KR20190067045A - Methods for fabricating flexible thermistor and thermal sensing device, and thermal sensing device including the flexible thermistor - Google Patents

Abstract

According to the present invention, a method for manufacturing a flexible thermistor comprises the steps of: preparing resistive ink by mixing polyethylene dioxyethylenethiophene (PEDOT)-polystyrene sulfonic acid (PSSA) with isopropyl alcohol or docusate; printing or coating the prepared resistive ink on a flexible substrate to form a resistance pattern; printing an electrode pattern in contact with the resistance pattern by using a conductive ink; drying the substrate having the resistance pattern and the electrode pattern formed thereon in a globe box over a predetermined time period to remove moisture; and encapsulating the resistance pattern and the electrode pattern. According to the present invention, the influence by humidity is minimized.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing a flexible thermal resistor, a method of manufacturing a temperature sensing device including a flexible thermal resistor, and a temperature sensing device including a flexible thermal resistor,

The present invention relates to a method of manufacturing a flexible thermal resistor, a method of manufacturing a temperature sensing device including a flexible thermal resistor, and a temperature sensing device including a flexible thermal resistor.

A thermal resistor is used to read the resistance value using a material having a different resistance characteristic depending on the temperature and accordingly to detect the temperature. Although these resistors vary in resistance with changes in temperature, they are very sensitive to humidity, making it difficult to measure the temperature stably due to the influence of humidity.

Particularly, in the normal temperature range of about 30 ° C to 40 ° C, the resistance material contained in the thermal resistor is less influenced by the humidity, but the thermal resistance can be measured stably at a temperature of less than 10 ° C There is a demand for. In particular, products requiring freshness require development of thermal resistors that can detect small temperature changes while operating at low temperatures.

The present invention provides a method for manufacturing a flexible thermal resistor that minimizes the influence of humidity by sealing the upper part of the resistance pattern formed by the resistive ink using the conductive polymer having stability in the atmosphere so as to minimize the resistance change due to moisture can do.

The present invention provides a manufacturing method of a temperature sensing device that can minimize the influence of moisture even by connecting external communication means by connecting a chip and a flexible thermal resistor that can communicate with the outside using an instant curing type conductive glue .

The present invention relates to a temperature sensing device which is formed on a flexible substrate and observes a change in resistance at a predetermined time interval in a state where the influence of moisture is minimized, .

A method of manufacturing a flexible thermal resistor according to an embodiment of the present invention includes the steps of: preparing a resistive ink by mixing polyethylene dioxyethylenethiophene (PEDOT) -polystyrene sulfonic acid (PSSA) with isopropyl alcohol or docusate; Printing a resistive ink on a flexible substrate to form a resistive pattern; printing an electrode pattern in contact with the resistive pattern using a conductive ink; Removing the moisture by drying over a predetermined time, and sealing the resistance pattern and the electrode pattern.

In one embodiment, the step of preparing the resistive ink may include mixing the PEDOT-PSSA and isopropyl alcohol in a volume ratio of 4: 1.

In one embodiment, the step of sealing the resistance pattern and the electrode pattern may include laminating with a polyethylene film.

In one embodiment, the step of sealing the resistance pattern and the electrode pattern includes coating a mixture of graphene oxide and polyvinylidene fluoride (PVDF) in dimethylformamide (DMF) . ≪ / RTI >

In one embodiment, the step of forming the resist pattern may include forming at least one of a roll-to-roll gravure, an offset, a gravure-offset, a reverse offset, a screen printing, a roll coating, a bar coating, And forming the resistance pattern using the resistive ink.

In one embodiment, the forming of the electrode pattern may include forming the electrode pattern with the conductive ink on the flexible substrate in at least one of roll-to-roll gravure, offset, gravure-offset, reverse offset, .

A method for manufacturing a temperature sensing device according to an embodiment of the present invention includes the steps of preparing a resistive ink by mixing polyethylene dioxyethylenethiophene (PEDOT) -polystyrene sulfonic acid (PSSA) with isopropyl alcohol or docusate, Printing the coated resistive ink on a flexible substrate to form a resistive pattern, printing an electrode pattern in contact with the resistive pattern using conductive ink, drying the printed circuit in the glovebox for a predetermined time or more Removing the moisture, sealing the resistance pattern and the electrode pattern to manufacture a thermal resistor, and connecting the short-range communication chip to the thermal resistor using a conductive glue.

