Patent Description:
Generally, a sensor of the related art is provided in the form of a terminal to measure salinity and a sugar content and determine a denaturalization level of edible oil and fat.

A terminal type sensor has advantages in that measurement and output of a measured result may be performed without a separate device, but should be provided with a separate power supply, whereby a problem occurs in that volume, weight, etc. are increased.

Particularly, with the trend of increasing users who necessarily use a mobile terminal such as a smartphone, it is considered to replace some functions of a sensor with those of a power supply unit and an output unit of a smartphone.

Therefore, a portable sensor is required, which performs only a measurement function of a material and transmits the measured result to an external device or receives a sensing signal.

However, for such a portable sensor, it is necessary to consider a material and structure for obtaining an exact measured value while satisfying a small size.

In a portable sensor for implementing the material and structure, it is general that a vacuum deposition method is used to form a conductive area such as a sensing electrode. The vacuum deposition method may cause deformation of a substrate due to a process condition of a high temperature and cause increase of the manufacturing cost.

Therefore, a sensor manufactured by a printing method may be considered to substitute for the vacuum deposition method. Moreover, it is required to solve a corrosion problem and a reliability problem such as durability degradation, which may occur in the sensor of the printing method.

<CIT> relates to a radio frequency identification device, for detecting at least one volatile substance, comprising an integrated circuit, an antenna electrically connected to said integrated circuit, and at least one conductor, between said integrated circuit and said antenna, preferably said at least one conductor comprises a conducting composite, preferably said conducting composite comprises a polymer matrix and a conductor.

MOLINA-LOPEZ F ET AL: "All additive inkjet printed humidity sensors on plastic substrate".

An object of the present invention is to solve the aforementioned problems of a sensor, in the form of a terminal, not being compact and the problem of high manufacturing costs and low manufacturing quality of a sensor manufactured using a deposition method in order to replace such a sensor with a sensor manufactured by a printing method,.

Another object of the present invention is to provide a sensor by solving a corrosion problem of a sensing electrode, a durability problem, etc. that may occur in a sensor of a printing method.

The objects of the present invention are solved by the features of the independent claim.

To achieve the above problems or other problems, there is provided a sensor as defined in claim <NUM>.

Also, according to a preferred embodiment, there is provided a sensor characterized in that the conductive particles of the coating electrode further include a Graphite and a carbon black.

Also, according to a preferred embodiment, there is provided a sensor characterized in that the graphite and the carbon black are configured at <NUM>% or less of a total mass of the coating electrode.

Also, according to a preferred embodiment, there is provided a sensor characterized in that the binder includes one of a Polyethylene oxide (PEO) based resin, an Oleic acid based resin, an Acrylate based resin, an Acetate based resin, and an Epoxy based resin.

Also, according to a preferred embodiment, there is provided a sensor characterized in that the conductive particles are configured by combination of a flake shape or a spherical shape.

Also, according to a preferred embodiment, there is provided a sensor characterized in that the antenna pattern, the circuit line and the sensing electrode are made of the same material, provided on the same layer, and the coating electrode is provided by being deposited on the sensing electrode.

Also, according to a preferred embodiment, there is provided a sensor characterized in that a minimum distance between the two coating electrodes is <NUM>, and a thickness of the coating electrode from an upper end of the sensing electrode is <NUM>.

Also, according to a preferred embodiment, there is provided a sensor characterized in that the sensing electrodes are spaced apart from each other, by <NUM> or more and <NUM> or less.

Also, according to a preferred embodiment, there is provided a sensor characterized in that the antenna pattern, the sensing electrode and the circuit line have a thickness of <NUM> or more and <NUM> or less.

Also, according to a preferred embodiment, there is provided a sensor characterized in that the substrate includes any one of polyethylene erephthalate (PET), polyimide (PI), polystyrene (PS) and polyethylene naphthalate (PEN).

Also, according to a preferred embodiment, there is provided a sensor characterized in that the antenna pattern has a width of <NUM> or more and <NUM> or less, and an adjacent distance of the antenna pattern is <NUM> or more and <NUM> or less.

Also, according to a preferred embodiment, there is provided a sensor further comprising a passivation layer forming an opening, which exposes at least one area of the sensing electrode, having a surface energy greater than that of the substrate.

Also, according to a preferred embodiment, there is provided a sensor further comprising a protective layer deposited on the substrate, protecting the conductive layer and the passivation layer.

