Measuring and testing – Liquid analysis or analysis of the suspension of solids in a... – Sampler – constituent separation – sample handling – or sample...
Reexamination Certificate
2000-03-01
2001-11-20
Williams, Hezron (Department: 2856)
Measuring and testing
Liquid analysis or analysis of the suspension of solids in a...
Sampler, constituent separation, sample handling, or sample...
C073S863010, C422S128000
Reexamination Certificate
active
06318158
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates in general to sample analysis, such as, but not limited to systems for conducting particle size measurements, and is particularly directed to a new and improved sample preparation and delivery apparatus that is operative to controllably sonically mix, and deliver the contents of samples, such as particulates, stored in containers, that are transported by a controllably indexed conveyor to the input reservoir of an associated sample analysis system.
BACKGROUND OF THE INVENTION
Systems employed for particulate sample analysis, such as, but not limited to, those employed in medical and industrial applications to analyze particles in raw materials used to develop final products, customarily include, or are coupled with, some form of sample delivery and mixing apparatus, that ‘prepares’ a respective sample, namely, places it in the physical condition necessary for acceptance and processing through the analyzer. Typically, preparation of a particulate sample involves suspending and separating the particles in a prescribed fluid carrier (such as an aqueous solution), which is then injected into a fluid transport channel for delivery to a particle measurement (e.g., optical illumination-based) subsystem.
For this purpose, as diagrammatically illustrated in
FIG. 1
, the front end of a sample analyzer
13
, having an associated computer workstation
11
, includes an input reservoir
12
to which a respective sample
15
is dispensed (for example by way of a sample-retaining test cup, tube or the like
16
to the reservoir by way of a conveyor
17
). In order to place the sample particles in a solution for analysis, the reservoir is supplied from a carrier fluid source
21
with a carrier fluid into which the sample is to be mixed, and from a surfactant source
23
with a surfactant that serves to disperse the particles of the sample
15
within the carrier.
A sonic probe (or sonicator)
31
is inserted into the reservoir
12
and which is then stimulated by an ultrasonic drive signal from an energization source
33
, so as to cause a sonically induced agitation of the combination of carrier fluid, sample and surfactant. This sonic mixing operation is intended to thoroughly separate and suspend the sample particles in the carrier fluid, so that the mixed contents of the reservoir are in the appropriate physical state required by the sample analyzer
13
. Once the analysis has been completed, the reservoir and fluid flow path through the analyzer are subjected to a purging rinse, in preparation for the next sample.
Unfortunately, there are a number of problems associated with such a conventional sample-preparation configuration. One of the most significant is the fact that the sonicator is actually immersed into the fluid contents of the reservoir. Because the volume of the reservoir is relatively large, the sonic energy emitted by the probe is reduced as it diffuses into the contents of the reservoir. This means that a relatively large amount of probe drive energy is necessary to obtain thorough mixing of the sample in the carrier, resulting in poor efficiency of the sonicator operation.
In addition, because the probe is immersed into the mixture, it not only may displace some of the sample, but itself becomes coated with sample and surfactant, and therefore requires cleaning after each use. Moreover, depending upon the application, the mixture into which the probe is inserted may be corrosive to the probe, which shortens the life of the probe.
SUMMARY OF THE INVENTION
In accordance with the present invention, these and other shortcomings of conventional sample delivery and mixing devices are substantially reduced or effectively eliminated by a sample mixing and delivery apparatus, that is configured to thoroughly sonically prepare (mix) each sample, such as a sample containing one or more particulates, to be analyzed in its own storage container (e.g., test tube) prior to being dispensed into the analyzer reservoir, and without having to insert the sonicator probe into the sample.
For this purpose, a controllably indexed conveyor, such as a carousel, is operative to retain and transport a plurality of sample containers. The sample containers (such as test tubes) are made of a material, such as an elastically deformable transparent plastic, and the like, that is compliant to acoustic energy emitted by a sonicator probe tip placed directly against or in intimate contact with the exterior of the test tube wall. In a non-limiting, but preferred embodiment, the carousel includes a slotted disk that is controllably rotationally indexed by a releasable clutch.
The clutch may include a plurality of ball bearings sized to releasably engage depressions in the carousel disk. In the event of an impairment, the carousel disk will ride up over the ball bearings and slip on the clutch, thereby preventing damage, or injury to the user. The carousel disk also includes a mechanically encoded surface structure, configured to interface with a set of indexing sensors, which provide output signals to a supervisory system controller.
A radially translatable sonicator unit is supported beneath the carousel disk and includes a generally longitudinal probe element. A controllably mechanical bias arrangement is coupled to the sonicator unit and serves to urge or bias the sonicator unit in a radially outward direction toward or away from the center of the carousel and toward its cylindrical periphery. Outward biasing displacement of the sonicator brings the distal end of the probe into intimate contact with the lower portion of a sample-containing test tube, that has been indexed by the carousel disk to a ‘mixing’ location associated with a ‘filling’ station directly opposite the sonicator unit.
The apparatus optionally includes a ‘filling’ station containing a carrier fluid and surfactant supply unit, that is operative to controllably dispense a measured quantity of fluid and surfactant into a respective test tube, that has been rotationally indexed by the carousel to the filling station in preparation for sonication of the sample according to the prior art.
The filling station operates to dilute the sample with a carrier fluid sufficient for effective sonication, which disperses particles of the sample for analysis. As appreciated by one skilled in the art, if the sample is a solution, which contains liquid sufficient for effective sonication, carrier fluid will not need to be added to the sample solution. Moreover, the carrier fluid can comprise a surfactant solution, which facilitates the separation of particles in the sample. Preferably, the carrier solution dilutes the sample to form a sample solution, and a surfactant is added to the sample solution. After dispensing any carrier and/or surfactant by the supply unit, and with the sonicator probe biased into intimate contact with the lower portion of the test tube, the sonicator is energized.
Because the test tube is made of a material that is compliant to acoustic energy emitted by the sonicator unit, and with the sonicator probe tip being urged against a generally lower portion of the test tube where the sample contents tend to gravitate, the sonic energy emitted by the sonicator probe is efficiently transmitted through the sidewalls of the test tube, and effectively concentrated upon that volume of the test tube containing the particulate of the sample. This provides for maximum efficiency particle separation and rapid mixing of the sample, surfactant and carrier fluid.
This substantially improved efficiency of acoustic energy coupling of the external sonicator of the invention means that the amount of sonicator drive energy required to achieve through mixing of the sample can be significantly reduced, in comparison with the relatively poor efficiency of the immersed probe approach of the prior art, described above. Moreover, since the sonicator of the invention is not immersed into the sample, it does not displace any of the contents of the test tube, and cannot become coated or contaminated thereby.
Beaulieu Mark M.
Breen Thomas
Cuervo Arys S.
Rodriguez Enrique
Alter Mitchell E.
Coulter International Corp.
Cygan Michael
Wands Charles E.
Williams Hezron
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