JP2012093110A - Indicator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an indicator including a function capable of measuring how much time a predetermined temperature is applied to an object and a function capable of visually confirming application of temperature.SOLUTION: In an indicator 10, a first electrode 21 and a second electrode 22 are formed by mutually facing a coloring layer 15, the first electrode 21 is fixed on a fixing end 13, and the second electrode 22 is stuck to one side of a high molecular material sheet 14 and is movable. The high molecular material sheet 14 has characteristics of being crystallized and contracted and becoming opaque at a predetermined temperature. Since a distance between the electrodes 21 and 22 is changed by contraction following the crystallization of the high molecular material sheet 14, how much time the predetermined temperature is applied can be measured by reading a capacitance change and a color observation change of the coloring layer 15 can be confirmed through a window 18 of a film 16 by opacity of the high molecular material sheet 14, so that application of the predetermined temperature can be confirmed.

Description

  The present invention relates to an indicator, and more particularly to a thermal time integration type indicator designed to change color at a predetermined temperature and time.

  Foods have expiry dates, but these must be based on the expected storage conditions (temperature, humidity, sunlight, etc.) of a particular product. Therefore, the recommended storage state is also specified. However, since the actual storage state cannot be predicted and controlled, a time-temperature integration type indicator is required. In medical sterilization, a chemical indicator (CI) is used for visually confirming whether the temperature and time required for sterilization have been applied to the object to be sterilized. CI is generally formed by applying a pigment designed to change color at a sterilizable temperature and time (for example, when 121 ° C. is added for 20 minutes). So-called thermolabels that change color at a certain temperature cannot add such time.

  In a broad sense, an indicator is a display, indicator, indicator, indicator, indicator, indicator, indicator, and a wide range of objects to be measured. The type of time indicator that can be confirmed by discoloration or the like whether or not the necessary conditions are satisfied will be described.

  There are two types of time indicators. One considers not only time but also cumulative heat exposure applied to the object. This is accomplished by increasing the rate of change of the indicator with temperature as a function. Some of these indicators respond continuously to changes in temperature and others need to reach a threshold temperature so that they do not change color below a certain temperature. For example, in the case of an indicator used for sterilization work, it is necessary to take into account the accumulated time above the sterilizable temperature. These are generally called a “time-temperature indicator” or a “time-temperature indicator (TTI)”. The other is non-heat sensitive and provides a visual indication of elapsed time, commonly referred to as a “timer”.

  TTI indicates that a certain temperature or more has been applied for a certain period of time, such as deadline monitoring of items that are subject to corruption, such as food, food additives, biological materials, drugs, and cosmetics, and sterilization and sterilization in food and medical settings. This is very useful when an operator visually confirms. On the other hand, timers are useful for items that do not rot, such as alerts that need to be replaced, completed or updated. However, the above are application examples and are not limited thereto.

  The TTI and the timer are realized using a chemical reaction mechanism, a diffusion mechanism, and a capillary phenomenon mechanism. Since the time indicator can be visually confirmed by discoloration or the like, it can be evaluated that the user can judge a defect at a glance. However, when the evaluation is performed based on the degree of discoloration, there is a possibility of individual differences in the determination result because it is not a quantitative evaluation. Therefore, although quantification may be performed with a chromaticity meter, the chromaticity meter is expensive, and a large amount of objects is a heavy burden on the operator. Therefore, there is an indicator that accepts when a certain area is reached (Sumitomo 3M Co., Ltd.) based on the length of the area where the liquid is gradually infiltrated into the slender paper, for example, by utilizing capillary action instead of discoloration. With this method, quantitative evaluation is possible.

  In recent years, in order to ensure food and medical safety, traceability indicating that the distribution channel of goods can be traced from the production stage to the final consumption stage or the disposal stage has been regarded as important. There is an increasing need to capture information into a personal computer (hereinafter referred to as a PC). In such a case, it is the present situation that the operator often inputs the evaluation result of the indicator into the PC, and a radio frequency identification (RFID) is used for labor saving and unmanned work. I'm starting.

