JPS62151760A - Liquid heating unit for sample inspection system - Google Patents

Abstract

PURPOSE:To reduce the size of a heating unit and also simplify its constitution, and to improve the temperature accuracy by providing a positive temperature coefficient thermistor (PTC element) which heats liquid and a power source which applies a voltage to the PTC element. CONSTITUTION:A reagent 4 is dispensed to a reaction cell from a nozzle 6 formed atop of the reagent dispensing tube 3 of a sample inspection system. The PTC element 5 is fitted externally onto this tube 3 and the voltage is applied from the power source 1 through an ammeter 2. The PTC element 5 is made of oxide semiconductor ceramic consisting principally of barium titanate, and has a Curier temperature which is optionally settable by material composition and increases in electric resistance abruptly from the temperature. For the purpose, when a constant voltage is applied to the PTC element 5 while its circumferential condition is made constant, a current corresponding to the initial resistance flows and the element heats itself to rise in temperature. When the temperature reaches the Curier temperature, the resistance increases abruptly and the current is reduced, so that generated electric power and surface temperature become constant. Consequently, neither a temperature sensor nor a temperature control circuit is required and the reagent is preheated accurately in a short time.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a sample testing system that injects a liquid sample and a reagent into a reaction cell and tests the mixed solution (reaction solution) at a predetermined temperature. This relates to the liquid heating unit used.

[Technical background of the invention and its problems]

Generally, in this type of specimen testing system, it is necessary to maintain a constant temperature of the reaction system in order to obtain data reproducibility. The constant temperature system of the sample testing unit includes a constant temperature system using water as a medium and a constant temperature system using air as a medium. Constant-temperature systems that use water as a medium are generally used, but there are disadvantages in that contamination of the constant-temperature water adversely affects data obtained by direct photometry, and maintenance is complicated. On the other hand, a constant temperature system using air as a medium has the advantage of maintaining a clean state.

However, when air is used as a medium, the heating temperature is slow due to poor thermal conductivity compared to water, and for this reason, when air is used as a medium, a heating unit is required as a heating aid means.

Conventional heating units include those that preheat reagents and the like to be added, and those that preheat a stirrer to homogenize the reaction solution.

However, these conventional heating units use heaters, constant-temperature water, etc. as their heating mechanism, so it is necessary to install a temperature sensor and temperature control circuit to prevent overheating, which results in inadequate responsiveness. Another disadvantage is that the unit itself becomes large and cannot necessarily be installed in the required location.

Further, in the case where the stirrer is preheated, the stirrer is simply immersed in constant temperature water or the like in advance, which poses a problem in the temperature accuracy of the reaction liquid.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and it is possible to achieve miniaturization by eliminating the need for a temperature sensor or a temperature control circuit, and also to improve temperature accuracy even when a stirrer is used. The purpose is to provide a liquid heating unit that can.

[Summary of the invention]

The outline of the present invention for achieving the above object is to inject a liquid sample and a reagent into a reaction cell and test the liquid mixture at a predetermined temperature. The device is characterized by comprising a PTC element/element that heats the PTC element, and a power source that applies voltage to the PTC element.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the invention.

In FIG. 1, reference numeral 3 denotes a reagent dispensing tube in the sample testing system, and a reagent 4 is dispensed into a reaction cell (not shown) through a nozzle 6 formed at its tip. 5 is a cylindrical PTC element fitted onto the reagent dispensing tube 3, 1 is a power source, and 2 is an ammeter.

PTC element, that is, PTC thermistor (Positive
Temperature Coefficient T
hermistor (positive temperature coefficient thermistor) is an oxide semiconductor ceramic whose main component is barium titanate, and has a Curie temperature (resistance sudden change temperature, -20°C to +330°C) that can be set arbitrarily depending on the material composition. , there is a property that the electrical resistance increases rapidly from this temperature. Therefore, when a constant voltage is applied to the PTC element under constant ambient conditions, a current flows according to the initial resistance, the temperature rises due to self-heating, and when it reaches the Curie temperature, the resistance increases rapidly and the current decreases. The power generated and the surface temperature are kept constant.