In one embodiment, a method for fabricating a temperature sensing device according to an embodiment of the present invention includes dispersing nano-scale silver particles in hexane or toluene to prepare a conductive glue by adding a polyisocyanate as a binder .

In one embodiment, the method of fabricating a temperature sensing device according to an embodiment of the present invention may further include forming an antenna connected to the local area communication chip on the flexible substrate.

A temperature sensing apparatus according to an embodiment of the present invention includes a resistive ink prepared by mixing polyethylene dioxyethylenethiophene (PEDOT) -Polystyrenesulfonic acid (PSSA) with isopropyl alcohol or docusate, And a short-range communication chip electrically connected to the thermal resistor by using a conductive glue, and a short-circuiting chip electrically connected to the short-circuiting chip using the conductive glue. The short-range communication chip is configured to perform a step of receiving a resistance value of the thermal resistor at a predetermined time interval, and converting the resistance value received at the predetermined interval to a voltage and transmitting the voltage to the outside.

According to the embodiment, the temperature sensing device according to the present invention may include a cover layer for sealing the resist pattern and the electrode pattern of the thermal resistor after drying.

According to various embodiments of the present invention, resistive patterns are formed by printing or coating using resistive inks that have obtained wettability to flexible substrates that can be deformed in various forms, so that they have a uniform resistance value, A flexible thermal resistor can be provided. These thermal resistors are excellent in thermal sensing performance and can be transformed into various forms, so their application range is wide.

According to various embodiments of the present invention, a flexible thermal resistor can be provided that can minimize the effect of moisture on the thermal resistor through an additional sealing step to block moisture for the flexible thermal resistor.

According to various embodiments of the present invention, in connecting a chip capable of transmitting the measured value from the flexible thermal resistor to the outside, the conductive glue capable of minimizing the influence of moisture is connected, It is possible to provide a temperature sensing device capable of delivering the temperature.

1 is a flowchart illustrating a method of manufacturing a flexible thermal resistor according to an embodiment of the present invention.
Fig. 2 is a view for explaining a part of the configuration of the thermal resistor, and Fig. 3 is a diagram showing one embodiment of the thermal resistor.
4 is a graph showing a resistance value of a flexible thermal resistor according to an embodiment of the present invention.
5 is a graph showing resistance values of the flexible thermal resistor according to an exemplary embodiment of the present invention by repeatedly exposing the flexible thermal resistor to different temperature conditions.
6 is a view showing an embodiment of a temperature sensing device with a local communication chip attached to a flexible thermal resistor according to the present invention.
7 is a block diagram illustrating a temperature sensing apparatus according to an embodiment of the present invention.
8 is a diagram illustrating a thermal sensing system in which a temperature sensing device in accordance with an embodiment of the present invention communicates with an external mobile terminal.
FIGS. 9 and 10 show embodiments of screens output from the mobile terminal, which receives the temperature data sensed by the temperature sensing device via near-field communication.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to make the technical idea of the present invention clear. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram of a computer system according to an embodiment of the present invention; Fig. For convenience of explanation, the apparatus and method are described together when necessary.

1 is a flowchart illustrating a method of manufacturing a flexible thermal resistor according to an embodiment of the present invention.

Referring to FIG. 1, a resistive ink is prepared by mixing PEDOT-PSSA and isopropyl alcohol or docusate (step S110). According to the embodiment, the solution in which PEDOT-PSSA is dispersed may be a solution that has been commercialized. In order to print a solution in which PEDOT-PSSA is dispersed on a flexible substrate, it is necessary to match the wettability with the flexible substrate. In other words, it is important to ensure wettability in order to ensure a constant resistance after the resistive ink is printed. For this purpose, a resistive ink can be prepared by mixing a commercially available PEDOC-PSSA solution and isopropyl alcohol in a ratio of 4: 1, For example, a resistive ink can be prepared by mixing 80 wt% of PEDOT-PSSA solution and 10 wt% of isopropyl alcohol. According to an embodiment, a resistive ink may be prepared by mixing 1-5 wt% of PEDOT-PSSA solution and docusate (aerosol OT).