  RFID is a kind of automatic recognition / data carrier similar to a bar code or the like. In a barcode, a two-dimensional code optically reads, whereas an RFID uses radio waves. Compared with barcodes, RFID can be read without contact even with a shield such as a cardboard box, and can read multiple RFIDs at the same time, and generally can write / read hundreds of bits of data. There are advantages.

  By the way, there is a device called “Temperature Logger” as a device that records the temperature history of food, etc., and it has been used by food manufacturers for temperature management in the manufacturing process and distribution stage, but it is connected to a PC with a cable. If you don't, you won't be able to download data. In addition, the main body is large, which is an obstacle to collecting data frequently on a daily basis.

  On the other hand, RFID with a temperature sensor has the great convenience of being able to start / stop temperature collection / sucking data without contact, and it is downsized by using one chip (equipped with an RFID circuit / temperature sensor on one silicon chip). At the same time, there are expectations for cost reduction due to the reduction in the number of parts. An indicator based on a combination of a temperature sensor and an RFID is disclosed in Patent Document 1 and the like.

  FIG. 8 is a cross-sectional view of each example of the indicator described in Patent Document 1. The indicator shown in FIG. 8A includes a base material 1 having a microstructure surface that defines a plurality of channels 4, a conductive layer 2 disposed close to the microstructure surface of the base material 1, and an insulator layer 3. It consists of Channel 4 is designed so that the fluid travels at the desired constant speed. The conductive layer 2 is disposed in close proximity to the microstructure surface of the substrate 1, and comes into contact with the conductive or dielectric fluid moving through the channel 4 of the substrate 1, thereby causing resistance, current, It can be read as a change in voltage. The conductive layer 2 preferably has the patterning shown in FIG. When a dielectric fluid is used, an insulating layer 5 is provided as shown in FIG. 8B, and an electrode is formed on a part of the channel 4 so that it can be read as a capacitance change.

Special table 2008-516208 gazette

  However, the conventional indicator shown in the cross-sectional view of FIG. 8A has a complicated structure, and the other conventional indicator shown in the cross-sectional view of FIG. 8B has a more complicated structure.

  In addition, RFID with temperature sensor cannot be confirmed by visual inspection of the tag itself, and cannot be confirmed directly by an operator who does not have a reader. Therefore, rapid processing cannot be performed, and mistakes and misrecognition are possible. There is also sex. Desirably, the barometer for discoloration or the like is an RFID that can be confirmed by an operator's visual observation and can be taken out as an electrical signal.

  Here, the combination of TTI for visual observation and RFID with temperature sensor for electric signal extraction is also conceivable. However, the double cost is required, and if the correspondence between the two is not taken, the judgment standard becomes difficult and erroneous judgment is made. This is not preferable. Therefore, it can be said that the RFID built-in type TTI, in which the TTI information can be directly taken out as the output of the RFID, is the most desirable form. Moreover, assuming that it is used for each food or sterilization object, materials and production processes that can be produced at low cost are required.

  The present invention has been made in view of the above points, and provides an indicator that has a function of measuring how long a predetermined temperature has been applied to an object and a function of visually confirming that a temperature has been applied. The purpose is to do.

  Another object of the present invention is to provide an indicator having a simple configuration at low cost.

  In order to achieve the above object, an indicator of the present invention includes a base material, first and second electrodes formed opposite to each other above the base material, and one of the first and second electrodes. Or a polymer material sheet that is in contact with both, contracts at a predetermined temperature and has a cloudiness characteristic, and means for distinguishing the color that changes due to contraction and cloudiness of the polymer material sheet. It is characterized by providing.

  In order to achieve the above object, the indicator of the present invention is characterized by comprising reading means for reading the distance between the first and second electrodes as a change in electrical variable.

  According to the present invention, an indicator having both a function capable of measuring how long a predetermined temperature has been applied to an object and a function capable of visually confirming that the temperature has been applied is realized with a simple configuration. be able to.

