is modified is the shape or size of the inner walls. The optical area is the area through which light passes.

In embodiments, the pipette tip can be held by any part of the tip or pipette in the measurement system structure, appropriately positioned between the measurement mechanics of the structure. In embodiments, the pipette tip can be ejected from, or remain connected to, the pipette when the pipette tip is properly positioned between the measurement mechanics of the measurement system structure. In embodiments, the pipette tip can be an integrated part of a transfer, bulb, or other single piece liquid collecting apparatus.

Exemplary embodiments can provide a specifically-cooperating light source with optics included for generating and projecting light onto an incident side of the pipette tip, and through the liquid sample, for collection on a recovery side of the pipette tip by light collecting elements. In embodiments, the light source can comprise one or more of a deuterium flash, a xenon flash lamp, a light emitting diode (LED), or other appropriate like light source. The light source can generally supply generated light to one or more of a fiber optics cable, a light pipe, or other light carrying/conveying medium. Combinations of these features can be generally referred to throughout this disclosure as a light source. Exemplary embodiments can provide that the light emitted by the light source can be made to pass through the disclosed pipette tip containing the liquid sample, and to be collected by a light collector. The light collector can be made of one or more of a second fiber optics cable, light pipe, or other light carrying/conveying medium. In embodiments, one or both light source and the light collector a further includes certain optics adjustment components, including, but not limited to, one or more lenses, mirrors, windows, and/or filters between the light source and the pipette tip and/or between the pipette tip and the light collecting unit. In embodiments, the light source and the light collector can be made of multiple cooperating output ports and input ports, respectively. These multiple numbers of cooperating output ports and input ports can be generally arranged in a structure commonly referred to as a multiplexer. In embodiments, the light source and the light collector can be one or both movable by means of manual or automatic operation with respect to each other in order that the one or both light source and the light collector can be movable closer to, or farther away from, the disclosed pipette tip, which can or cannot be used for positioning the pipette tip and/or optics. In embodiments, the pipette tip and/or pipette can be movable by means of manual or automatic operation to align the measurement area with the light supplying/collecting units.

Exemplary embodiments can provide that the light collector passes collected light, having traversed through the liquid sample in the pipette tip, to a spectrometer or similar detector for light intensity/absorption measurements. Resulting measurements can be related, via, for example, a processing device, to one or more reference values that can be usable to calculate a concentration of the liquid sample according to known means and techniques. Exemplary embodiments can provide a capacity to recover the pipette tip with the liquid sample inside allowing for no cross contamination of liquid samples, realizing minimal (essentially no) sample loss due to measurement, and substantially obviating any requirement to clean sample measurement surfaces between sample measurements, i.e., significantly reducing time-consuming maintenance requirements between sample measurements.

Now referring toFIG. 1, an exemplary embodiment is provided of a measuring system100made of a base unit110within which a pipette tip130can be inserted with the objective of measuring light transmission in a repeatable manner. The base unit110provides a means to make the measurements using at least one light source140positioned to supply light to a liquid sample in the pipette tip130and at least one light collector150positioned to collect light from a liquid sample in the pipette tip130. The exemplary measuring system structure100can include, for example, a base unit110and a component unit120. The component unit120is configured to secure a pipette tip130. To secure in this context means that the component unit120can be removable or an integrated part of the pipette tip130.

The component unit120, if removable, can be specifically configured to secure the pipette tip130. The pipette tip130can be secured by any conventional means to the component unit120, if removable. The pipette tip130can be secured to component unit120, if removable, for example, by a snap fit, friction fit, or any other similar mechanical means of joining two parts together in a non-permanent manner. Alternatively, the component unit120can be permanently secured to the pipette tip130during the manufacturing process.

An outer profile125of the component unit120can be configured to physically interact with an inner profile115of an accommodating space in the base unit110. This physical interaction between the outer profile125of the component unit120and the inner profile115of the base unit110can provide controlled structural alignment of the pipette tip130between a light source140and a light collector150fixedly or movably mounted in the base unit110.

