JP3647023B2 - Dispensing device and method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dispensing device, and more particularly to a dispensing device having a function of temporarily storing a used nozzle tip and reusing it.
[0002]
[Prior art]
The methods related to the nozzles of conventional dispensing apparatuses are roughly classified into a non-disposable type and a disposable type. According to the former, contamination between the reagents and samples to be dispensed becomes a problem, and when nozzle cleaning is performed for that purpose, there is a problem of processing efficiency. According to the latter, such a problem can be solved, but since a new nozzle tip is used for each dispensing, there are problems such as an increase in the amount of discarded materials and running costs.
[0003]
In view of this, a type of dispensing device has been proposed in which the used nozzle tip is temporarily stored and the used nozzle is reused when the same reagent or sample needs to be re-dispensed. According to such an apparatus, the amount of discarded items can be minimized while avoiding the problem of contamination.
[0004]
[Problems to be solved by the invention]
However, in the type of dispensing device that reuses the tip as described above, the liquid (reagent, sample) inevitably remains in the stored nozzle tip. This is due to adhesion to the inner surface of the chip, excess amount at the time of liquid suction (excess suction amount for increasing dispensing accuracy), and the like. Then, the nozzle tip end may be clogged due to the drying of the remaining liquid. If the next dispensing is performed with such clogging occurring, proper dispensing cannot be performed, causing a problem in dispensing accuracy.
[0005]
Here, the clogging includes not only a completely closed state but also a case where residual liquid having a high viscosity adheres to the inner surface of the tip of the nozzle tip, which causes suction resistance. In addition, even if the clogging is eliminated at the time of the next suction, if a suction amount error occurs, there is a problem in dispensing accuracy.
[0006]
Therefore, it is conceivable to manage the evacuation time for each evacuated nozzle chip and uniformly discard the evacuation time, but clogging is caused not only by the amount of remaining liquid but also by environmental factors such as temperature and humidity. Such time management is not certain because it depends.
[0007]
Note that it is conceivable that the remaining liquid is ejected before the used nozzle tip is stored, but in this case, the dispensing step is increased and the operation efficiency is lowered. In addition, if ejection is not performed properly, there is a problem of contamination due to scattering of liquid. Therefore, basically, the used nozzle tip is often stored while leaving the remaining liquid as it is. On the other hand, even when the remaining liquid is ejected, the remaining liquid still remains in the chip due to the wettability of the liquid on the inner surface of the chip.
[0008]
The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to determine a defect when a used nozzle tip is used and to improve the reliability of dispensing.
[0009]
[Means for Solving the Problems]
(1) In order to achieve the above object, the present invention is connected to a tip rack for temporarily holding used nozzle tips, a nozzle base to which the nozzle tips are detachably attached, and the nozzle base. A dispensing drive unit that transmits discharge force and suction force to the nozzle base, and has a function of saving and storing the used nozzle tip in the tip rack and reusing the used nozzle tip. In the dispensing apparatus, a pressure sensor for detecting a pressure in the nozzle base, a remounting control means for performing operation control of a remounting process for mounting the used nozzle tip to the nozzle base, and in the remounting process the determination means a failure of the used nozzle tip based on the output of the pressure sensor, only contains the reseat control means, the used Nozuruchi' The prior together or in attachment to nozzle base, characterized in that depressurizing the inside of the nozzle base of.
[0010]
According to the above configuration, prior to the reuse of the used nozzle tip, it is possible to determine the defect of the nozzle tip based on the pressure in the nozzle base at the time of remounting, so that the dispensing accuracy can be guaranteed and the reliability of the dispensing device Can be enhanced. Examples of the defect include clogging (clogging) at the tip of the nozzle tip and an increase in the viscosity of the remaining liquid in the nozzle tip (half clogging). In determining the failure, one or more of a pressure value, a pressure gradient, a pressure peak, and the like can be referred to.
[0011]
Desirably, before Symbol judging means determines failure of the used nozzle tip from the magnitude of the output of the pressure sensor during the pressure reduction. According to this configuration, when the pressure inside the nozzle base is reduced, the detected pressure fluctuates (pressure drop) depending on the nozzle tip opening and the state of the remaining liquid inside the nozzle. Judgment is possible.
[0012]
When re-installing a used nozzle tip, the residual liquid in the tip may be ejected as the internal volume of the tip is reduced. Although it is desirable, if the above-described nozzle chip defect determination is performed together with the decompression step, the processing efficiency can be improved.