Specifically, adding DMSO or other organic solvent to the PEDOT-PSSA solution can lower the sheet resistance to several tens of ohms. However, considering the sensitivity, stability, and durability of the thermal resistor, if the resistance of the resistance component is too low, the current value may become high, which may not be suitable for the circuit configuration or the like. Therefore, in the present invention, isopropyl alcohol or docusate is mixed with PEDOT-PSSA to adjust the wettability so that the sheet resistance value of the resistance pattern to be formed below is formed to be about 1K? To 500K ?.

A resistance pattern is formed on the flexible substrate by printing or coating using the prepared resistive ink (step S120). According to an embodiment, a resistive pattern may be coated on a flexible substrate with a resistive ink in at least one of roll coating, bar coating and coma coating, or a roll-to-roll gravure, offset, gravure-offset, reverse offset, The resistance pattern may be printed using the resistive ink.

According to the embodiment, the resistance pattern to be coated or printed with the resistive ink may be a rectangular shape extending between the electrode patterns as shown in Fig. The sheet resistance of the resist pattern can be varied depending on the thickness of the resist pattern to be printed or coated on the flexible substrate, so that the present invention can adjust the sheet resistance by adjusting the thickness of the resistive ink coated or printed on the flexible substrate. For example, the thickness of the resist pattern formed on the flexible substrate may vary depending on the manner in which the resist pattern is coated or printed, or may differ depending on the wettability or the concentration of the resistive ink.

After the resist pattern is formed on the flexible substrate, the electrode pattern contacting with the resistance pattern can be printed using the conductive ink (step S130). The electrode pattern can be printed using a conductive ink. In the present invention, an electrode pattern can be printed on a flexible substrate using silver (Ag) ink having low resistance. Similar to the manner in which the resistive ink is printed, the electrode pattern can be formed by printing conductive ink on the flexible substrate in at least one of roll-to-roll gravure, offset, gravure-offset, reverse offset and screen printing. The electrode pattern can contact the resistive ink, i.e., the resistive pattern, and allow different currents to flow depending on the surface resistance of the resistive ink.

The thickness of the printed electrode pattern may be approximately 600 nm to 2 um. The average surface roughness of the electrode pattern printed in gravure using ink may be 1 nm to 5 nm, and the illuminance of the electrode pattern printed on a screen or the like may be several tens of nm.

According to the embodiment, the order in which the electrode pattern and the resistance pattern are formed may be different, and the electrode pattern and the resistance pattern may be formed substantially simultaneously. In another embodiment, the electrode pattern and the resistance pattern may be sequentially fabricated through a series of roll-to-roll printing processes.

The flexible substrate on which the resistance pattern and the electrode pattern are formed is dried in the glove box for a predetermined period of time (step S140). According to the embodiment, the water can be removed by baking in the glove box for 1 hour or more.

According to the embodiment, after the flexible substrate on which the resistance pattern and the electrode pattern are formed is placed in the glove box and the water is removed, the flexible substrate on which the resistance pattern and the electrode pattern are formed is dried for about 3 minutes at 125 ° C, It may also be fired in a box.

Removing the moisture remaining in the resistance pattern and the electrode pattern as described above can minimize the influence of moisture on the sheet resistance afterwards.

The dried resistance pattern and the electrode pattern are sealed (step S150), and the heat resistors are treated so as not to be affected by moisture even if they are exposed to moisture in the future. 3 is a view showing an embodiment of the resistance pattern and the electrode pattern which have undergone the sealing process.

According to the embodiment, the resist pattern and the electrode pattern are laminated with a PET (polyethylene terephthalate) film, or graphene oxide and PVDF (polyvinylidene fluoride) are mixed with DMF (dimethylformamide) It is possible to perform sealing by coating with one mixed liquid. For example, a flexible substrate on which a resistance pattern and an electrode pattern are formed can be passivated by mixing a mixture of 5 to 20% wt of graphene oxide and 5 to 20% wt of PVDF in 60 to 90% wt of DMF have.