Advantageous effects of a sensor according to the present invention are as follows.

According to at least one of the embodiments of the present invention, a compact sensor linked to an external device may be provided.

According to at least one of the embodiments of the present invention, a sensor is capable of being manufactured at a low temperature to reduce the probability of occurrence of a defect rate caused by deformation.

According to at least one of the embodiments of the present invention, a sensor is capable of being manufactured by minimum layers for several conductive components to reduce the manufacturing cost.

According to at least one of the embodiments of the present invention, a sensor is capable of being manufactured at a low cost through an electronic printing method.

Further scope of applicability of the present application will become more apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from the detailed description.

Any "aspect", "example" and "embodiment" of the description not falling within the scope of the claims does not form part of the invention and is provided for illustrative purposes only. <FIG> is a front view illustrating a sensor <NUM> according to one embodiment of the present invention, and.

<FIG> is an exploded perspective view illustrating a sensor <NUM> of <FIG>. For convenience of description, description will be given with reference to <FIG> and <FIG> together.

The sensor comprises a substrate <NUM>, a conductive layer <NUM>, and an insulating layer. In this case, the conductive layer <NUM> includes an antenna pattern <NUM>, a sensing electrode <NUM>, and a circuit line <NUM>.

The substrate <NUM> configures a non-conductive layer. The substrate <NUM> serves as a target in which the conductive layer <NUM> is packaged. For example, the substrate <NUM> may include a plastic layer <NUM> and a silica layer <NUM>.

The plastic layer <NUM> is made of plastic (polymer compound or synthetic resin) having flexibility. The plastic may include at least one selected from a group of a polyethylene erephthalate (PET), a polyimide (PI), a polystyrene (PS) and a polyethylene naphthalate (PEN). The silica layer <NUM> may be coated on one surface of the plastic layer <NUM>. The silica layer <NUM> may be formed between the plastic layer <NUM> and the conductive layer <NUM>. The silica layer <NUM> enables fast diffusion of a sensing target material <NUM>, especially solution, stability of the sensing target material <NUM>, and attachment intensity enhancement of the conductive layer <NUM>. The silica layer <NUM> may have a thickness of several nm to several tens of nm.

The conductive layer <NUM> is provided on one surface of the substrate <NUM>.

The conductive layer <NUM> includes an antenna pattern <NUM>, a circuit line <NUM> and a sensing electrode, as described above.

The sensing electrode <NUM> causes an impedance change by a contact of the sensing target material <NUM>. The impedance change may mean a state of the sensing target material <NUM>.

Details of the sensing electrode <NUM> will be described later.

The antenna pattern <NUM> transmits or receives a radio signal to or from an external device. For example, the antenna pattern <NUM> may serve to receive a sensing command signal of the external device to measure an impedance change of the sensing target material <NUM> or transmit the measured impedance change value to the external device.

The circuit line <NUM> forms a passage for signal transfer by electrically connecting the antenna pattern <NUM> with the sensing electrode <NUM>.

The conductive layer <NUM> may be formed in a single body. The case that the antenna pattern <NUM>, the sensing electrode <NUM> and the circuit line <NUM> of the conductive layer <NUM> are formed in a single body may mean that they are functionally identified from one another but may structurally be formed of the same material by the same process in view of the manufacturing process. However, as the case may be, the coating electrode <NUM> of the conductive layer <NUM> may be formed of a hetero-material unlike the other components or implemented by a process different from that of the other components. A detailed description of the coating electrode will be described later.

Alternatively, if necessary, the components of the conductive layer <NUM> may be formed respectively by a separate process without being formed in a single body.

The conductive layer <NUM> provided in a single body may not be detachable physically.

The conductive layer <NUM> may be formed on the substrate <NUM> by an electron printing method.

The conductive layer <NUM> of the related art is formed by a vacuum deposition method. The conductive layer <NUM> formed by the vacuum deposition method is advantageous in that it has a stable structure but the manufacturing and material costs are increased in that addition process such as etching is required after vacuum deposition, and a shape deformation of the substrate <NUM> may be caused by the process performed at a high temperature.

The electronic printing process of the conductive layer <NUM> may be performed by any one method of Gravure offset, Gravure printing, and Screen printing.