[0013]
Preferably, the determination means determines a defect of the used nozzle tip by comparing the pressure of the pressure sensor with a reference value. As will be described later, it is desirable that the reference value be configured to be variably set according to various conditions (for example, properties such as the viscosity of the remaining liquid, liquid amount, chip type and volume).
[0014]
Desirably, the said determination means determines the clogging in a tip part as a defect of the said used nozzle tip. When such a clogging occurs, a large dispensing error occurs, so that it is particularly necessary to detect the clogging.
[0015]
Preferably, the determination unit variably sets the reference value according to the remaining amount of liquid in the used nozzle tip. Even if the viscosity does not change, the pressure value changes according to the remaining amount, so that the reference value for determination is variably set accordingly.
[0016]
Preferably, the remounting control unit performs control to cope with the defect of the used nozzle chip when the defect of the used nozzle chip is determined. Preferably, the used nozzle tip is discarded in the control for dealing with the defect. After this disposal, a new nozzle tip is installed.
[0017]
(2) In order to achieve the above object, the present invention includes a step of removing and storing a used nozzle tip to be reused from the nozzle base, and storing the used nozzle tip in the nozzle base. in a step of remounting said at remounting, viewing including the step of determining to the clogging defect due to residual liquid of the used nozzle tip monitors the pressure, of the nozzle base further during the remounting Including a step of changing the pressure in the nozzle base, and in the step of changing the pressure in the nozzle base, the inside of the nozzle base is depressurized at least before the mounting is completed. Preferably, the step of determining the clogging failure is performed in a state where the inside of the nozzle base is decompressed.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.
[0020]
FIG. 1 shows a preferred embodiment of a dispensing apparatus according to the present invention, and FIG. 1 is a conceptual diagram showing the overall configuration thereof. This dispensing apparatus has a function of saving and storing once used nozzle tips and reusing such used nozzle tips. Of course, such reuse is basically performed when the liquids to be dispensed are the same.
[0021]
In FIG. 1, the nozzle base 10 is freely transported in a three-dimensional direction by a nozzle transport unit 28. The nozzle base portion 10 is made of, for example, a pipe-shaped metal member, and the tip portion thereof constitutes a tip fitting portion. A nozzle tip 12 made of, for example, a resin is detachably attached to the tip portion. Specifically, the tip of the nozzle base 10 is attached to the upper end opening of the nozzle tip 12. In FIG. 1, a used nozzle chip (evacuation chip) that is saved as the nozzle chip 12 is shown. The nozzle tip 12 contains the liquid 8 remaining in the previous dispensing. Such a remaining liquid may correspond to an excess amount of excess sucked at the time of the previous dispensing, or may be a liquid adhering to the inner surface of the chip.
[0022]
In FIG. 1, the tip rack 14 is for saving and storing used nozzle tips, and the used nozzle tips 12 are held on the tip rack 14. That is, in the state where the previous dispensing is completed, the nozzle base 10 is transported, and the nozzle tip 12 is moved from the nozzle base 10 by the action of a tip remover (not shown) while the nozzle tip 12 is held by the tip rack 14. Removed.
[0023]
Incidentally, reference numeral 15 in FIG. 1 denotes a chip rack holding a new nozzle chip. Of course, new nozzle chips and used nozzle chips may be held and managed on the same chip rack. The control unit 36 described later manages the properties (whether new or used) of each nozzle tip and the holding position corresponding to the type of liquid to be dispensed. Incidentally, the dispensing device is provided with a container containing a reagent or sample as a liquid or a disposal tray for discarding used chips, but is not shown.
[0024]
One end of an air tube 16 is connected to the upper end of the nozzle base 10, and the lower end thereof is connected to a dispensing pump 18. The dispensing pump 18 is constituted by a syringe 20 and a piston 22 in the present embodiment. By advancing and retracting the position of the piston 22 in the syringe 20, a suction force or a discharge force is exhibited. The operation of the dispensing pump 18 is controlled by the control unit 36 via the pump driving unit 26.
[0025]
A branch portion is formed in the air tube 16, and a pressure sensor 24 is connected to the branch portion. The pressure sensor 24 is a detector for indirectly detecting the pressure in the nozzle base 10. Of course, the pressure sensor 24 may be provided directly to the nozzle base 10, or the pressure sensor 24 may be provided to the dispensing pump 18. The detection signal of the pressure sensor 24 is output to the comparator 32 via the sensor signal output circuit 30.
