Automatic analysis device

Abstract

The present invention adopts the following configuration to provide an automatic analysis device capable of avoiding occurrence of analysis failures due to shortage of a residual liquid.　This automatic analysis device includes: a probe for sucking a liquid in a container; and a capacitance measurement mechanism for measuring capacitance between the probe and the liquid stored in the container. The automatic analysis device includes a liquid amount calculation mechanism for calculating an amount of the liquid on the basis of a value of capacitance at a time when the probe is brought into contact with the liquid stored in the container, the value being measured by the capacitance measurement mechanism.

Description

automatic analyzer

[0001] The present invention relates to an automatic analyzer.

[0002] When a sample is tested for multiple different analysis items in an automated analyzer used in clinical testing, a dispensing probe is used to dispense the sample from a single sample container into multiple different reaction containers, the number of which corresponds to the number of analysis items. The sample containers are often test tube-shaped, with a hemispherical bottom. Therefore, after repeated sample aspiration, if the remaining sample volume falls below a certain level, the probe will no longer be able to aspirate the sample even if there is still sample remaining (the remaining sample volume at that point is called the dead volume). If the desired sample volume cannot be aspirated, the reaction will not proceed normally, potentially resulting in an unsuccessful analysis.

[0003] To avoid this problem, it is effective to aspirate the sample after it has been confirmed that there is a sample that can be aspirated in the sample container. Patent Document 1 discloses an automatic analyzer that determines the presence of liquid in a sample container by detecting when the tip of a probe contacts the liquid surface in the container using a capacitance method.

[0004] Japanese Patent Application Publication No. 10-282116

[0005] The technology described in Patent Document 1 can detect the presence of liquid in a container by detecting the liquid level. However, it cannot directly determine how much liquid remains in the container. In other words, the liquid level can only be calculated from the "relationship between the liquid level and the remaining amount of sample" calculated based on the shape of the sample container.

[0006] Accurately knowing the remaining amount of sample is especially important when the remaining amount is close to the dead volume. If the remaining amount is judged to be insufficient even though there is sample that can be analyzed, valuable sample will be wasted. On the other hand, if the remaining amount is judged to be sufficient but the actual amount of sample dispensed is insufficient, analysis will be faulty and reagent will be wasted.

[0007] An object of the present invention is to provide an automatic analyzer that can directly know the amount of liquid remaining in a container, thereby avoiding the occurrence of analytical failures due to insufficient remaining liquid.

[0008] The present invention provides an automated analyzer that solves the above-described problems, comprising: a probe that aspirates liquid from a container; and a capacitance measurement mechanism that measures the capacitance between the probe and the liquid contained in the container, the automated analyzer also comprising a liquid volume calculation mechanism that calculates the volume of the liquid based on the capacitance value measured by the capacitance measurement mechanism when the probe comes into contact with the liquid contained in the container.

[0009] According to the present invention, an automatic analyzer can be provided that can directly know the amount of liquid remaining in a container, thereby avoiding the occurrence of analysis failures due to insufficient remaining liquid.

[0010] A plan view showing the overall configuration of an automatic analyzer. A schematic diagram of the capacitance generated between a dispensing probe and an electrode facing the dispensing probe. A functional block diagram of an automatic analyzer. Changes in capacitance when the dispensing probe is lowered. The relationship between the average capacitance after contact with the liquid and the liquid volume when sample suction is repeated. A flowchart for determining the remaining sample volume from the capacitance.

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following description shows specific examples of the contents of the present invention, and the present invention is not limited to these descriptions. Various changes and modifications can be made by those skilled in the art within the scope of the technical ideas disclosed in this specification. Furthermore, in all drawings used to explain the present invention, parts having the same function are designated by the same reference numerals, and repeated explanations thereof may be omitted.

[0012] 1 shows an outline of an automated analyzer 100. A probe 203 can rotate in a horizontal plane and move up and down, and can aspirate a predetermined amount of specimen contained in a specimen container 102. After aspirating the specimen, the probe moves above an incubator (reaction disk) 104 and then descends to dispense the specimen into an unused reaction container 105 held in the incubator 104.

[0013] Furthermore, the probe 114 (reagent dispensing probe) is immersed in the reagent in the reagent container 118 housed in the reagent disk 111 and aspirates a predetermined amount of reagent. The probe 114 then rises and rotates, moving to a predetermined position above the incubator 104, and dispensing the reagent into the reaction container 105 into which the sample has been dispensed. This completes the general operation of the automated analyzer 100.

[0014] A typical capacitance-type liquid level detector installed in an automatic analyzer detects contact between the probe tip and the liquid surface from changes in capacitance between the probe and an electrode installed opposite the probe. When the probe tip is not in contact with the liquid surface, air above the liquid surface exists between it and the opposing electrode. The relative dielectric constant of air is smaller than that of liquid. Therefore, the capacitance is small when the liquid surface and the probe tip are not in contact. When the probe tip comes into contact with the liquid surface, there is no longer any air present, so the capacitance increases suddenly in a step-like manner. Based on this step-like change in capacitance, it is possible to detect that the probe tip has come into contact with the liquid surface. In this case, what is being looked at is the change in capacitance, not the value of the capacitance itself.

