Sample tube

Abstract

A sample tube including a cylindrical part and a conical part is described. The cylindrical part can include, a first wall portion having a first wall portion thickness, a second wall portion having a second wall portion thickness, and a shoulder including a planar first surface and a conically beveled second surface disposed between the first wall portion and the second wall portion. The first wall portion can be disposed closer to the planar first surface than the conically beveled second surface. The conical part can be shaped as a frustrum of a cone having a conical part wall thickness. The frustrum can include a wider-end and a narrower-end. The wider-end of the frustrum can be in contact with the second wall portion of the cylindrical part. At least one of the first wall portion thickness and the second wall portion thickness can be greater than the conical part wall thickness.

Description

CROSS REFERENCE TO RELATED APPLICATION [0001] This application is a continuation of U.S. patent application Ser. No. 10 / 691,186, filed Oct. 22, 2003, which is a continuation application of U.S. patent application Ser. No. 09 / 481,552, filed Jan. 11, 2000, now U.S. Pat. No. 6,703,236 B2, which is a divisional of U.S. patent application Ser. No. 08 / 422,740, filed Apr. 14, 1995, now U.S. Pat. No. 6,015,534, which is a continuation of U.S. patent application Ser. No. 08 / 201,859, filed Mar. 8, 1994, abandoned, which is a divisional of U.S. patent application Ser. No. 07 / 871,264, filed Apr. 20, 1992, now U.S. Pat. No. 5,475,610, which is a continuation-in-part of U.S. patent application Ser. No. 07 / 620,606, filed Nov. 29, 1990, abandoned, and of U.S. patent application Ser. No. 07 / 670,545, filed Mar. 14, 1991, abandoned. These applications, including Microfiche Appendices C, D, and E, filed in U.S. patent application Ser. No. 07 / 620,606 and U.S. patent application Ser. No. 07 / 871,264 and M...

AI Technical Summary

Benefits of technology

"The invention is a system for controlling the temperature of samples during polymerase chain reaction (PCR) protocols. The system includes a sample block with individual sample tubes that fit snugly into the block. The sample tubes are thin-walled and designed to decrease the delay in heat transfer between the sample block and the reaction mixture. The system also includes a heated platen that prevents solvent loss from the reaction mixture and a three-zone heater that allows for precise temperature control at different stages of the PCR protocol. The system is designed to achieve uniform temperature control and minimize cross-contamination between samples. The teachings of the invention also include a novel method and apparatus for controlling the PCR instrument and a novel microtiter plate design for accommodating up to 96 samples."

Problems solved by technology

Since the number of cycles is fairly large, this additional time unnecessarily lengthens the total time needed to complete the amplification.

However, in these prior art instruments not all samples experienced exactly the same temperature cycle.

In these prior art PCR instruments, errors in sample temperature were generated by nonuniformity of temperature from place to place within the metal sample block, i.e., temperature gradients existed within the metal of the block thereby causing some samples to have different temperatures than other samples at particular times in the cycle.

Further, there were delays in transferring heat from the sample block to the sample, but the delays were not the same for all samples.

The problems of minimizing time delays for heat transfer to and from the sample liquid and minimizing temperature errors due to temperature gradients or nonuniformity in temperature at various points on the metal block become particularly acute when the size of the region containing samples becomes large.

This large area block creates multiple challenging engineering problems for the design of a PCR instrument which is capable of heating and cooling such a block very rapidly in a temperature range generally from 0 to 100° C. with very little tolerance for temperature variations between samples.

First, the large thermal mass of the block makes it difficult to move the block temperature up and down in the operating range with great rapidity.

Second, the need to attach the block to various external devices such as manifolds for supply and withdrawal of cooling liquid, block support attachment points, and associated other peripheral equipment creates the potential for temperature gradients to exist across the block which exceed tolerable limits.

There are also numerous other conflicts between the requirements in the design of a thermal cycling system for automated performance of the.

However, it is seemingly impossible to add or remove large amounts of heat rapidly in a metal block by these means without causing large differences in temperature from place to place in the block thereby forming temperature gradients which can result in nonuniformity of temperature among the samples.

This makes it increasingly difficult to cycle the temperature of the sample block rapidly while maintaining accurate temperature uniformity among all the samples.

It is difficult to join metal parts in a way that insures uniformly high thermal conductance everywhere across the joint.

Nonuniformities of thermal conductance will generate unwanted temperature gradients.

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