Patent Application
20120024085
The subject invention relates to sample vials and caps therefore typically including a septum used in automated sample handling equipment in the chemical analysis and life science industries.
In the chemical analysis and life science industries, sample vials are used, sealed with a cap including a septum. A syringe, piercing the septum, can be used to remove a portion of the sample in the vial or to add fluid to the vial. See U.S. Pat. No. 5,707,589 incorporated herein by this reference.
Automated sample handling equipment is now becoming more and more popular. Typically, such equipment includes robotic handlers which move trays of sample vials and/or pick and place handlers which grasp and move individual vials.
In some new equipment, magnetic handlers are used. “LEAP PAL” sample handlers and “CTC Analytics” handler are examples. Since the sample vials and caps currently available on the market were made of plastic or glass, manufacturers have begun to add a metal layer over or within the vial cap so that the vial can be retrieved and handled by the new magnetic handlers. Certain plastic caps, specifically thermoset plastics, for example phenolic, are also known to be brittle and consequently break or develop cracks under normal use conditions and assembly with the metal layer.
The expense and labor associated with such techniques, however, are unfavorable.
The subject invention features, in one example, a new plastic vial cap which can be made in a less expensive and less labor intensive manner. In one preferred embodiment, the vial cap includes a thermoplastic component containing sufficient material to impart effective attraction to the magnetic head of a handler used in new automatic sampling handling equipment.
The subject invention features a sample vial cap comprising a top portion made of plastic material and including an aperture, a septum about the aperture, a wall depending downward from the top, and a ferromagnetic substance included in the plastic material of the top portion. In this way, the vial cap is attracted to the magnetic head of a handler.
In one example, the cap wall also includes plastic material with a ferromagnetic substance therein. Typically, the top portion and wall are molded using a plastic material including a ferromagnetic substance therein. In one version, the ferromagnetic substance includes powders or flakes of metal such as stainless steel, iron, and/or magnetic iron oxide. The wall may include threads.
In one design, the sample vial cap comprises a top portion made of plastic material and including an aperture, a septum about the aperture, a plastic wall depending downward from the top portion, and metal powders or flakes included in the plastic material of the top portion and the wall.
The subject invention also features a method of making a sample vial cap. One preferred method includes mixing a ferromagnetic substance with a plastic material, adding the mixture into a mold configured to produce a sample vial cap with an opening for a septum, molding the cap, and adding a septum about the opening.
An automated sample handling apparatus in accordance with the subject invention includes a handler with a magnetic head used to retrieve and deposit sample vials sealed with caps each having a septum. Each said cap includes a ferromagnetic substance therein for attraction to the magnetic head. Typically, the cap is made of a molded plastic material with metal powders or flakes mixed therein.
The subject invention also features a sample vial cap which includes a plastic component and a ferromagnetic substance which is added to the plastic component. The plastic component may include a top portion with an opening sealed by a septum, an insert between a top portion with an opening and a septum disk sealing the opening, or a solid top portion with a wall depending downward therefrom.
The subject invention also features a sample vial crimp cap including a top portion with an opening, a plastic insert with a ferromagnetic substance therein, and a septum disk behind the plastic insert.
The subject invention also features a method of automatically handling samples. Plastic caps are formed for vials to include a ferromagnetic substance mixed therein. A sample is placed in a vial and the vial is sealed with the formed plastic cap. A handler with a magnetic head is employed to move the vial via magnetic attraction between the magnetic head and the vial cap.
In one method, forming may include adding an effective magnetic attraction composition of between 60-85% by weight of the ferromagnetic substance to 15-40% by weight of a polymer composition. Approximately 70% iron powder may be added to approximately 30% by weight of a polymer composition. The polymer composition may include a homopolymer and a copolymer polypropylene.
A thermoplastic polymer containing a filler in an effective magnetic attraction amount is formed into a vial cap. The subject invention, however, in other embodiments, need not achieve all these objectives and the claims hereof should not be limited to structures or methods capable of achieving these objectives.