At least some of the conductive layer <NUM> may be formed as the same layers. The case that at least some of the conductive layer <NUM> are formed of the same material as the same layers may mean that the conductive layer <NUM> is printed on the substrate <NUM> by a printing process of one time in view of the manufacturing process. If the conductive layer <NUM> is printed by a printing process of one time, the manufacturing process may be simplified, whereby the manufacturing cost and time may be minimized.

In detail, an area of the conductive layer <NUM> formed as the same layer may include all or some of the antenna pattern <NUM>, and the circuit line <NUM> and the sensing electrode <NUM>. A detailed description of the conductive layer <NUM> will be given later.

The antenna pattern <NUM> transmits or receives a signal to or from an external device.

The external device may mean an electronic device having a communication function. For example, examples of the external device include a smartphone, a computer, a digital broadcasting terminal, a PDA, etc..

The antenna pattern <NUM> generates a direct current power source by receiving a radio signal from the external device, wherein the generated direct current power source is used for measurement driving of the sensor <NUM>. A measured impedance difference of the sensing target material <NUM> may again be transmitted to the external device through the antenna pattern <NUM>.

Since the direct current power source is generated by the antenna pattern <NUM>, the sensor <NUM> may not be provided with a separate power supply unit. This may result in a compact size of the sensor <NUM> and minimize the manufacturing cost.

The antenna pattern <NUM> may be formed on one surface of the substrate <NUM> two-dimensionally. Particularly, the antenna pattern <NUM> may be provided along outer corners of the substrate <NUM> to make sure of an antenna length, and may be provided in a screw shape by being wound several times in accordance with a necessary length. A shape and pattern of the antenna pattern <NUM> may be change in various ways to implement an antenna function.

The antenna pattern <NUM> may have a line width of <NUM> to <NUM> to have high inductance. An interval of the antenna pattern <NUM>, which is wound several times, with an adjacent line may be of <NUM> to <NUM> to make sure of an appropriate capacitance component.

The antenna pattern <NUM> may include a pattern area for performing an original function of an antenna, and a connection area for electrically connecting the pattern area with the circuit line <NUM> or the sensing electrode <NUM>. The pattern area and the connection area may be provided on the same layer, but may be provided on their respective layers different from each other to actively perform electrical connection with the other components. To this end, an insulating area may additionally be provided to avoid an unintended electrical connection between different layers. A detailed description of the insulating area will be given later.

The antenna pattern <NUM> may operate as a radiator of an NFC(Near Field Communication) antenna. Information exchange of the NFC antenna may be performed using communication options of <NUM>.

The circuit line <NUM> electrically connects the antenna pattern <NUM> with the sensing electrode <NUM>. Also, the circuit line <NUM> may electrically be connected with a device <NUM> for controlling the sensor <NUM>. That is, the circuit line <NUM> may mean all areas except the antenna pattern <NUM> and the sensing electrode <NUM> of the conductive layer <NUM>.

A passivation layer <NUM> prevents the sensing target material <NUM> from leaking to the substrate <NUM> area. Therefore, the sensor <NUM> is prevented from operating in error due to the sensing target material <NUM> flowing to the circuit line <NUM>. Also, the passivation layer <NUM> may have a certain height to prevent the sensing target material from moving. The passivation layer <NUM> may collect the sensing target material <NUM> in the sensing electrode <NUM>.

The passivation layer <NUM> has a surface energy greater than that of the substrate <NUM> to allow the sensing target material <NUM> to form liquid crystals in the passivation layer <NUM>, whereby the sensing target material <NUM> may not be diffused toward the substrate <NUM>.

The passivation layer <NUM> may include a first opening 131a for exposing at least a portion of the sensing electrode <NUM>. Only a partial area exposed through the first opening 131a may be used as the sensing electrode <NUM>.

The sensing electrode <NUM> has a total length A of <NUM> to <NUM>, and may be exposed at a length of <NUM> to <NUM> through the first opening 131a. As the case may be, the total length of the sensing electrode <NUM> may be equal to the length of the sensing electrode <NUM> exposed through the first opening 131a, or the sensing electrode <NUM> may partially be exposed through the first opening 131a.

The length of the sensing electrode <NUM> exposed through the first opening 131a affects resolution of the sensor <NUM>, printing reproducibility according to mass production and reliability of the sensor <NUM>. The shorter the length of the sensing electrode <NUM> exposed through the first opening 131a is, the more improved resolution of the sensor <NUM> may be.