An advantage of the illustrated and described physical interaction between the outer profile125of the component unit120and the inner profile115of the base unit is that it provides an essentially self-aligning structure for repeatable positioning of the pipette tip130that substantially obviates a requirement, such as can be required in the conventional microliter volume drop method discussed above, for the user to be exceptionally precise in guiding the pipette tip130to a particular pedestal on which the sample volume drop can be deposited.

Another advantage of the exemplary physical embodiments according to this disclosure is that they further remove a requirement for ejecting the liquid sample material from the pipette tip, thereby further obviating the attendant requirement to clean surfaces within, for example, the accommodating space in the base unit110, or any of the associated structural components of the exemplary measuring system structure100, as depicted. In other words, the liquid sample need never touch any of the surfaces of the structure but can, in all instances, remain substantially within the pipette tip130.

Generally, the disclosed pipette tip130is a liquid collecting tip for a pipette that fits onto the pipette. In embodiments, the pipette tip130can be attached to, and/or removable from, the pipette. The attachment to the pipette tip130can be accomplished using standard methods including, for example, a snap or press fit to the pipette. More broadly, the pipette tip130can be held in place by means of physical pressure, magnetism, gravity, suction, or any similar method upon a surface of the pipette tip130or the pipette body itself. When removable/detachable from the pipette, the pipette tip130can be a disposable component. Otherwise, when removable/detachable from the pipette, the pipette tip130can be a cleanable and reusable component. The pipette tip130can be formed of any geometry to substantially prevent loss of the liquid sample if ejected from the pipette. The pipette tip130can be formed of an optically clear material. The pipette tip130can have applied to it appropriate light transmittance zones or features in one or multiple areas for light to pass through with minimal interruption.

FIG. 2illustrates an exemplary embodiment200for an exemplary pipette tip230according to this disclosure. As shown inFIG. 2, the pipette tip230is made of an outer wall205and an inner wall208. The inner wall208defines an inner space210for receiving a liquid sample. The inner space of the pipette tip can be adjusted to change the cross-sectional length and thus the optical properties. For example, the inner space210of the exemplary pipette tip230can be formed, or otherwise configured, to have a plurality of optically clear tubes of differing inner diameter, thus providing different cross-sectional path lengths. These stacked tube segments232,234and236can be made of quartz, sapphire, plastic, glass, ceramics, or any like material capable of passing the desired wavelength of light. The stacked tube segments232,234and236can be sized to accommodate a range of concentration levels. Larger diameters allow for lower concentration detection, and smaller diameters allow for higher concentration detection. Path length is defined by the ID of each of the stacked tube segments232,234and236. The stacked tube segments232,234and236can be made of a single machined piece or an assembly of multiple parts. Multiple part assembly can be connected by means of optical cement, chemically compatible adhesive, mechanical means (press fit, clamp, etc.), or any other method of coupling tubing. The optical area of the stacked tube segments232,234and236can be polished for increased clarity. The symmetry of the stacked tube segments232,234and236negates the necessity of pipette tip230orientation. Because of symmetry, the area of the tube that light enters, and exits is not dependent upon the rotational position of the tip about its central axis. The light will behave similarly when entering and exiting the tube independent of rotation of the tip. The tip can be aligned with the light supplying and collecting entities via a v-groove piece or similar method of gripping the OD of one or more of the tubes. In operation, light enters the sample contained in a stacked tube segment232,234and236via one or more light source240. In this embodiment, one or more light source240, can be stationary or movable. The light source240can move towards or away from the pipette tip230to make clearance for the pipette tip230to be inserted and grip the pipette tip230for orientation. The light source240can moved on a bearing surface (not shown) and can be actuated by a motor (not shown). The light is collected via one or more light collectors250after traveling through the liquid sample by means of optics not shown) if necessary for analysis. The light may need to be directed, after exiting the pipette tip230, with the help of optics (not shown) such as a ball lens into the light collecting entity for analysis. Light collectors250can be stationary or movable. The light collectors250can move towards or away from the pipette tip230to make clearance for the pipette tip240to be inserted and grip the pipette tip230for orientation.