It is sectional drawing of the initial state of the embodiment of the indicator of the present invention, top view of the initial state, sectional view of the final state, and top view of the final state. It is a figure explaining the manufacture process of Example 1 of the indicator of this invention. It is a figure which shows the transmitted light intensity with respect to the heating time at the time of a 130 degreeC isothermal heating of a polylactic acid (PLA) film. It is a figure which shows the shrinkage | contraction rate with respect to the heating time at the time of a 130 degreeC isothermal heating of a polylactic acid (PLA) film. It is a figure which shows an example of the isothermal crystallization process of PLA (LACEA H-100). It is the figure which showed the time of the exothermic peak by crystallization with respect to various isothermal assumptions in the material which added three types of nucleating agents, talc, clay, and mica to PLA (LACEA H-100). It is the external view of Example 2 which combined the indicator and RFID of this embodiment, and the block diagram of an example of an RFID chip. It is sectional drawing of an example of the indicator of patent document 1. FIG. It is a figure which shows the electrode part of the indicator of patent document 1. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  1 (a), (b), (c) and (d) are an initial state sectional view, an initial state top view, a final state sectional view and a final state of an embodiment of an indicator according to the present invention. The top view of is shown. As shown in FIGS. 4A to 4D, the indicator 10 according to the present embodiment has a base material 11, a colored layer 15 provided on the base material 11, and a colored layer 15 facing each other. The formed first electrode 21 and second electrode 22, the fixed end 13 for fixing the first electrode 21, the polymer material sheet 14 bonded to one side of the second electrode 22, and the polymer material It is a thermal time integration type indicator (TTI) composed of an adhesive 17 that fixes the sheet 14 on the colored layer 15 and an exterior film 16 that contains them. The exterior film 16 is provided with a window 18, and the transparent polymer film 14 on the colored layer 15 is clouded to reduce the transmittance, and the colored layer 15 viewed through the polymer film 14 appears whitened. Can be visually confirmed through the window 18.

  The first electrode 21 and the second electrode 22 are arranged opposite to each other to form a capacitor. The polymer material sheet 14 is transparent in the initial state, and has a characteristic of becoming clouded while contracting at a predetermined temperature. Since the distance between the electrode 21 and the electrode 22 changes as the polymer material sheet 14 contracts, a gap is opened between the electrode 21 and the electrode 22 as shown in FIG. The capacity between changes. Therefore, it is possible to measure how long the predetermined temperature has been applied to the indicator 10 by reading the capacitance change of the capacitor including the electrodes 21 and 22 by the reading means. In addition, since the electrode 21 and the electrode 22 are in an open state, it is confirmed that a predetermined temperature has been applied depending on the presence or absence of conduction between the electrode 21 and the electrode 22 if it is not necessary to see a change with time due to a change in capacitance. It is also possible.

  Further, since the polymer material sheet 14 becomes cloudy with crystallization due to the application of a predetermined temperature, the observer sees the colored layer 15 through the window 18 and the polymer material sheet 14 with the naked eye as shown in FIG. It appears whitened. In this way, the indicator 10 of the present embodiment has a mechanism that allows the temperature history to be recognized visually.

  Thus, according to the indicator 10 of the present embodiment, the fixed first electrode 21 and the movable second electrode 22 are opposed to each other to form a capacitor, and the movable second electrode 22 is arranged. Is crystallized at a predetermined temperature, and is bonded to one side of the rectangular shape of the polymer material sheet 14 having the characteristics of shrinkage and cloudiness. Since the distance between the electrodes 21 and 22 changes due to the shrinkage accompanying the crystallization of the polymer material sheet 14, it is possible to measure how long a predetermined temperature has been applied by reading the change in capacitance. At the same time, it is possible to realize a heat time integration type indicator that can confirm that the temperature has been visually added by exhibiting white turbidity. Further, it can be simply confirmed by the presence or absence of conduction between the electrodes 21 and 22. The indicator described in Patent Document 1 is different in this configuration, and according to the present embodiment, it can be realized with a simpler configuration.