A width B of the sensing electrode <NUM> may be provided within the range of <NUM> to <NUM>. The narrower the width B of the sensing electrode <NUM> is, the more improved resolution of the sensor <NUM> may be. However, a too narrow width of the sensing electrode <NUM> may cause an unstable printing process of the conductive layer <NUM>. Preferably, the width B of the sensing electrode <NUM> is <NUM> to <NUM> for a stable printing process.

Supposing that both poles of the sensing electrode <NUM> are a first sensing electrode 122a and a second sensing electrode 122b, an interval C between the first sensing electrode 122a and the second electrode 122b may be provided within the range of <NUM> to <NUM>.

However, if the interval C between the first sensing electrode 122a and the second electrode 122b is too wide and the amount of the sensing target material is not enough, it may be difficult to perform exact measurement. That is, the sensing target material should be in contact with the first sensing electrode 122a and the second sensing electrode 122b by forming a liquid drop. Considering this, the interval C between the first sensing electrode 122a and the second electrode 122b is preferably provided within the range of <NUM> to <NUM>.

A height D of the sensing electrode <NUM> may be <NUM> to <NUM>. The height D of the sensing electrode <NUM> may affect a thickness of the sensor <NUM> and durability and reliability of the sensing electrode <NUM>. If the height D of the sensing electrode <NUM> is lower than <NUM>, a problem may occur in that the sensing electrode <NUM> is lost in accordance with repetition of sensing. Due to a limitation of the printing process and to prevent the thickness of the sensor <NUM> from being increased, it is preferable that the height of the sensing electrode <NUM> is lower than <NUM>.

An antenna insulating layer <NUM> and an antenna bridge <NUM> form a structure for connecting the antenna pattern <NUM> with the circuit line <NUM>. If the antenna pattern <NUM> is formed in a screw shape by being wound in the substrate <NUM>, one end of the antenna pattern <NUM> should be extended toward a direction where the other end of the antenna pattern <NUM> is provided. The antenna bridge <NUM> forms this extended area, and the antenna insulating layer <NUM> may be provided between the antenna bridge <NUM> and the antenna pattern <NUM> such that the antenna bridge <NUM> is not interfered with the antenna pattern <NUM> printed through the existing printing process.

A protective layer <NUM> may be formed of an insulating material and arranged to face one surface of the substrate <NUM> so as to cover the substrate <NUM> and all of components packaged in the substrate <NUM>, such as the conductive layer <NUM> and the passivation layer <NUM>, thereby electrically and physically protecting the corresponding components. However, the protective layer <NUM> may include a second opening 160a for exposing the first opening 131a of the passivation layer <NUM>.

A device <NUM> may be packaged in the substrate <NUM> and thus electrically connected with the circuit line <NUM>.

Various electronic components related to operation of the sensor <NUM> may be implemented by the device <NUM>. The electronic components, for example, may include a power generator, a controller, a converter, and a communication unit.

The radio signal received through the antenna pattern <NUM> is transferred to the device <NUM> through the circuit line <NUM>. The device <NUM> may generate an alternating current power source through the direct current power source supplied thereto and input the generated alternating current power source to the sensing electrode <NUM>.

<FIG> is a cross-sectional view illustrating an area A-A' of <FIG>, and <FIG> is a partially enlarged view illustrating an area A-A' of <FIG>. For convenience of description, description will be given with reference to <FIG> and <FIG> together.

The sensing electrode <NUM> is direction in contact with the sensing target material <NUM>, and if the sensing electrode <NUM> is formed by a vacuum deposition method, it is sufficient that the area of the sensing electrode <NUM> is only made of a material such as Pt or Au. However, as described above, if the antenna pattern and the circuit line are configured as the same layer through the electronic printing method, a material cost is too increased.

This problem may be solved by replacing the sensing electrode <NUM> with Ag.

That is, Ag is provided as main component of the sensing electrode <NUM>.

The sensing electrode <NUM> is made of a combined component of conductive particles <NUM> of Ag and a binder <NUM> of a resin. The conductive particles <NUM> may have a spherical shape or a flake shape. The flake shaped conductive particles <NUM> may have conductivity relatively higher than that of the spherical shaped conductive particles.

The conductive particles <NUM> may have a size of several tens of nm to <NUM> to make sure of a reaction specific surface area. The sensing electrode <NUM> causes an impedance change by reaction with the sensing target material <NUM>, and a capacitance component and a resistance component exist in the impedance. If the reaction specific surface area of the conductive particles <NUM> is widened, oxidation or corrosion of the sensing electrode by reaction may be suppressed, and lifespan of the sensor <NUM> may be extended.