[0015] An example of an embodiment will now be described. In this example, the remaining amount of sample is determined in a cylindrical sample container with a hemispherical bottom, such as a test tube.

[0016] 2 is a diagram showing a typical liquid dispensing mechanism, which is a schematic diagram showing the capacitance between a probe 203 and an electrode (ground electrode) 205 arranged opposite the probe.

[0017] In the capacitance method, the capacitance between the probe tip 204 (which has a structure in which metal is exposed at the tip to function as an electrode) and the opposing electrode 205 changes rapidly before and after contact with the liquid, as described above, and this is used to detect when the probe tip has come into contact with the liquid.

[0018] Figure 4 is a graph showing the change in capacitance when the probe is lowered and the probe tip (capacitance detection unit) touches the liquid surface. It can be seen that the capacitance changes stepwise when the probe is lowered and the probe tip touches the liquid surface. Conventional techniques focused only on this stepwise change in order to detect the liquid level. In this invention, however, we focus on the capacitance value itself, particularly the value of the capacitance that becomes flat after the probe touches the liquid surface.

[0019] The capacitance after the capacitance detection unit comes into contact with the liquid depends on the amount of liquid remaining in the container. After detecting the liquid level, the dispensing probe stops a few mm below the liquid level and begins to aspirate the liquid. As the liquid level drops as it is aspirated, the probe tip is generally lowered to follow suit while aspirating the liquid.

[0020] This is because we want to avoid liquid adhering to the side of the probe as much as possible. If liquid remains on the side of the probe, the next time another liquid is aspirated, the different liquids may mix and affect the measurement results (commonly known as contamination). The probe is washed after each aspirate, but with recent advances in analytical technology, it cannot be denied that even slight contamination can affect the analysis results.

[0021] During liquid aspiration, the dispensing probe descends to follow the liquid surface, and the amount of liquid decreases, so the capacitance after contacting the liquid surface decreases slightly and monotonically. After the probe tip contacts the liquid surface, the capacitance is measured for a certain period of time (on the order of several hundred milliseconds), and the average value is calculated.

[0022] Fig. 3 is a functional block diagram of the automatic analyzer, in which functions other than those for capacitance calculation are omitted.

[0023] FIG. 5 shows a schematic diagram of the change in the average capacitance after contact with the liquid when the same amount of sample from the same container is aspirated each time.

[0024] The experiment was carried out as follows: 1. A sample container was placed in the device and repeated measurements of the sample in that container were requested. 2. The dispensing probe repeatedly aspirated a fixed amount of liquid from the sample container and dispensed the entire amount of aspirated liquid into the reaction container. 3. The capacitance was repeatedly measured before and after contact with the liquid to confirm the relationship between the amount of liquid in the container and the capacitance. Actual measurements will be discontinuous points, but as this is a schematic diagram, they are shown as a continuous line.

[0025] First, as the remaining liquid in the container decreases, the average capacitance decreases. Furthermore, when there is a sufficient amount of liquid in the sample container (1), the sample decreases in the cylindrical portion. As the liquid volume decreases and approaches the hemispherical portion near the bottom of the container (2), the decrease in liquid height increases even if the same amount of sample is aspirated. In the hemispherical portion (3), the slope of the decrease in the average capacitance becomes more pronounced. Therefore, even if the same amount is aspirated repeatedly, the way in which the average capacitance decreases changes depending on the shape near the bottom of the container compared to when there is sufficient liquid. For example, the decrease in capacitance with each aspirate is greater.

[0026] By analyzing the change in the decrease pattern, it is possible to detect that the sample volume is only near the bottom of the container, i.e., that there may be a shortage of sample.

[0027] As one analysis method, a flowchart of an embodiment in which the average capacitance value is compared with the value at the time of previous suction is shown in FIG.

[0028] The dispensing mechanism's suction operation involves moving the probe over the sample container and then lowering it to perform suction (S1). In the case of a capacitance-type liquid level detection sensor, it determines whether the probe has come into contact with the liquid based on changes in capacitance (S2). If the sensor detects the liquid level, it determines that the probe has come into contact with the liquid and aspirates the sample (S3). If the sensor does not detect the liquid level, the probe does not perform the suction operation and issues a warning (S4).

[0029] Regardless of whether or not sample aspiration is performed, the time series data of the capacitance from the start of probe descent to the end of aspiration is stored as a log in the memory unit (S5).Based on the stored log, the average capacitance for a certain period after the probe comes into contact with the liquid is calculated (S6).

[0030] The calculated average capacitance is compared with the average capacitance from the previous aspiration of the same sample (S7). A threshold value is set for the magnitude of the change, and if the change is equal to or greater than the set value, it is determined that the decrease in capacitance is large, meaning that the sample is only remaining at the bottom of the container, and a warning is issued to inform the user that the remaining sample is low (S8).

