A. Field of the Invention
This invention relates to systems and methods for moving a test sample or group of test samples to various stations of a machine, such as a biological sample testing machine.
B. Description of Related Art
Biological samples can be subject to chemical or optical analysis using various techniques, one of which is transmittance and/or fluorescence optical analysis. The purpose of the analysis may be to identify an unknown biological agent in the sample, test the sample to determine the concentration of a substance in the sample, or determine whether the biological agent is susceptible to certain antibiotics, as well as the concentration of antibiotics that would be effective in treating an infection caused by the agent.
A technique has been developed for conducting optical analysis of biological samples that involves the use of a sealed test sample card containing a plurality of small sample wells. Typically, during manufacture of the cards e.g. for microbiological analysis, the wells are filled with either various types of growth media for various biological agents, or else various concentrations of different antibiotics. The cards have an internal fluid passageway structure for allowing fluid to enter the wells of the card through a transfer tube port, and an integral transfer tube extending outwardly from the transfer tube port. The prior art method involved the manual insertion of one end of the transfer tube into the card and the other end into a test tube, and then the manual placement of the card with attached transfer tube and test tube into a vacuum filling and sealing machine, such as the Vitek.RTM. Filler Sealer. The filling and sealing machine generates a vacuum, causing the fluid in the test tube to be drawn into the wells of the sample card.
After the wells of the card are loaded with the sample, the cards are manually inserted into a slot in a sealer module in the machine, where the transfer tube is cut and melted, sealing the interior of the card. The cards are then manually removed from the filler/sealer module and loaded in a column fashion into a reading and incubating machine, such as the VITEK.RTM. Reader. The reading and incubating machine incubates the cards at an incubation temperature, and has an optical assembly that moves up and down relative to the cards to read the wells of the cards.
This arrangement has limitations, in that two machines are required to process and analyze the cards. Furthermore, additional time and labor are required to conduct the complete analysis of the card.
To combine the several functions of biological sample processing and optical reading into a single automatic sample processing and reading machine poses substantial challenges. One particularly difficult challenge is to provide a positioning system to move the samples about the machine from station to station. The present invention provides a positioning system that is reliable, precise in its positioning of the samples, and that is suitable for the varied types of operations performed on automated sample testing equipment such as test sample cards.
Representative prior art test sample positioning systems for use in biological and immunoassay analyzer machines are described in U.S. Pat. No. 4,265,855 to Mandle et al., U.S. Pat. No. 5,232,665 to Burkovich et al., U.S. Pat. No. 4,890,930 to Nohso, U.S. Pat. No. 4,710,352 to Slater et al., U.S. Pat. No. 4,632,808 to Yamamoto et al., and U.S. Pat. No. 4,236,825 to Gilford. These systems tend to either have unnecessary complexity in their mechanical components or involve drive and transport systems that are unsuitable to the processing of test sample cards and the associated test tubes. The system described in the above-cited Mandle et al. patent discloses a drive pin arrangement for moving a set of blocks carrying test tubes about an immunochemical analysis machine. The machine is fully loaded with blocks positioned in front and rear rows, with a vacant spot for one block at opposite corners of the machine. Drive pins then move simultaneously to push one block from the front row to the vacant spot on the back row, and one block from the back row to a vacant spot on the front row. The blocks are then advanced one space along the length of the front and rear rows, and the process repeats. The functioning of this drive system is dependent on the machine being filled with blocks, and hence lacks flexibility. Further, in order for one block to be moved through all the stations of the machine, the blocks in front of it must first be cycled through the stations around the machine.
The present invention overcomes the disadvantages of the prior art positioning systems by providing an efficient test sample positioning system for that is suitable for biological and chemical sample testing machines. It provides independent drive systems that can simultaneously transport a number of trays loaded with samples independently, permitting processing by the various stations of the trays at the same time, without the delays and complexities found in many prior art systems. The invention further permits the performance of the functions of loading sample fluids into the cards and reading of the cards in a single machine automatically and without human intervention, thus achieving a significant advance in the art. These and other objects, advantages and features of the invention will become more apparent from the following detailed description of a preferred embodiment of the invention.