  Note that the configuration in FIG. 1 is an example, and the arrangement and size of each component member are arbitrary. Since the crystallization stops when the temperature drops halfway, the result is shown when the predetermined temperature is applied for a predetermined time. Further, in the above embodiment, the polymer material sheet is in contact with the electrode 22, but it is also possible to replace the fixed end 13 and contact the electrode 21, or the electrode 21 and the electrode 22. It is also possible to configure so as to contact both. It is also possible to read a change in the distance between the electrode 21 and the electrode 22 as a voltage change, a current change, or a resistance change instead of a capacitance change. In short, the change in the distance between the electrode 21 and the electrode 22 may be read as a change in some electrical variable.

  Further, instead of providing the colored layer 15, one in which one or both of the polymer material sheet 14 and the base material 11 are colored is used, and at least a part of the cover 16 is sufficiently transparent. The transparency and coloring of the material 11 and the polymer material sheet 14 may be configured such that an observer can observe with naked eyes as the shrinkage and white turbidity of the polymer material sheet progress. The present invention only needs to have a means for distinguishing the color that changes in appearance as the color of the polymer material sheet changes with shrinkage and white turbidity.

  Next, Example 1 of the indicator 10 of the above embodiment will be described. The base material 11 is not particularly specified as a material to be used, but is preferably a sheet having a small thermal expansion. For example, glass, low thermal expansion polyimide film (Toray DuPont Co., Ltd .: Kapton EN-A type), low thermal expansion multilayer material (Hitachi Chemical Co., Ltd .: MCL-E-679F (R) )). Moreover, it is necessary to use a material having a sufficiently high glass transition temperature relative to the use temperature.

  The electrodes 21 and 22 may be any conductive sheet, such as a metal foil such as aluminum foil, a sheet of resin or paper integrated with the metal foil, a resin film containing metal powder, a non-woven fabric or cloth. It is considered that a powder coated with a powder has the same function. A metal piece or a member whose surface is conductively coated may be used.

  The fixed end 13 is preferably one that can firmly adhere to the base material 11 or the colored layer 15, and it is desirable to use an adhesive that has low thermal expansion. However, an adhesive that requires firing at such a high temperature that the polymer material sheet 14 is crystallized cannot be used. Therefore, for example, a precision UV curable adhesive (NTT Advanced Technology Co., Ltd .: AT4291A, 20 ppm / ° C., Hisol Co., Ltd .: Vitralit, 2665 27 ppm / ° C.) can be used.

  The polymer material sheet 14 is composed of a polymer material that becomes clouded by crystallization, and is selected according to the crystallization temperature and the crystallization speed. Examples of crystalline polymer materials include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polypropylene (PP), polyamide (PA), and polylactic acid (PLA). These include molecular weight, molecular weight distribution, molecular The crystallization temperature and speed vary depending on the structure and impurities. Although the crystallization rate can be increased by adding a nucleating agent, the initial state becomes white and the transmittance decreases, so that the amount added needs to be adjusted as appropriate.

  It is preferable that the colored layer 15 has a color in which a difference in color is easily confirmed depending on the degree of cloudiness of the polymer material sheet 14. The colored layer 15 may be formed on the base material 11 by printing, or the colored colored layer 15 may be bonded to the base material 11 and the base material 11 itself has a color. It does not have to be. Heat-resistant ink that does not fade, discolor, or change quality at the operating temperature can be used. Furthermore, it is desirable to use a heat conductive sheet that easily conducts heat, and carbon graphite sheet (Hibit Japan Co., Ltd.) is a heat conductive sheet with a small thermal expansion of 7.0 ppm / ° C and is suitable for this application because of its dark color. Yes. The gel-like heat-dissipating sheet has a large surface friction coefficient and may prevent the polymer material sheet 14 from crystallizing and contracting, and since it has high elasticity, it expands and contracts due to the crystallization of the polymer material sheet 14. This is not preferable because there is a possibility of canceling out the displacement due to.