[0026]
The comparator 32 is a means for comparing the pressure value detected by the pressure sensor 24 with a predetermined reference value and determining when the pressure value falls below the reference value. The comparison result is output to the control unit 36. The control unit 36 determines clogging or chip failure based on the comparison result of the comparator 32, and controls disposal / replacement of used nozzle chips, alarm output to the outside, and the like as necessary. Of course, you may make it perform the washing | cleaning operation | movement etc. which eliminate clogging as needed.
[0027]
A plurality of reference values corresponding to various conditions are stored in the memory 34, and any one of the reference values is output from the memory 34 by the selection of the control unit 36. For example, it is desirable to select the reference value according to conditions such as the environmental conditions such as the viscosity and remaining amount of the liquid 8, the form and type (including size), temperature, and humidity of the nozzle tip 12.
[0028]
FIG. 2 shows the clogging detection principle. Reference numeral 200 indicates a lowering operation period of the nozzle base 10, and the nozzle base 10 is pulled downward from above the used nozzle tip and is press-fitted into the tip portion or the upper opening of the nozzle tip 12. On the other hand, reference numeral 202 denotes a suction operation period. The suction operation is started when the nozzle tip 12 is mounted on the nozzle base 10, and the suction state is maintained for a certain period of time after both of them are fitted. The
[0029]
Here, looking at the pressure waveform, in the case of a normal nozzle tip denoted by reference numeral 100, the pressure in the nozzle base 10 is reduced from the atmospheric pressure with suction, but the pressure reduction itself is not so large. After completion of the suction operation period 202, the pressure will soon return to atmospheric pressure. On the other hand, when the viscosity of the remaining liquid is increased, a pressure waveform indicating a half-clogged state as indicated by reference numeral 102 is obtained. That is, a steep decompression curve is formed from the start of suction, and the negative peak of the pressure increases compared to the normal state (see reference numeral 100). Further, in the clogged state indicated by reference numeral 104, the pressure waveform steeply slopes in the pressure reducing direction immediately after the start of suction, and the pressure reducing state in the nozzle base 10 is maintained at a low value even after the suction operation is completed. . Therefore, in the present embodiment, the predetermined reference value 106 is compared with the pressure value, and when the reference value 106 falls below the pressure value, a defective used nozzle tip is determined. As described above, it is desirable that the reference value 106 is variably set according to various conditions.
[0030]
Incidentally, if the suction operation is started before the nozzle base 10 is mounted on the used nozzle tip 12, it is possible to avoid the problem of the ejection of liquid accompanying the decrease in the internal volume during the mounting. Therefore, if the suction operation is started before the actual fitting, the pressure waveform is monitored accordingly, and the chip failure is determined when the pressure waveform is lower than the reference value 106, the liquid can be prevented from being ejected. And chip defect detection can be achieved at the same time.
[0031]
If a plurality of reference values are set in stages, it is possible to discriminate clogging states, and for example, it is possible to identify half clogging, complete clogging, and the like.
[0032]
FIG. 3 shows the relationship (correlation) between the dispensing amount and the minimum pressure value in the tip when the used nozzle tip (retraction tip) is mounted. In the figure, the horizontal axis indicates the data number, where the data number is from 1 to 50. The vertical axis on the left of the vertical axis represents the actual dispensing volume for the target dispensing volume of 40 μl. In other words, if there is clogging or the like in the chip, even when a predetermined amount of liquid is sucked and discharged, the target suction amount cannot be sucked at the first suction, resulting in a deviation in the discharge amount. It ends up.
[0033]
The vertical axis on the right side in FIG. 3 indicates the minimum pressure value in the nozzle tip when the used tip is attached.
[0034]
As shown in FIG. 3, it can be understood that there is a close correlation between the dispensed amount and the minimum pressure value regardless of the evacuation time. In particular, if the evacuation time is long, clogging is likely to occur, and as a result, there is a problem that the actual dispensing amount is reduced. When such a phenomenon occurs, the minimum pressure value also decreases. Therefore, if such a minimum pressure value or the pressure value itself is monitored, the deviation of the actual dispensing amount from the target dispensing amount, that is, dispensing. There is an advantage that an error can be detected in advance. Considering the reference value according to the relationship shown in FIG. 3, for example, the reference value can be set to 1500 pa or the like.
