JPH05236932A - Dna amplifying thermostatic device - Google Patents

Abstract

PURPOSE:To increase durability and safety of DNA amplifying thermostatic device by improving a member of a conventional cartridge type sheath heater. CONSTITUTION:The objective DNA amplifying thermostatic device is provided with a heater obtained by impregnating a heat-resistant insulating material into a hole of a porous supporting rod 1 for heating wire 2 of a cartridge type sheath heater or applying the insulating material to the hole to prepare a heating part and sealing the heating part in a jacket 3 together with inorganic insulator particles 4 impregnated or coated with an insulating material such as silicone resin.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention improves a heater in a DNA thermostatic device in which a cartridge type sheathed heater is used, and provides a device excellent in insulation, safety and durability.

2. Description of the Related Art A DNA amplification thermostat is required not only for rapid changes in temperature in order to improve the accuracy of experimental results and the efficiency of experiments, but also for the purpose of cryopreserving samples after experiments. Therefore, a wide operating temperature range of 0 ° C. to 100 ° C. is required. For this reason, the heater used for this heating needs to have high efficiency and high output. Conventionally, in these devices, a heater in which a heating wire is insulation-coated with a resin is often used. However, since these insulators are resin, they have a low heat resistance temperature, and when the output of the heater is increased to improve the heating performance, there is a problem that the heat stress causes the deterioration of the heating element and the insulator and separation between them. ..
In addition, when the peeling occurs, the infiltration of water or the like accelerates the oxidation of the heating wire and the reduction of the insulation resistance.

However, the cartridge-type sheathed heater is small in size and high in output, and is convenient for satisfying the requirements of the apparatus. The structure of an ordinary sheathed heater has a structure in which a heating wire is wound around an elongated support such as ceramic and is sealed with a filler of insulating material powder such as silica or alumina in a metallic hollow jacket. Since the output is high, the sealed portion is deformed due to thermal expansion and a gap is likely to be formed. On the other hand, a thermostatic device with a relatively low temperature may be used by setting it at a temperature lower than room temperature.
Condensation occurs in a high humidity environment. This moisture has entered the inside of the heater through the gap between the sealed parts, causing the insulation performance to deteriorate. Normally, the sheath heater is used at a fairly high temperature part, so these moisture boil when energized,
In many cases, evaporation does not result in lowering of insulation, which is not a practical problem. However, in the DNA amplification thermostat, the upper limit of the temperature is usually below the boiling point of water due to the nature of handling organic substances. Therefore, these moistures are accumulated inside the heater and deteriorate the life and insulation performance of the heater. That is, metal oxides such as silica and alumina, which are the fillers in the jacket, are extremely excellent in heat conduction and insulation performance and meet the requirements as a filler for heaters, but since they are hydrophilic, moisture is absorbed inside the crystal. It is easy to take in, and once water enters, it does not go out easily and accumulates with each use, resulting in deterioration of insulation performance. In addition, as a support for the heating wire, a sintered material of an inorganic material is often used, but since these are porous, they easily take in water. The present invention uses a cartridge-type sheathed heater, which eliminates the above-mentioned drawbacks, in a DNA amplification thermostatic device.

According to the present invention, alumina filled in the hollow jacket in the heater,
By forming a heat-resistant film of silicon resin or the like on the surface of powder particles of silica or the like, water repellency is given to prevent the intrusion of water inside the particles and make it easy for the water once intruded to the outside. As a countermeasure against the heating wire support, the pores of the porous support are filled with an insulating material such as silicone resin.

FIG. 1 is a perspective view of a cartridge type sheathed heater used for carrying out the present invention. The heating wire support rod 1 is made of a material obtained by sintering an inorganic material insulator, and is made by impregnating or coating a silicon resin on the material. The conventional heating wire 2 is spirally wound around the support rod 1 to lead out the lead wire 6 to form a heat generating portion. This heat generating portion is inserted into the jacket 3 which is a metallic hollow cylinder, and the inorganic insulating particles 4 impregnated or coated with a silicon resin are filled around the heat generating portion.
The lead wire 6 penetrates the jacket sealing portion and is drawn to the outside to complete the sheath heater 9. FIG. 2 is a perspective view of a DNA amplification thermostatic device equipped with a heater 9 used in the present invention, in which a heater 9 is laterally pushed into a holder 8 having good heat conductivity and having holes for arranging a large number of sample containers 7. Although only one heater 9 is shown as an example, it is customary to use a plurality of heaters 9 in consideration of the temperature distribution of the holder 8.

EFFECTS OF THE INVENTION By applying the above-mentioned treatment according to the present invention, it is possible to prevent the deterioration of the insulation performance with time under all conditions without modifying the conventional heater structure and without impairing the excellent characteristics of the heater itself. Therefore, a device having excellent durability and safety can be supplied.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a cartridge-type sheathed heater used in an embodiment of the present invention.

FIG. 2 is a perspective view of an embodiment of the present invention showing a state in which the heater is attached to the DNA amplification thermostatic device.

[Explanation of symbols]

 1: Heating wire support rod 2: Heating wire 3: Jacket 4: Inorganic insulator particles 6: Lead wire 7: Sample container 8: Holder 9: Heater

Claims (1)

[Claims] 1. A heating wire is formed by winding a heating wire around a heating wire support made of an inorganic material impregnated and coated with a heat resistant insulating material,
A DNA amplification thermostatic device comprising a cartridge-type sheathed heater in which the heat generating part is impregnated with a silicone resin or an insulating material similar thereto and enclosed in a jacket together with inorganic insulating particles applied.