  The exterior film 16 is preferably selected so as to cover a part or all of the article and is flexible, semi-rigid or rigid so as not to interfere with the operation of the article. It can be made from a material. It may be a monolithic structure or a multi-piece structure formed, for example, by joining two pieces, and can be made of an opaque material with a transparent window 18 that shows the degree of progress of turbidity due to crystallization. Although it may be made from a transparent material with a pattern, some should be free of the pattern in order to provide a window 18 that shows the degree of progression. Various methods including the lamination of the pressure-sensitive adhesive tape to the base material 11 are conceivable for bonding to the encapsulated article.

  Next, a specific example of the indicator of the present invention when polylactic acid (PLA) (Mitsui Chemicals, Inc .: LACEA H-100) is used as the polymer material sheet 14 will be described with reference to FIG.

  As shown in FIG. 2A, the thickness of the polymer material sheet 14 is 0.4 mm, the length is 25 mm, and copper is formed on the end face of one side of the polymer material sheet 14 by vacuum deposition as about 150 nm. . You may spread about 10 nm of chromium as a copper base. For example, a glass sheet having a thickness of 0.4 mm and a length of 5 mm is used for the fixed end 13, and copper is similarly vacuum-deposited as an electrode 21 on one end face of the fixed end 13 (FIG. 2B). The fixed end 13 is firmly fixed to the colored layer 15 with the adhesive 17 on the entire surface as shown in FIG.

  On the other hand, only a part of the polymer material sheet 14 shown in FIG. 2A is adhered to the colored layer 15 and the adhesive 17 provided on the base material 11. At this time, the electrode 21 and the electrode 22 are in contact with each other as shown in FIG. Finally, as shown in FIG. 2D, packaging is performed with the exterior film 16. In order not to hinder the operation of the indicator 10, the upper surface of the indicator 10 including the polymer material sheet 14 is not provided with an adhesive portion with the exterior film 16, and for example, the bottom surface of the base material 11 is fixed as shown in FIG. A film 16 is further provided and adhered to the periphery of the indicator 10. The above is the manufacturing method.

  In addition, as an electrode manufacturing method, electroless plating or metal foil is considered without using a vacuum apparatus.

  Placing PLA pellets on a glass substrate placed on a 200 ° C hot plate, melting them, pressing another glass substrate from the pellets into a thin film, and then quenching them, the PLA film is polymerized A material sheet 14 was produced. The PLA film had a thickness of 0.4 mm and was cut into a size of 10 mm long × 25 mm wide. This was placed in an oven at 130 ° C., and the transmittance and shrinkage after 30 minutes, 60 minutes, and 90 minutes were measured. FIG. 3 shows the measurement result of the transmitted light intensity of this PLA film (polymer material sheet 14), and FIG. 4 shows the measurement result of the shrinkage rate of this PLA film (polymer material sheet 14). As shown in FIG. 3, the transmittance decreases substantially linearly with crystallization. It turned out to be very white due to light scattering. Further, the shrinkage rate in FIG. 4 also changed almost linearly, which was about 3% shorter than the initial length in 90 minutes. Therefore, how long 130 ° C. is applied can be read from the change in capacitance representing the degree of whitening and the change in the distance between the electrodes 21 and 22.

  FIG. 5 shows the isothermal crystallization process of LACEA H-100. The following data is published in Western Industrial Technology Center Research Report No. 50 (2007): 46, pages: 73-75.

  Pellets containing 2% of PLA with talc T2 (Katsumiyama Laboratories: SK-C) as a crystal nucleating agent in PLA are melted at 200 ° C., then rapidly cooled to a predetermined temperature and held at a certain temperature for 15 minutes. The thermal analysis was performed (isothermal crystallization process). With PLA alone, as indicated by I, no exothermic peak was observed in the isothermal process at 85 ° C., and no crystallization occurred. On the other hand, in the case where talc T2 is added as a nucleating agent to PLA, as shown by II, a peak of heat generation appears at a position of about 2 minutes, and it is considered that crystallization occurs. When compared with an isothermal process at a higher temperature of 105 ° C., a broad peak is observed in the vicinity of 11 minutes in PLA as indicated by III, and it is considered that crystallization occurs slowly. In addition, in PLA added with talc T2, a sharp peak is observed at 1 minute as shown by IV, and it can be seen that crystallization occurs rapidly.