The binder <NUM> supports the conductive particles <NUM>. The binder <NUM> may serve to improve durability and reliability of the sensing electrode <NUM>.

The resin binder <NUM> selected from a Polyethylene oxide (PEO) based group, an Oleic acid based group, an Acrylate based group, an Acetate based group and an Epoxy based group.

The sensing electrode <NUM> has pores <NUM>. The pores <NUM> may have a size of several nm to several tens of µm. If the sensing electrode <NUM> has pores <NUM>, since the sensor <NUM> is not damaged easily by repeated mechanical deformation, reliability of the sensor <NUM> may be improved.

The sensing electrode <NUM> may form an acute angle with the substrate <NUM>. That is, a corner area of the sensing electrode <NUM> forms a slow inclination from the substrate <NUM> so that the sensing electrode <NUM> is not easily separated from by bending of the substrate <NUM>.

However, if the sensing electrode <NUM> is exposed to be in contact with the sensing target material <NUM>, a standard reduction potential of a material such as Ag may be lowered, whereby it is likely that the sensing electrode <NUM> is corroded. Corrosion of the sensing electrode <NUM> disturbs a contact between the sensing target material <NUM> and the sensing electrode <NUM> and causes occurrence of noise in impedance measurement.

Also, a surface area of the sensing electrode <NUM> which is in contact with the sensing target material <NUM> is reduced due to sizes of the particles of the sensing electrode <NUM>. This reduction of the contact surface area also acts to cause reduce exactness of sensing.

Three types of embodiments for improving conductivity and reliability and durability of conductive sensing due to the configuration of the sensing electrode <NUM> will be described later.

The coating electrode <NUM> is provided outside the sensing electrode <NUM>.

The coating electrode <NUM> is provided on an outer side of the sensing electrode <NUM> through the electronic printing method such that the sensing electrode <NUM> may be treated with sensitization.

The possibility of occurrence of noise in an impedance change sensed by the sensing electrode <NUM> is reduced due to the coating electrode <NUM>. That is, the coating electrode <NUM> serves to increase electric conductivity of the sensing target material <NUM> and the sensing electrode <NUM>.

Moreover, the coating electrode <NUM> may enhance durability and wear resistance of the sensing electrode <NUM>.

The coating electrode <NUM> may be provided to be similar to the sensing electrode <NUM>. That is, the coating electrode <NUM> is provided by combination of conductive particles <NUM> and a binder <NUM>.

The conductive particles <NUM> of the coating electrode <NUM> include a carbon nano tube (CNT).

The binder <NUM> of the coating electrode <NUM> may minimize a gap <NUM> by connecting the conductive particles <NUM> of the coating electrode <NUM>. The binder of the coating electrode <NUM> is made of resin which may include at least one selected from Polyethylene oxide (PEO) based group, Oleic acid based group, Acrylate based group, Acetate based group and Epoxy based group.

However, if the conductive particles <NUM> of the coating electrode <NUM> are made of a carbon nano tube only, since resistance is high, sensing resolution is degraded. Therefore, the conductive particles <NUM> of the coating electrode <NUM> may additionally include Graphite. Graphite serves to enhance conductivity of the sensing electrode <NUM>.

Also, the conductive particles <NUM> of the coating electrode <NUM> may include a carbon black. The carbon black serves to enhance durability or wear resistance of the sensing electrode <NUM>.

The Graphite and the carbon black may be configured at <NUM>% or more of a total mass of a conductive material.

The carbon nano tube, the graphite and the carbon black of the conductive particles <NUM> perform the above functions by being organically associated with one another without performing each function independently.

The coating electrode <NUM> is provided to cover the outer side of the sensing electrode <NUM>. Pores <NUM> of the sensing electrode <NUM> serve to have durability for mechanical deformation of the sensor <NUM> as described above. On the contrary, the pores <NUM> disturbs exact impedance measurement by lowering conductivity of the sensing electrode <NUM>. The coating electrode <NUM> allows the sensing electrode <NUM> filled with the pores <NUM> to have high conductivity, whereby exact impedance can be measured.

As described above, the sensing electrode <NUM> has two electrodes 122a and 122b spaced apart from each other to be in contact with the sensing target material <NUM>. This case is equally applied to the coating electrode <NUM>.