[0031] If the amount of change is less than the set threshold, it is determined that there is no significant change in the decreasing trend of the capacitance, and that a sufficient amount of sample remains in the container, and the aspiration operation is terminated.

[0032] Regarding the comparison with the previous detection in S7 in the figure, the data from the immediately previous liquid surface contact or the average data from the most recent predetermined number of liquid surface contacts may be used.

[0033] The amount of change may also be stored in advance in the storage unit as a reference value.

[0034] The present invention can be implemented regardless of the type of specimen container, but to measure the remaining amount more accurately, a table relating the capacitance value and remaining amount for each container shape can be created in advance, and this table can be referenced when calculating the remaining amount.

[0035] Furthermore, the present invention can be applied to liquids other than specimens, such as reagents, as measurement targets. If a possible specimen shortage is detected, an alarm can be issued to notify the user of this.

[0036] Furthermore, if the amount of liquid in the container can be determined from the capacitance, it is possible to display the amount of liquid in the container on the screen of the device operation unit.

[0037] The amount may be expressed as an absolute amount or as a percentage.

[0038] In order to determine whether or not there is a shortage of liquid by comparing the capacitance with the capacitance at the most recent time of contact with the liquid, it is preferable to store the capacitance for each contact with the liquid as a log.

[0039] The data to be stored may be time-series data of capacitance, or data processed from the time-series data to determine the remaining amount of liquid.

[0040] The data used for the determination need not necessarily be the capacitance while the probe is in contact with the liquid in the container, but may be the amount of change in capacitance when the capacitance detection unit comes into contact with the liquid surface.

[0041] According to the present invention, an automatic analyzer can be provided that can determine the remaining amount of sample without adding any additional components other than a capacitance type liquid level detection sensor, such as a camera that captures an image of the liquid level.

[0042] 100 Automatic analyzer 101 Transport rack 102 Sample container 104 Incubator 105 Reaction container 106 Transport mechanism 107 Tip holding member 108 Stirring mechanism 109 Disposal hole 110 Mounting position 111 Reagent disk 112 Cover 113 Cleaning mechanism 114, 115 Probe 116 Detection unit 117 Rack transport line 118 Reagent container 119 Tip 120 Storage section 201 Rotating shaft 202 Arm 203 Probe 204 Probe tip (capacitance detection section) 205 Electrode facing the capacitance detection section.

Claims

1. a probe for aspirating liquid from a container; a capacitance measuring mechanism for measuring a capacitance between the probe and the liquid contained in the container; In an automatic analyzer comprising: An automatic analyzer characterized by comprising a calculation means for calculating the amount of the liquid based on the average value of the capacitance measured by the capacitance measurement mechanism for a predetermined time after the probe comes into contact with the liquid contained in the container.

2. 2. The automatic analyzer according to claim 1, a storage unit that stores in advance the relationship between the average capacitance and the amount of liquid; The automatic analyzer is characterized in that the calculation means calculates the liquid volume based on the relationship.

3. 3. The automatic analyzer according to claim 2, The automatic analyzer according to claim 1, wherein the relationship between the average capacitance value stored in the memory unit and the amount of the liquid varies depending on the shape of the container.

4. 2. The automatic analyzer according to claim 1, The automatic analyzer is characterized in that the calculation means calculates the remaining amount of liquid contained in the container based on the change in the average value of the capacitance measured by the capacitance measurement mechanism at different suction times for a predetermined period of time after the probe comes into contact with the liquid contained in the container.

5. 2. The automatic analyzer according to claim 1, The automatic analyzer is characterized in that the calculation means calculates the change in the remaining amount of liquid contained in the container based on the change in the average value of the capacitance measured by the capacitance measurement mechanism at different suction times over a predetermined period of time after the probe comes into contact with the liquid contained in the container.

6. 2. The automatic analyzer according to claim 1, An automatic analyzer characterized by having a detection means for detecting that the remaining amount of liquid contained in the container is low based on the slope of the change in the average value of the capacitance measured by the capacitance measurement mechanism for a predetermined period of time after the probe comes into contact with the liquid contained in the container during different suction operations.

7. 7. The automatic analyzer according to claim 6, An automatic analyzer characterized by comprising an alarm mechanism that, when the detecting means detects that the remaining amount of the liquid is low, notifies the user of this fact.

8. 6. The automatic analyzer according to claim 5, An automatic analyzer comprising a display means for displaying the remaining amount calculated by the calculation means.

9. a probe for aspirating liquid from a container; a capacitance measuring mechanism for measuring a capacitance between the probe and the liquid contained in the container; In an automatic analyzer comprising: a calculation means for calculating the amount of the liquid contained in the container based on the value of the capacitance measured by the capacitance measurement mechanism when the probe comes into contact with the liquid; a storage unit that stores in advance the relationship between the capacitance value and the amount of the liquid; the calculation means calculates the liquid volume based on the relationship; An automatic analyzer according to claim 1, wherein the relationship between the capacitance value stored in the memory unit and the amount of the liquid differs depending on the shape of the container.