  When PLA containing no additive is used, as shown by III in FIG. 5, crystallization starts about 4 minutes after heating at 105 ° C., and the crystallization rate becomes the fastest after 11 minutes. Thereafter, the crystallization rate continues to progress gradually while slowing down. Further, the transmittance of the sheet is expected to be whitened by crystallization and to have the same tendency as the time change shown in FIG. Therefore, it can be confirmed visually or using a chromaticity measuring device how many minutes 105 ° C. is applied from the transmittance. Furthermore, since the crystallization is accompanied by the heat shrinkage shown in FIG. 4, the distance between the electrode 21 and the electrode 22 gradually increases and the capacitance changes. Therefore, for example, if a configuration using PLA without additives as an indicator for confirming that 105 ° C. has been applied for 12 minutes is used, the transmittance after 12 minutes is higher than a predetermined transmittance, If it is larger than the predetermined value, it means that the temperature has not reached 105 ° C., or that the temperature has dropped in the middle.

  Further, as shown by IV in FIG. 5, when talc T2 is added, it rapidly crystallizes in 1 minute after application at 105 ° C. In this way, a material that whitens at a certain temperature cannot be used as a material that shows several tens of thermal history, but is suitable for use as a thermo label. Since the electrode 21 and the electrode 22 are disconnected by heat shrinkage, it can be easily confirmed whether or not the predetermined temperature is reached depending on the presence or absence of conduction.

  FIG. 6 shows a material in which 3 kinds of nucleating agents, talc T2, clay C2 (Katsumiyama Laboratory: T-clay), and mica M2 (Yamaguchi Mica Industry Co., Ltd .: A-11) are added to PLA at 2%. FIG. 6 is a graph plotting the time of an exothermic peak due to crystallization against various isothermal assumptions. Thus, the crystallization rate varies depending on the addition of the nucleating agent. PLA crystallizes at about 95-120 ° C., but the crystallization rate is the fastest, about 11 minutes.

  On the other hand, PLA added with a nucleating agent is as fast as, for example, about 1 to 7 minutes at 90 ° C., and crystallization is promoted by the addition of the nucleating agent. In addition, the addition of the nucleating agent expands the temperature range in which the crystallization peak appears, and crystallization is likely to occur at a lower temperature and a higher temperature than PLA alone. As described above, in order to obtain a desired crystallization characteristic, in addition to selecting and using a material, a desired crystallization temperature and crystallization speed can be obtained by adding a nucleating agent even for the same material.

  RFID is an abbreviation for Radio Frequency Identification, which is a general term for authentication (recognition) technology using radio waves. Recently, a combination of contactless communication using radio waves and authentication using IC chips is becoming the mainstream of RFID technology. Therefore, it is used to mean “RFID = contactless authentication technology using an IC chip”.

  RFID is used to perform object recognition, personal authentication, etc. by attaching an IC chip with an antenna processed into a tag or a label to a person or object and reading the information stored there with a device called a reader / writer. is there. One advantage of using RFID is that contactless authentication can be performed without touching a recognition object, and the other is that such contactless authentication can be performed simultaneously on multiple objects. This is a point of multiple simultaneous authentication. With these features, many business operations currently being performed by humans can be automated or simplified, enabling enormous cost savings, and preventing human error and systems. By improving the real-time nature of information, the quality of information is improved, and it is also expected to support accurate understanding of corporate resources and prompt decision making.

  The combination of the temperature sensor and the RFID is disclosed in Patent Document 1 and the like. Since the change of the indicator of the present invention can be read as a change in capacitance or a change in resistance, the article management can be performed smoothly by combining with the RFID. The RFID combined with the indicator of the present invention is preferably a passive tag that can be realized at low cost. A passive tag does not have a power source on the tag side, and uses a radio wave emitted from a reader / writer as power.

  Example 2 of the indicator of the present embodiment is a configuration in which the thermal time integration type indicator (TTI) 10 and the RFID of the embodiment of FIG. 1 are combined, and FIG. 7A is a configuration diagram, FIG. FIG. 7B shows a block diagram of an example of an RFID tag circuit. The configuration of the RFID refers to “a shelf label system with a temperature management function using a battery-less RFID tag” described in Japanese Patent Application Laid-Open No. 2007-111137.