Now referring toFIG. 3A, the pipette tip330is made of an outer wall305and an inner wall308. The inner wall308defines an inner space310for receiving a liquid sample. The inner space310of the exemplary pipette tip330can be formed, or otherwise configured with reflective surfaces that provide variable cross-sectional path lengths. For example, long cross-sectional path lengths allow low concentration detection limits.

The reflective surfaces320are created by the inherent nature of the material, a coating method (dipped, thin film deposition, etc.), and/or optical manipulation (total internal refraction, fiber Bragg grating, etc.) The pipette tip330can include flat, angled, curved, or complex geometry surfaces to manipulate the cross-sectional light path. The cross-sectional path length332through the liquid sample is determined by the trajectory of the supplied light. The effective cross-sectional path length332is the cumulative lengths of the reflected light. The light can be supplied at any angle from any direction by a light source340.

A section of the inner wall308and outer wall305form a window port360capable of passing a desired wavelength(s) of light in this embodiment. The port360can be an optical filter. Next light enters the pipette tip330through a window port360and is reflected any number of times through a liquid sample inside. Window ports360,370can be plastic, quartz, sapphire, or any material capable of passing the desired wavelength(s) of light. Window ports360and370are not required to have reflective properties. The light is collected after traveling through the liquid sample by a light collector350and optics (not shown) if necessary for analysis. Light exits the pipette tip330via a window port a window port370.

Now referring toFIG. 3B, the reflective surfaces320is for example a fiber Bragg grating. A fiber is manufactured to have a hollow core. The walls of the fiber contain a grating which reflects wavelengths of light. The fiber portion of the pipette tip may be drawn over a mandrel to create a cavity within the fiber or any other appropriate manufacturing technique. The cavity has the capacity to hold liquid or gas samples. A fiber Bragg grating is created during the manufacturing process for the reflection of one or more wavelengths of light. Light is supplied to the pipette tip300and reflects at the specified wavelengths. The light can be supplied at any angle from any direction by a light source340. The reflected light or passed light may be collected by a light collector350oriented parallel or perpendicular to the axis of the tip. The light source340may be the same entity as the light collector350in this instance depending upon the nature of the reflections. The light collected may be analyzed by means of a spectrometer or similar device (not shown).

Now referring toFIG. 4, an exemplary embodiment400for an exemplary pipette tip430according to this disclosure is illustrated with a variable light source. In this embodiment, the surfaces of the pipette tip430geometry are designed to accept light of varying positions and/or angles of origin. Outside and/or inside the pipette430tip can reflect or refract light to control cross-sectional path length by changing the angle or location of light entry into the pipette tip430. A circular cross section is shown inFIG. 4, although the cross section may be flat, angled, curved, or of complex geometry dictated by desired cross-sectional path length range, tip materials, and tip manufacturing methods. In this embodiment, a light source440is movable. Three positions,441,442, and443, of a single light source are shown inFIG. 4. The light source can be movable by for example an actuating motor and bearing sub-system (not shown). The cross-sectional path length432,434,435through a liquid sample changes depending upon the position,441,442, and443, of the light source. The light source is moved from a first position to at least a second position to provide a plurality of cross-sectional path lengths for light through the liquid sample. The pipette tip430geometry can include flat, angled, curved, or complex geometry surfaces to manipulate light cross-sectional path length432,434,435. The light is collected after traveling through the liquid sample by using optics460if necessary for analysis. The light can be directed, after exiting the pipette tip430, with the help of optics460such as a ball lens into the light collector450for analysis. The light collector450can be fixed or movable.

