JP3322604B2 - Dispensing tip - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dispensing method which enables detection of whether or not a chip mounted on a nozzle of a multiple pipetter or the like has been immersed in a liquid sample and allows the inside of the chip to be visually confirmed. For chips.

[0002]

2. Description of the Related Art Conventionally, in the fields of biochemistry, biotechnology, medicine, clinical examination, etc., it is necessary to quantitatively dispense a liquid sample such as a reagent at a level of several milliliters to 1 microliter. A dispensing device such as a piston-type pipettor capable of accurately dispensing a fixed amount is used.

[0003] A tip of such a dispensing apparatus is mounted with a chip which sucks and discharges a liquid sample by directly touching the same, and mixing of the different liquid samples is prevented by exchanging tips.

As shown in FIG. 6, the tip of the chip 2 is inserted into the liquid sample 3 and the tip of the chip 2 is sucked in.
The liquid sample 3 is sucked into the chip 2 by sucking the air inside. Thereafter, the dispensing device is moved onto the sample container to send air to the chip 2, thereby discharging the liquid sample 3 in the chip 2 to the sample container.

At this time, when the chip 2 is immersed in the liquid sample 3, the liquid sample 3 naturally adheres to the outer surface of the chip 2, so that it may be difficult to dispense an accurate amount. is there. This is particularly remarkable when the viscosity of the liquid sample 3 is high.

Therefore, it has been proposed to address the above-mentioned problem by minimizing the amount of the tip of the chip 2 immersed in the liquid sample 3 as much as possible.

That is, the tip 2 is formed of a conductive resin (a resin containing carbon or the like), and the place where the tip 2 is immersed in the liquid sample 3 is electrically detected to start suction. At this time, since the liquid surface of the liquid sample 3 changes with the suction, the tip 2 is lowered based on the electric signal to control the amount of the chip 2 immersed in the liquid sample 3.

[0008]

However, since a chip made of a conductive resin is opaque, it cannot be visually confirmed whether or not the chip is actually sucked. There is a problem that can not be confirmed even if there is. Further, there has been a problem that such a conductive resin chip is expensive.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an inexpensive dispensing tip capable of detecting the surface of a liquid sample and confirming the inside of the tip.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is to form a chip mounted on a nozzle of a dispensing device and used for dispensing a liquid sample from a transparent member.
In addition, the tip aspirates the liquid sample from the head attached to the nozzle, and faces the tip in the longitudinal direction up to the tip for discharging.
A conductive member is extended to detect whether the tip of the chip has reached the surface of the liquid sample based on whether the tip of the chip is in contact with the liquid sample and the two conductive members conduct. It is characterized by having done.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a top view of a chip according to the present invention, and FIG.
FIG.

The chip 10 is made of a transparent material such as polypropylene, polycarbonate, or heat-resistant silicon rubber, and has a head 11 and a liquid portion 12 and has a substantially conical appearance. A hole 14 through which the liquid sample enters and exits is provided.

The tip 10 has a hole 1 from the head 11.
The two conductive members 15a and 15b are extended to face each other.

The conductive materials 15a and 15b include:
A chemically stable material such as carbon, copper, titanium, tantalum, tungsten, and gold can be appropriately selected according to the purpose.

The conductive members 15a and 15b may be exposed on the surface of the chip 10.
Only the conductive members 15a and 15b in the holes 1 and 14 are exposed to the surface, and the conductive members 15a and 15b in the liquid portion 12 are exposed.
15b may be embedded. By adopting a configuration in which the conductive members 15a and 15b in the liquid portion 12 are embedded, the influence of the liquid sample attached to the outer surface of the chip 10 can be removed, and thus there is an advantage that the liquid level detection sensitivity can be increased. .

In the above description, the conductive members 15a,
Although the configuration in which the chip 15b is embedded in the chip 10 has been described, the chip 15 may be provided on the outer surface of the chip 10 as shown in FIG.

Next, the dispensing process of the liquid sample while detecting the liquid level using the chip 10 having such a configuration will be described.

First, as shown in FIG. 4, the tip 10 is mounted on the nozzle 20 of the dispensing apparatus. At this time, the nozzle 20 is provided with electrodes 21 and 22 and the electrodes 21 and 22 are provided.
2 and conductive members 15a, 15b provided on chip 10
The position of the chip 10 is checked and mounted so that the and are electrically in contact with each other.

In order to facilitate the positioning of the chip 10, the chip 10 and the nozzle 20 may be provided with a groove for positioning.

FIG. 5 shows a liquid level detection circuit. The liquid level detection circuit has a power supply 40,
Are connected to the electrode 22 via the resistor 41, and the other output terminal is connected to the electrode 21.

A capacitor 42 and a resistor 43 are connected to the electrode 22 and input to the amplifier 45, and are connected to the output of the amplifier 45 output via the diode 46 via the resistor 44. On the other hand, the electrode 21 is input to the amplifier 45.

When the liquid sample 31 in the sample container 30 is sucked using the chip 10 connected to the liquid level detection circuit, the nozzle 20 is gradually brought closer to the liquid level. When the tip of the tip 10 comes into contact with the liquid surface, the conductivity of the liquid sample 31 causes the electrodes 21 and 22 to conduct, so that the partial pressure value of the resistance between the electrodes 21 and 22 and the resistance 41 changes. .

Therefore, the input voltage of the amplifier 45 changes,
The output changes depending on whether or not there is conduction between the electrode 21 and the electrode 22, that is, whether or not the tip 10 has contacted the liquid surface of the liquid sample 31.

Thus, the position of the nozzle 20 is controlled so that the signal output from the amplifier 45 maintains a predetermined value, and the liquid sample 31 is sucked.

Since the tip 10 is transparent except for the conductive members 15a and 15b as described above, it is checked whether or not the liquid sample has been sucked, and whether or not foreign matter such as dust has entered the tip 10. It will be possible to check.

[0026]

As described above, the surface of the liquid sample is detected based on the conduction state of the two conductive members, and since the portions other than the conductive member are formed of a transparent member, it is determined whether or not the liquid sample has been sucked. It is possible to check whether or not foreign matter such as dust is in the chip.

[Brief description of the drawings]

FIG. 1 is a top view of a chip applied to the description of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a cross-sectional view of a chip having another configuration.

FIG. 4 is a diagram showing a state in which the chip according to FIG. 1 is attached to a nozzle and a liquid sample is sucked.

FIG. 5 is a liquid level detection circuit diagram.

FIG. 6 is a diagram applied to the description of a problem.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Chip 11 Head 12 Liquid part 14 Hole 15a, 15b Conductive member

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-8-338849 (JP, A) JP-A-10-16,738 (JP, A) JP-A 63-96457 (JP, U) JP-A 7-96457 39931 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01L 3/02 G01N 1/00 101 B01J 4/00-4/02

Claims (1)

(57) [Claims] A chip mounted on a nozzle of a dispensing apparatus and used for dispensing a liquid sample is formed of a transparent member, and a liquid sample is suctioned from a head of the chip mounted on the nozzle. A dispensing tip, wherein two conductive members are extended in a longitudinal direction of a tip end for discharging.