  In FIG. 7A, the TTI 10 of this embodiment is connected to the RFID chip 31. The RFID chip 31 includes an RFID tag 33 that includes an antenna 32 for communication with a reader / writer. Here, the RFID chip 31 is shown in the block diagram of FIG.

  In FIG. 7B, an antenna 32 is connected to a tuning circuit 34 to perform radio communication with a reader / writer using electromagnetic waves, and is tuned to a carrier frequency to constitute a resonance circuit. At the subsequent stage of the tuning circuit 34, the voltage waveform of the induced electromotive force generated when the electromagnetic wave transmitted from the reader / writer antenna passes through the antenna 32 of the RFID tag is detected, and the induced electromotive force is detected as a half wave or a full wave. It is connected to a rectifier circuit 35 for rectifying and extracting a DC voltage.

Next, after the rectifier circuit 35, a clock generation circuit 36 for generating a system clock by dividing the detected carrier, a demodulation operation for extracting a signal from the carrier at the time of signal reception, and a signal transmission time A modulation / demodulation circuit 37 for modulation operation is connected by a switching element (not shown). Further, following the modulation / demodulation circuit 37, the control of the modulation / demodulation circuit 37, the unique ID information of the RFID chip 31 for the FRAM (Ferroelectric RAM: registered trademark of Ramtron, USA) 39, and the TTI 10 of the present embodiment A logic circuit 38 is connected to perform data writing or reading control of any one of the capacitance, resistance, voltage, and current signals detected in (1). In addition, an A / D converter (not shown) that converts any one of the capacitance, resistance, voltage, and current signals output from the TTI 10 of the present embodiment into an appropriate digital value, and the TTI 10 Is connected to the logic circuit 38 and the FRAM 39. The FRAM 39 is a ferroelectric nonvolatile memory, and data such as the unique ID information of the RFID chip 31 is not lost even when the circuit power is turned off. The frequency to be used varies depending on the communication distance and application, and a frequency band corresponding to the communication distance may be used.
Conventional TTI is a visual chemical indicator, and the indicator due to discoloration has low accuracy. The alternative is an electronic device that requires an electronic display for display, is expensive, large and requires a power source.

  On the other hand, the indicator of the present invention can be manufactured at an extremely low cost as compared with an electronic device. Further, by adopting the configuration of Example 2 in which the thermal time integration type indicator (TTI) of this embodiment is combined with RFID, it is directly visually confirmed by color change whether an object has been applied for a predetermined time at a predetermined temperature. Not only that, but the color change information can be taken out as an RFID output as it is, so it can be confirmed remotely, and the temperature history can be read by recording the TTI resistance change of this embodiment in the memory. Become.

  The indicator of the present invention is designed to change color at the sterilizable temperature and time in order to visually check whether the sterilizable temperature and time have been applied to the object to be sterilized in the high pressure steam sterilization of the medical device. It can be used as a heat time accumulation type indicator.

10 Thermal time integration type indicator (TTI)
DESCRIPTION OF SYMBOLS 11 Base material 13 Fixed end 14 Polymer material sheet 15 Colored layer 16 Exterior film 17 Adhesive 18 Window 21, 22 Electrode 31 RFID chip 32 Antenna 34 Tuning circuit 35 Rectifier circuit 36 Clock generation circuit 37 Modulation / demodulation circuit 38 Logic circuit 39 FRAM ( Ferroelectric RAM)
40 Interface circuit

Claims (2)

A substrate;
A first electrode and a second electrode formed opposite to each other above the substrate;
A polymer material sheet that is in contact with one or both of the first and second electrodes, and has a property of shrinking and becoming cloudy at a predetermined temperature;
An indicator comprising: means for identifying a color provided between the base material and the polymer material sheet.   2. The indicator according to claim 1, further comprising a reading unit that reads a distance between the first and second electrodes as a change in electrical variable.