Alternatively, depending on the embodiment, the resist pattern and the electrode pattern may be sealed using Novec EGC-1700 solution commercialized at 3M.

According to the manufacturing method of a flexible thermal resistor according to the present invention, it is possible to secure a stable sheet resistance value by coating or printing a resistance pattern using a resistive ink matching a wettability on a flexible substrate, In order to minimize the influence of moisture, firing is performed in the glove box to remove moisture and seal it in the future to block external moisture inflow. As a result, the temperature can be reliably and reliably sensed when exposed to varying temperatures without being affected by moisture.

Fig. 2 is a view for explaining a part of the configuration of the thermal resistor, and Fig. 3 is a diagram showing one embodiment of the thermal resistor.

Referring to FIG. 2, the flexible thermal resistor may include a resistance pattern RPTN and an electrode pattern EPTN. The resistance pattern RPTN can be coated or printed with a predetermined width Wa and a length La. In one embodiment, the resistance pattern RPTN may be formed to have a width of 1.2 cm and a length of 1 cm. According to the embodiment, the resistance pattern RPTN is formed with the pattern interval Wb between the electrode patterns EPTN, for example, the pattern interval Wb may correspond to 1 cm. Accordingly, the overlapping portions of the electrode patterns EPTN and the resistance pattern RPTN may correspond to 0.1 cm, respectively.

However, the shape of the resistance pattern and the electrode pattern shown in FIG. 2 is one embodiment. As shown in FIG. 3, the electrode pattern EPTN is formed in a jig jig shape while maintaining a constant gap between the two electrode patterns EPTN , And the resistance pattern RPTN is coated / printed between the electrode patterns EPTN. A cover layer CL for sealing the resistance pattern RPTN and the electrode pattern EPTN may be formed. As described above, the cover layer CL may be formed by laminating or coating.

4 is a graph showing a resistance value of a flexible thermal resistor according to an embodiment of the present invention.

Referring to FIG. 4, the resistance value increases from 32.3K? To 34.0K? While the temperature decreases from 20C to -12.5C over time. In particular, even after the temperature drops below zero, it is observed that the resistance value changes uniformly with temperature change.

5 is a graph showing resistance values of the flexible thermal resistor according to an exemplary embodiment of the present invention by repeatedly exposing the flexible thermal resistor to different temperature conditions. Referring to FIG. 5, Test 1 and Test 2 are obtained by decreasing and increasing the temperature, and Test 3 and Test 4 are similarly observed by decreasing and increasing the resistance. Looking at the measurement results, it can be seen that the hysteresis is stable within a certain range without difficulty in distinguishing the temperature.

 6 is a view showing an embodiment of a temperature sensing device with a local communication chip attached to a flexible thermal resistor according to the present invention. FIG. 6 is an actual photograph of a temperature sensing device manufactured according to an embodiment, and FIG. 7 is a block diagram illustrating a temperature sensing device.

6 and 7, the temperature sensing device 700 may include a flexible thermal resistor 711 and a short-range communication chip 713 coupled to a portion thereof. The temperature sensing apparatus 700 may further include a power supply unit 715 for supplying power to the flexible thermal resistor 711 and the short range communication chip 713. [

The temperature sensing device 700 capable of measuring the temperature by measuring the resistance using the flexible thermal resistor 711 must have a means for measuring the resistance value and reading the measured resistance value. Therefore, even if the flexible thermal resistor 711 itself blocks the inflow of water, there is a possibility that moisture may flow into the flexible thermal resistor 711 through the connection portion thereof while being connected with other components.

In order to solve the problem that moisture may flow into the connection portion of the flexible thermal resistor 711, the present invention uses a conductive glue (GLU) that cuts off water to connect the local communication chip 713 to the flexible thermal resistor 711 You can connect.

According to the embodiment, the conductive glue is cured within a short period of time, and when it is further dried, the hydrophobic polymer capable of preventing penetration of moisture with a small contact resistance can be cured to secure stability.