The first coating electrode 123a and the second coating electrode 123b of the coating electrode <NUM> may be spaced apart from each other at an interval of <NUM>. This value corresponds to an approximate value, and the interval does not require <NUM>, exactly.

The thickness of the coating electrode, that is, the thickness from the uppermost end of the sensing electrode <NUM> to the uppermost end of the coating electrode <NUM> may be <NUM> or less.

The aforementioned passivation layer <NUM> may be provided outside the coating electrode <NUM>. That is, the sensing electrode <NUM>, the coating electrode <NUM> and the passivation layer <NUM> may sequentially be deposited at the outside from the substrate <NUM>. Therefore, a length condition of the coating electrode <NUM> may be applied equally to the length condition of the sensing electrode <NUM>. Therefore, the coating electrode <NUM> may be exposed to the outside through the first opening 131a as much as the length of the sensing electrode <NUM>.

Unlike the aforementioned coating electrode, a conjugate polymer layer may be used to improve conductivity of the sensing electrode <NUM>. The conjugate polymer layer may include a material such as a conductive polymer (PEDOT:PSS/P3HT). The conjugate polymer layer may be implemented in the sensing electrode <NUM> by a patterning process, or may be removed after being absorbed in the sensing electrode <NUM> for a certain time in a state that it is coated on a front surface.

To improve conductivity of the sensing electrode <NUM> and maintain measurement reliability, the sensing electrode <NUM> may be pressed through a rolling process. In a state that the sensing electrode <NUM> is printed, a certain temperature may be increased, and in a state that the increased temperature is maintained, the sensing electrode <NUM> may be pressed through a roller.

However, if the sensing electrode <NUM> is pressed through the rolling process, coupling of the sensing electrode <NUM> may be broken by pressure. To minimize this phenomenon, a groove may be formed in the roller and then the rolling process may be performed.

<FIG> is a view illustrating a sensor <NUM> of the present invention, which is linked to an external device <NUM>.

Hereinafter, a description will be given based on the sensor type of the embodiment <NUM> unless mentioned separately. However, the description may equally be applied to the examples <NUM> and <NUM> within the range that does not depart from contradiction.

A description will be given based on that the external device <NUM> is a mobile terminal, especially smartphone although the external device <NUM> may have various types.

The sensor <NUM> transmits or receives a radio signal to or from an external device through an antenna pattern <NUM>.

The sensor <NUM> generates a direct current power source through a power generator <NUM> to drive a circuit unit <NUM>. In this way, the sensor <NUM> of the present invention does not have a component for power supply but generates a direct current power source by using the radio signal received from the external device <NUM>. A controller <NUM>, a converter <NUM>, a communication unit <NUM> and a sensing electrode <NUM> are operated by the generated direct current power source.

The controller <NUM> is driven by the direct current power source which is supplied. The controller <NUM> generates an alternating current voltage and inputs the generated alternating current voltage to the sensing electrode <NUM>. Based on the case of the embodiment <NUM>, the sensing electrode <NUM> may refer to a concept that includes a coating electrode <NUM> (see <FIG>). The sensing electrode <NUM> which will be described later may include a coating electrode.

If the sensing electrode <NUM> is reacted with a sensing target material, the sensing electrode <NUM> causes an impedance change. The impedance change of the sensing electrode <NUM> is represented by a change of the alternating current voltage generated by the controller <NUM>. The sensing target material may be identified in accordance with a range of an output value.

The change of the alternating current voltage may be changed to a digital signal. The converter <NUM> converts the change of the alternating current voltage represented based on the impedance change of the sensing electrode <NUM> to a digital signal. The communication unit <NUM> transmits the digitalized signal to the external device <NUM> through the antenna pattern. In this case, the communication unit <NUM> may be NFC Tag IC.

The external device <NUM> generates information by receiving the digitalized signal from the sensor <NUM> and stores and manages the generated information.

The external device <NUM> may display information through a display.

<FIG> is a conceptual view illustrating a structure of a circuit line <NUM>, a sensing electrode <NUM>, a coating electrode <NUM> and a passivation layer <NUM>.

The sensor is formed by printing, heat drying and hardening processes. Particularly, if the printing process is repeated, a process error, especially alignment error may occur, and an error may occur due to contradiction of the substrate even during the heat drying process.