In this example, the reagent dispensing tube 4 is a Teflon tube with an inner diameter of 1 mm, and a cylindrical PT tube is fitted to fit it.
As a result of applying a voltage of 16 V to the C element with an inner diameter of 1.2 fins, a length of 5.5 am, and a set temperature of 37°C, the reagent in the tube reached a temperature of 37° within 30 seconds after application, as shown in Figure 2.
C and then maintained at a constant temperature.

In this way, in this example, the reagent could be preheated accurately in a short time without requiring any temperature sensor or temperature control circuit.

FIG. 3 shows a second embodiment of the present invention, in which the same parts as those in FIG. 1 are given the same reference numerals.

In FIG. 3, 7 is a stirring bar made of a PTC element, and 8 is a reaction cell.

In this example, 400 μl of a reagent heated for 10 seconds in the same manner as in the first example described above was injected into a reaction cell containing 5 to 10 μβ of a sample and heated to 30°C, and then a stirrer was rotated at 60 rpm. As a result, as shown in Figure 4, the reaction solution 9 was removed in 15 seconds.
reached a predetermined temperature (37°C) and was then maintained at 37°C.

As described above, in this example, as in the first example, the reaction liquid could be heated in a short time and with good accuracy without requiring a temperature sensor or the like.

FIG. 5 shows a third embodiment of the present invention, in which the same parts as in the second embodiment are given the same reference numerals.

In FIG. 5, reference numeral 10 denotes a plate-shaped PTC element, which is formed on the side surface of the reaction cell 8. Reference numeral 11 denotes a light source, and the reaction state of the reaction liquid is inspected by detecting the light 12 emitted from the light source 11 and transmitted through the reaction liquid by a photometer (not shown).

FIG. 6 shows a fourth embodiment of the present invention, in which the same parts as in the third embodiment are given the same reference numerals.

In FIG. 6, 13 is a flow cell, 14 is a sample suction hole, 15 is a sample discharge hole, and 16 is an annular PTC element fitted onto the outside of the flow cell 13.

3 above. The fourth embodiment also applies to the first embodiment. Similar to the second embodiment, the reaction solution can be heated in a short time without requiring a temperature sensor or the like.

Although the embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above embodiments, and can be modified as appropriate within the scope of the gist of the present invention.

〔Effect of the invention〕

As detailed above, according to the present invention, since a PTC element for heating a liquid is provided in a sample testing system, a temperature sensor and a temperature control circuit are not required, and the heating unit can be downsized and simplified. It is also possible to improve temperature accuracy.

In addition, since the PTC element is made of ceramics, it can be formed into a fairly flexible shape, allowing it to be fitted to the area to be heated and heated efficiently, making it possible to obtain a heating state with good responsiveness and reducing analysis time. The time can be shortened.

Therefore, the present invention can serve as a powerful and efficient heating means particularly for air constant temperature systems in which temperature control such as heating time and temperature accuracy has been difficult in the past.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the first embodiment of the present invention, FIG. 2 is an explanatory diagram of the same action, FIG. 3 is a schematic diagram of the second embodiment, and FIG. 4 is an explanatory diagram of the same action. FIG. 5 is a schematic diagram of the third embodiment, and FIG. 6 is a schematic diagram of the fourth embodiment. ■...Power supply, 3...Reagent dispensing tube, 4...Reagent, 5.7, 10.16...PTC element, 8...Reaction cell, 9...Reaction liquid, 13. ...Flow cell. Agent Patent attorney Nori Chika Ken Nobuyuki Ogo Norio Time (μ time PA (butt) Condolence Figure 4 Figure 5 Figure 6

Claims (5)

[Claims] (1) Inject the liquid sample and reagent into the reaction cell,
A liquid heating unit for use in a sample testing system for testing these mixed liquids at a predetermined temperature, comprising: a PTC element for heating the liquid; and a power source for applying a voltage to the PTC element. Liquid heating unit for inspection systems. (2) The liquid heating unit for a sample testing system according to claim 1, wherein the sample testing system includes a reagent dispensing tube, and the PTC element is fitted onto the reagent dispensing tube. (3) The liquid heating unit for a sample testing system according to claim 1, wherein the PTC element is a stirrer that stirs the mixed liquid in the reaction cell. (4) A liquid heating unit for a sample testing system according to claim 1, wherein the PTC element is formed on a side surface of a reaction cell. (5) The liquid heating unit for a sample testing system according to claim 1, wherein the reaction cell is a flow cell, and the PTC element is fitted onto the flow cell.