Conductive glue can be prepared by dispersing silver nanoparticles of 5 to 10 nm in size in 0.1 g of hexane or 5 ml of toluene and adding 0.01 to 0.05 g of a polyisocyanate as a binder.

When the conductive glue thus produced is further dried at 125 ° C, the contact resistance can be operated as a very stable connecting means because the contact resistance is about 1? To 10 ?, and the external moisture can be effectively blocked.

The local area communication chip 713 can transmit the resistance value of the flexible thermal resistor 711 to various external components through the local communication. For example, in a situation where a short distance communication technique using a mobile terminal is widely spreading, data based on the resistance value measured in the flexible thermal resistor 711 is supplied to the outside through the short distance communication chip 713, And can be provided as data for various decision making. In particular, in recent years, temperature-related data is stored according to the distribution and storage time of a food by attaching a short-distance communication-temperature sensor tag to a food package. When a consumer approaches a mobile terminal in a food package, And can be provided as a basis on which the consumer can confirm the temperature data and trust the freshness of the food.

Furthermore, the degree to which the freshness is guaranteed for a specific food may be calculated based on the time-temperature data. For example, based on temperature data received from a temperature sensing device attached to milk, it can be determined that milk has been stored continuously at temperatures below 4 ° C for 10 days after production. In this case, it is determined that the milk is still maintained fresh, so that the consumer can decide the purchase regardless of the expiration date. According to the embodiment, the criterion that the freshness can be maintained according to the kind of food may be changed. The freshness maintaining temperature state of each food is managed in a separate database and is presented to the user, or the freshness maintenance degree is calculated on the basis thereof, . The freshness check and calculation process may be performed in a mobile terminal or in a separate server.

In determining the freshness of the food according to the embodiment, the kind of the food, the time from the production time to the present time, the temperature, the time of exposure to the abnormal temperature, and the like can be taken into consideration and in particular, the bacteria information can be calculated and transmitted to the consumer . This calculation can be performed at the mobile terminal that receives the temperature data from the temperature sensing device 700 attached to the food package or the server that receives the temperature data from the mobile terminal.

In accordance with the embodiment, the local area communication chip 713 performs a communication function with an external mobile terminal and the like, and also receives the resistance value received by the flexible thermal resistor 711 at a predetermined time interval and converts it into a constant voltage value And means for storing sensed values for a predetermined time. According to an embodiment, the local area communication chip 713 may be implemented using a C programming language.

According to an embodiment, the temperature sensing device 700 may be provided with sensors, such as a flexible thermal resistor 711, for sensing temperature or sensing other external factors. In this case, the short range communication chip 713 can be operated by a simple platform type program so that various sensing values can be received and delivered to the outside.

The power supply unit 715 may include a battery BAT and the temperature sensing device 700 may include a rectifier circuit and an antenna ANT for receiving a radio signal from the outside and converting the received radio signal into a power source. The local communication chip 713 and the power supply unit 715 are formed on the flexible substrate 720. The local communication chip 713 and the power supply unit 715 are formed on the flexible substrate 720. However, .

8 is a diagram illustrating a thermal sensing system in which a temperature sensing device in accordance with an embodiment of the present invention communicates with an external mobile terminal.

Referring to FIG. 8, the mobile terminal 800 may receive temperature data sensed from the local communication chip 713 included in the temperature sensing device 700. The mobile terminal 800 may include a communication unit 810, a control unit 820, and a display unit 830. The mobile terminal 800 receives the temperature data through the communication unit 810 and converts it into a form that the controller 820 can identify by the user based on the temperature data changed by the received time and outputs the converted data through the display unit 830 can do.

FIGS. 9 and 10 show embodiments of screens output from the mobile terminal, which receives the temperature data sensed by the temperature sensing device via near-field communication.

Referring to FIGS. 9 and 10, the temperature sensed per unit time is displayed, and these temperatures can be confirmed during the time interval, so that the temperature sensing device can identify the temperature change of the attached product at a glance.

In one embodiment, the control unit 820 of the mobile terminal 800 receives data transmitted from an external local communication chip using an Android stew program, for example, voltage, temperature, pH, or other physicochemical elements May be implemented.