Now referring toFIG. 5an exemplary embodiment500for an exemplary pipette tip according to this disclosure is illustrated with a fixed light source. In this exemplary embodiment, a variable pipette tip position is shown.FIG. 5depicts the top view of a pipette tip with a circular cross section in three positions510,511, and512. The pipette tip is moved from a first position510to at least a second position511and or512to provide a plurality of cross-sectional path lengths through the liquid sample. The pipette tip's position is relative to the location to the light source540. A fixed light source540emits light that passes light through a liquid sample contained in a movable pipette tip.510,511, and512. The pipette tip can be moved by use of a motor for actuation, and bearings (not shown) to provide repeatability of position. The geometry of the pipette tip dictates cross-sectional path length of the light through the liquid sample as the pipette tip moves. The pipette tip includes flat, angled, or curved sections to create the desired path length. The pipette tip can be moved to position510,511, and512. The movement of the tip position changes the cross-sectional path length532,533,534. The light is collected via a light collector550after traveling through the liquid sample by means of optics560if necessary for analysis. The light collector550can be fixed or movable.

Now referring toFIG. 6, an exemplary embodiment600for an exemplary pipette tip630according to this disclosure is illustrated with a light source640that may be fixed or movable. The light source can be movable by for example an actuating motor and bearing sub-system (not shown). In this exemplary embodiment, non-parallel inner tip surfaces are provided. A light source640provides light to a liquid sample610contained in a pipette tip630. The distance between the inner surfaces621, and622of pipette tip630create a cross-sectional path length632of light through the sample610. The inner surfaces621, and622of the pipette tip630can be at any orientation relative to each other. The inner surfaces621, and622of the pipette tip630may be of a flat, curved, or of complex shape. The inner surfaces621, and622of the pipette tip630can be plastic, quartz, sapphire, or any material capable of passing the desired wavelength(s) of light. Light is collected via a light collector650after passing through the pipette tip630. Optics660may be utilized to guide the light to the light collector650.

Now referring toFIG. 7a system700that was created by connecting a fiber optics cable with quartz core710to a light source720on one end, and to one of the threaded fiber bushings650on the other end is illustrated. A second fiber optics cable730having a quartz core larger than710was connected to the remaining threaded fiber bushing650on one end, and to a spectrometer740on the other end. The spectrometer740fed into a personal computer750with software appropriate for graphical interpretation of the spectrometer's740signal to measure light intensity.

The cartridge500was placed approximately in the center between the two bearing blocks620with minimal support by a loose-fitting slot machined into base plate610. The bearing blocks620were moved along the linear bearings630to allow the lips660to meet the quartz discs520. This interaction aligned the fiber optics cables710and730perpendicular with the quartz discs520. Measurements of light intensity were taken from this configuration. Measurements were taken with air between the quartz discs520in cartridge500, and water for comparison. Between every measurement the cartridge500was removed from the base600and replaced to create non-repeating starting locations of the cartridge500for each measurement. The results of these measurements can be seen in TABLE 1.

The results in TABLE 1 correspond to respective linear regression lines with R-squared values greater than 0.9 each. A person familiar with this value will recognize there is a clear linear trend. Using personal computer750intensity values integrated over time would yield precise intensity measurements, which in turn produce precise absorbance/fluorescence measurements. Example 1 is analogous to inserting a pipette tip into a mechanism and relying on the mechanism to create the necessary perpendicularity.

Specific reference to, for example, the above-discussed embodiments for the disclosed pipette tip, and the characteristics thereof, should not be interpreted to constrain the disclosed pipette tip to only those embodiments. The depicted and described embodiments are included for non-limiting illustration of the disclosed products for implementing systems, methods, techniques, processes and schemes for liquid sample observation, measurement and analysis, which should, therefore, be interpreted and as being exemplary only, and not limiting the disclosed schemes, in any manner.

Features and advantages of the disclosed embodiments are set forth in this disclosure and can be, at least in part, obvious from this detailed description, or can be learned by practice of the disclosed embodiments. The features and advantages of the disclosed embodiments can be realized and obtained by means of the instruments and combinations of features particularly described.

Various embodiments of the disclosed systems and methods are discussed in this disclosure. While specific implementations are discussed, this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations can be used without departing from the spirit and scope of the disclosed embodiments.