[0035]
The overall operation of the dispensing apparatus described above will be described. First, when dispensing a certain liquid, a new nozzle tip is first mounted on the nozzle base 10 from the tip rack 15 to dispense the liquid. Is carried out. Before dispensing the next liquid, the nozzle chip 12 mounted on the nozzle base 10 is moved onto the chip rack 14, and then a new nozzle chip is mounted on the nozzle chip 12 for another liquid. Is dispensed. Immediately thereafter or after dispensing a plurality of liquids, when dispensing the same liquid as the liquid remaining in the used nozzle chip, the used nozzle chip 12 is mounted on the nozzle chip 12 again. At the time of the mounting, as shown in FIG. 2, the suction operation is executed, and the pressure in the nozzle base 10 is monitored including the period of the suction operation or before and after.
[0036]
In that case, if the pressure curve shows an abnormal tendency, it is possible to determine the clogging inside the defective nozzle clog or the clogging of the tip with the tendency. If such a determination is made, the used nozzle tip is discarded without being used for dispensing. On the other hand, if no abnormality is detected by monitoring the pressure curve, the used nozzle tip is reused for dispensing. Then, if necessary, the nozzle chip is saved again on the chip rack 14, and the nozzle chip is reused as necessary.
[0037]
According to the above embodiment, when the liquid remains in the used nozzle tip and the liquid is solidified or semi-solidified, the next dispensing is hindered. By monitoring the pressure, there is an advantage that the abnormality can be detected in advance and the occurrence of dispensing errors can be prevented. In the above embodiment, the pressure value at each time is compared with the reference value. However, as can be understood from FIG. 3, for example, the minimum pressure value and the reference value can be compared. The abnormality of the used nozzle tip may be determined by comparing the pressure gradient, that is, the inclination of the pressure curve with a predetermined inclination reference value.
[0038]
【The invention's effect】
As described above, according to the present invention, there is an advantage that abnormality can be detected and dispensing errors can be avoided when the used nozzle tip is reused.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a preferred embodiment of a dispensing apparatus according to the present invention.
FIG. 2 is a diagram for explaining the principle of detecting nozzle clogging.
FIG. 3 is a diagram for explaining a relationship between an actual dispensing amount and a minimum pressure value.
[Explanation of symbols]
10 nozzle base, 12 nozzle tip (used nozzle tip), 14, 15 tip rack, 16 air tube, 18 dispensing pump, 20 syringe, 22 piston, 24 pressure sensor, 32 comparator, 34 memory, 36 control unit.

Claims (9)

A tip rack for temporarily holding used nozzle tips;
A nozzle base to which the nozzle tip is detachably mounted;
A dispensing drive unit connected to the nozzle base and transmitting a discharge force and a suction force to the nozzle base;
Including
In the dispensing apparatus having the function of retreating and storing the used nozzle tip in the tip rack and reusing the used nozzle tip,
A pressure sensor for detecting the pressure in the nozzle base;
Remounting control means for performing operation control of a remounting process for mounting the used nozzle tip to the nozzle base;
Determination means for determining a defect of the used nozzle chip based on an output of the pressure sensor in the remounting step;
Only including,
The remounting control means depressurizes the inside of the nozzle base together with or prior to mounting of the used nozzle tip to the nozzle base . The apparatus of claim 1.
Before Symbol judging means, the dispensing apparatus characterized by determining a failure of the used nozzle tip from the magnitude of the output of the pressure sensor during the pressure reduction. The apparatus of claim 2.
The dispensing device compares the pressure of the pressure sensor with a reference value to determine a defect of the used nozzle tip. The apparatus of claim 3.
The dispenser according to claim 1, wherein the determination means determines clogging at a tip end portion as a defect of the used nozzle tip. The apparatus of claim 3.
The dispensing device variably sets the reference value in accordance with the remaining amount of liquid in the used nozzle tip. The apparatus of claim 1.
The dispensing apparatus according to claim 1, wherein the remounting control unit performs control to deal with the defect of the used nozzle tip when the defect of the used nozzle chip is determined. The apparatus of claim 6.
In the control for dealing with the defect, the used nozzle tip is discarded. Removing the used nozzle tip to be reused from the nozzle base and saving it;
Reattaching the used nozzle tip to the nozzle base;
Monitoring the pressure in the nozzle base at the time of remounting and determining clogging failure due to residual liquid in the used nozzle tip; and
Only including,
Furthermore, the step of changing the pressure in the nozzle base at the time of the remounting,
In the step of changing the pressure in the nozzle base, the inside of the nozzle base is depressurized at least from before the mounting to the completion of the mounting . The method of claim 7, wherein
A dispensing method , wherein the step of determining the clogging failure is performed in a state where the inside of the nozzle base is decompressed .

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