Resolution of the sensor may be determined in accordance with an exposed length of first and second sensing electrodes 322a and 322b. A total length and the exposed length of the first and second sensing electrodes 322a and 322b are <NUM>,<NUM> or less which is very short, whereby the process error is likely to be generated. Therefore, a structure for minimizing the process error is required.

The first sensing electrode 322a, the second electrode 322b, the first coating electrode 323a, the second coating electrode 323b, the circuit line <NUM> and the passivation layer <NUM> may be formed by the printing process. The passivation layer <NUM> is arranged to cover the first sensing electrode 322a, the second sensing electrode 322b, the first coating electrode 323a, the second coating electrode 323b and the circuit line <NUM>. Therefore, the passivation layer <NUM> is formed after printing of the sensing electrodes 322a and 322b, the coating electrodes 323a and 323b and the circuit line <NUM>. Therefore, the process error may occur due to repetition of the printing process and during the heat drying process. For this reason, the sensing electrodes 322a and 322b or the coating electrodes 323a and 323b may be exposed or covered unlike a design intention.

The sensing electrodes 322a and 322b and the coating electrodes 323a and 323b may be partitioned into three parts along a longitudinal direction. These three parts are defined as first end portions 322a1, 322b1, 323a1 and 323b1, second end portions 322a2, 322b2, 323a2 and 323b2, and center portions 322a3, 322b3, 323a3 and 323b3. The passivation layer <NUM> covers the first end portions 322a1, 322b1, 323a1 and 323b1 and the second end portions 322a2, 322b2, 323a2 and 323b2, and the first opening 331a exposes the center portions 322a3, 322b3, 323a3 and 323b3.

The sensing electrode <NUM> and the coating electrode <NUM> are formed to be longer than the length of the first opening 331a. The first opening 331a may control the exposed length of the sensing electrode <NUM> and the coating electrode <NUM>. Therefore, a length G of the first opening 331a of the passivation layer <NUM> may be controlled accurately to lower an error.

It is preferable that a width H of the first opening 331a is wider than an interval between the first electrodes 322a and 323a and the second electrodes 322b and 323b of the sensing electrode <NUM> or the coating electrode <NUM> and does not exceed <NUM>. If the width H of the first opening 331a is too wide, a sensing target material, which will be in contact with the sensing electrode <NUM> or the coating electrode <NUM>, may be diffused without forming a liquid drop.

Referring to an experimental result, the shorter the length of the sensing electrode <NUM> or the coating electrode <NUM> exposed through the first opening <NUM> is, the narrower the width of the sensing electrode <NUM> or the coating electrode <NUM> is, and the wider the interval between the two electrodes is, the more improved resolution is. However, if the sensing electrode <NUM> and the coating electrode <NUM> are designed only for the purpose of improving resolution, a problem of durability and reliability may occur. Therefore, considering resolution, durability and reliability, the structure of the sensing electrode <NUM> and the coating electrode <NUM> should be designed.

<FIG> and <FIG> are flow charts illustrating a manufacturing method for a sensor related to the present invention.

Referring to <FIG>, the conductive layer is printed on the substrate through the printing process (S100). The conductive layer includes an antenna pattern, a sensing electrode, a coating electrode and a circuit line.

If the antenna pattern, the sensing electrode and the circuit line are made of the same material, the antenna pattern, the sensing electrode and the circuit line of the conductive layer may be formed simultaneously by a printing process of one time (S110). Therefore, this may reduce material and manufacturing costs. This will be defined as a first printing process for convenience. The antenna pattern, the sensing electrode and the circuit line may be provided on the same layer due to the first printing process.

Afterwards, the coating electrode may be printed on the outer side of the sensing electrode (S120). Since the coating electrode is made of a material different from that of the sensing electrode, the coating electrode may be formed through additional second printing process.

Therefore, the coating electrode configures a hetero-layer deposited on a layer provided with the sensing electrode.

The printing process of the conductive layer uses a powdered ink or paste. A composition of the powdered ink or paste may include conductive particles of 40weight% to 70weight%, and an organic material of 30weight% to 60weight% containing solvent. As a result, oxidation and corrosion of the sensing electrode or the coating electrode may be minimized.

As described above, the conductive particles of the sensing electrode are made of Ag. Meanwhile, the conductive particles of the coating electrode made of carbon nano tube.

The conductive particles of the sensing electrode or the conductive particles of the coating electrode may have a spherical shape or a flake shape.

A solvent for mixing the conductive particles with the binder may include at least one selected from a group of Acetone, Allyl alcohol, Acetic acid, Acetol, Methyalcohol and Benzene.