Other objects, features and advantages will occur to those skilled in the art from the following description of a preferred embodiment and the accompanying drawings, in which:
Aside from the preferred embodiment or embodiments disclosed below, this invention is capable of other embodiments and of being practiced or being carried out in various ways. Thus, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. If only one embodiment is described herein, the claims hereof are not to be limited to that embodiment. Moreover, the claims hereof are not to be read restrictively unless there is clear and convincing evidence manifesting a certain exclusion, restriction, or disclaimer.
The Background Section above describes how new automated sample handling equipment includes magnetic heads used to transport vials sealed with a septum type cap. Accordingly, those skilled in the art have added, to standard plastic cap 10,
In accordance with the subject invention, cap 30,
As shown in
In one example, 60-85% metal by weight was added to the plastic material. In one specific example, 70% by weight Ancor 1000, iron power (Hoeganaes Co.) was added to a blend of homopolymer (15% by weight) and copolymer polypropylene (15% by weight). Polymer stabilizers may be added as well, as is known in the art. The relative amounts of the various polymers may vary. Caps can also be produced from other thermoplastic resins (or polymer) which contain ferromagnetic material in an effective magnetic attraction amount. Non-exclusive examples of other thermoplastic resins suitable for the subject invention include: polymethyl pentene, polyacetal, polybutylene terephthlate, polyamide 6, polyamide 66, polyamide 6/12, polyphenylene sulfide, and polyvinylidene fluoride. Thus, Polyacetals, polyesters, polyamides, PPS and/or fluoropolymers may be used for the plastic material. A weight percent range of 60-85% metal powder in polypropylene corresponds to a specific gravity (or density) range of 1.91 to 3.59 grams per cubic centimeter. A specific gravity range from 1.25 to 6.5 grams per cubic centimeter is possible when other thermoplastic resins containing ferromagnetic material are used.
The resulting pellets are then melted, step 46 and the melt is molded step 47 to produce a cap after which a septum is added, step 48. Molding of the cap is advantageously effected the same as a cap made only of plastic.
The septum is then added, step 48 by gluing it in place, by pressing operations, over molding, or the like. In one example, the methods of U.S. Patent Nos. 6,234,335 and/or 5,647,939 (incorporated herein by this reference) are employed to secure the septum in place. Because the preferred cap includes polypropylene, such methods are possible. The mold may include means to form threads such as shown 38 in
In this way, the same mold used to make purely plastic sample container caps with septums can be used to make metallized plastic caps reducing the cost and labor associated with rendering a plastic cap ferromagnetic in accordance with the prior art.
But, in accordance with one example of the subject invention, the ferromagnetic material is added to insert 64′,
In other embodiments, there is no septum.
Thus, the subject invention is highly versatile: for any style cap with a plastic component (e.g., the cap itself or an insert in a metal cap), ferromagnetic material is added to the plastic component so it is attracted to the magnetic head of the newer handlers. This is in sharp contrast to the way those skilled in the art have modified existing caps to include a ferromagnetic insert.
Although specific features of the invention are shown in some drawings and not in others, this is for convenience only as each feature may be combined with any or all of the other features in accordance with the invention. The words “including”, “comprising”, “having”, and “with” as used herein are to be interpreted broadly and comprehensively and are not limited to any physical interconnection. Moreover, any embodiments disclosed in the subject application are not to be taken as the only possible embodiments.
In addition, any amendment presented during the prosecution of the patent application for this patent is not a disclaimer of any claim element presented in the application as filed: those skilled in the art cannot reasonably be expected to draft a claim that would literally encompass all possible equivalents, many equivalents will be unforeseeable at the time of the amendment and are beyond a fair interpretation of what is to be surrendered (if anything), the rationale underlying the amendment may bear no more than a tangential relation to many equivalents, and/or there are many other reasons the applicant can not be expected to describe certain insubstantial substitutes for any claim element amended.
Other embodiments will occur to those skilled in the art and are within the following claims.