Accordingly, the mobile terminal 810 can receive the data provided from various sensing devices including the temperature sensing device 700, understand what the data mean and deliver it to the user.

As described above, according to various embodiments of the present invention, a method of manufacturing a flexible thermal resistor can provide a flexible thermal resistor that can stably detect a temperature change while minimizing the influence of moisture. Flexible thermal resistors can be manufactured through mass-production printing / coating processes using low-cost resistive inks and conductive inks, thus reducing manufacturing costs and enabling mass production.

Further, since the flexible thermal resistor manufactured according to the present invention is connected to a flexible printed circuit board through a conductive glue that can prevent moisture penetration even when connected to a silicon communication technology based short range communication chip, Accordingly, even if the thermal resistor and the communication chip are not simultaneously formed on the silicon-based chip, the function as the temperature tag can be sufficiently performed, so that the manufacturing cost of the temperature sensor tag can be drastically reduced.

Claims (11)

Preparing a resistive ink by mixing polyethylene dioxyethylenethiophene (PEDOT) -polystyrene sulfonic acid (PSSA) with isopropyl alcohol or docusate;
Printing or coating the resistive ink on a flexible substrate to form a resistance pattern;
Printing an electrode pattern in contact with the resistance pattern using conductive ink;
Drying the substrate on which the resist pattern and the electrode pattern are formed in the glove box over a predetermined period of time to remove moisture; And
And sealing the resistance pattern and the electrode pattern. The method according to claim 1,
Wherein the step of preparing the resistive ink comprises:
And mixing said PEDOT-PSSA and isopropyl alcohol in a 4: 1 volume ratio. The method according to claim 1,
Wherein the step of sealing the resistance pattern and the electrode pattern comprises:
Lt; RTI ID = 0.0 > laminated < / RTI > with a polyethylene film. The method according to claim 1,
Wherein the step of sealing the resistance pattern and the electrode pattern comprises:
Coating a mixture of graphene oxide and polyvinylidene fluoride (PVDF) in a mixed solvent of dimethylformamide (DMF). The method according to claim 1,
The step of forming the resistance pattern may include:
Forming the resistive pattern on the flexible substrate using the resistive ink in at least one of roll-to-roll gravure, offset, gravure-offset, reverse offset, screen printing, roll coating, bar coating, / RTI > 6. The method of claim 5,
The step of forming the electrode pattern
Wherein the electrode pattern is formed on the flexible substrate with the conductive ink in at least one of a roll-to-roll gravure, an offset, a gravure-offset, a reverse offset, and a screen printing method. Preparing a resistive ink by mixing polyethylene dioxyethylenethiophene (PEDOT) -polystyrene sulfonic acid (PSSA) with isopropyl alcohol or docusate; And
Printing or coating the resistive ink on a flexible substrate to form a resistance pattern;
Printing an electrode pattern in contact with the resistance pattern using conductive ink;
Drying the printed circuit in the glove box over a predetermined period of time to remove moisture;
Sealing the resistance pattern and the electrode pattern to manufacture a thermal resistor;
And connecting the short-range communication chip to the thermal resistor using conductive glue. 8. The method of claim 7,
Further comprising dispersing nanoscale silver particles in hexane or toluene and adding a polyisocyanate as a binder to prepare the conductive glue. 8. The method of claim 7,
Further comprising the step of forming an antenna connected to said local area communication chip on said flexible substrate. A resistance pattern formed by printing or coating a resistive ink prepared by mixing polyethylene dioxyethylenethiophene (PEDOT) -polystyrene sulfonic acid (PSSA) with isopropyl alcohol or docusate on a flexible substrate, A thermal resistor manufactured by printing an electrode pattern in contact with the resistance pattern; And
And a short-range communication chip electrically connected to the thermal resistor using a conductive glue,
The short-
Receiving a resistance value of the thermal resistor at a predetermined time interval, and converting the resistance value received at the predetermined interval to a voltage and transmitting the voltage to the outside. 11. The method of claim 10,
And a cover layer that covers the resist pattern and the electrode pattern of the thermal resistor after being dried.

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