The printing process of the conductive layer <NUM> may be any one of Screen, offset, and Gravure.

After the printing process, the conductive layer may be hardened through heat drying (S200). Heat drying may be performed at <NUM> to <NUM>. The aforementioned solvent may be evaporated during heat drying. To enable the process of a low temperature of <NUM> or less, it is preferable that the conductive particles have a size of several tens of nm to <NUM> in the form of powder.

Particularly, heat drying may be performed after a first printing process for printing the sensing electrode and a second printing process for printing the coating electrode. As the coating electrode is printed on the sensing electrode prior to heat drying, the coating electrode enters a portion between gaps of the sensing electrode, whereby the sensing electrode and the coating electrode may be coupled to each other more densely. If the sensing electrode and the coating electrode are coupled to each other densely, conductivity is enhanced, and the coating electrode may be prevented from being easily separated from the substrate or the sensing electrode by a high coupling force.

Alternatively, as shown in <FIG>, after the first printing process of the sensing electrode, the heat drying process may be performed primarily and then the second printing process may be performed for the coating electrode.

After the heat drying process is completed for both the first printing process and the second printing process, the passivation layer and the antenna insulating layer may be printed (S300).

The passivation layer and the antenna insulating layer may be made of the same material, and therefore may be formed at the same time through one printing process. That is, the passivation layer and the antenna insulating layer may form the same layer on the conductive layer.

The printed passivation layer and antenna insulating layer may be hardened (S400). The passivation layer and the antenna insulating layer may be hardened by ultraviolet (UV) rays.

The printing processes may be performed multiple times to make sure of sure insulation reliability (S500). At this time, the antenna insulating layer which is first printed may be defined as a first antenna insulating layer, and the antenna insulating layer which is printed later may be defined as a second antenna insulating layer. After the second antenna insulating layer is printed, the second antenna insulating layer may be further hardened in the same manner as the hardening process of the first antenna insulating layer (S600).

If necessary, in addition to the first antenna insulating layer and the second antenna insulating layer, additional antenna insulating layer may be printed. In this case, the same hardening process as that of the first antenna insulating layer or the second antenna insulating layer is performed.

An antenna bridge is printed on the antenna insulating layer (S700). The antenna bridge may be made of the same material as that of the conductive layer.

The antenna bridge may be heat-dried in the same manner as the conductive layer (S800). Details of a heat drying condition are the same as those described in the heat drying process of the conductive layer.

Next, the device may be bonded to the substrate (S900). The device is electrically connected with the circuit line.

Afterwards, the protective layer may be covered on the substrate to protect the components packaged in the substrate (S1000).

<FIG> are graphs illustrating that ADC change according to measurement times for each of a sensor of the related art and a sensor of the present invention is measured.

As shown, it is noted that an ADC value according to measurement times is uniformly maintained without change when Nacl and food are sequentially measured through the sensor of the present invention unlike the sensor of the related art. Therefore, it is noted that a resultant value of high reliability can be obtained by the user of the sensor without the problem of corrosion or durability.

It will be apparent to those skilled in the art that the present specification can be embodied in other specific forms.

The above embodiments are therefore to be construed in all aspects as illustrative and not restrictive. The scope of the specification is determined by the appended claims.

Claim 1:
A sensor (<NUM>) comprising:
a non-conductive substrate (<NUM>); and
a conductive layer (<NUM>) electronically printed on one surface of the substrate (<NUM>),
wherein the conductive layer (<NUM>) includes:
an antenna pattern (<NUM>) for transmitting or receiving a radio signal to or from an external device;
a sensing electrode (<NUM>) connected to the antenna pattern (<NUM>) through a circuit line (<NUM>), wherein the sensing electrode includes two sensing electrodes (122a, 122b) spaced apart from each other for sensing an impedance change between the two sensing electrodes (122a, 122b) due to a contact of a sensing target material with the two sensing electrodes (122a, 122b); and
a coating electrode (<NUM>) deposited on the sensing electrode (<NUM>), wherein the coating electrode (<NUM>) includes two coating electrodes (123a, 123b), which respectively cover the spaced two sensing electrodes (122a, 122b) for removing an occurrence of noise of the impedance change by increasing electric conductivity of the sensing electrode (<NUM>),
wherein the sensing electrode (<NUM>) includes:
a plurality of conductive particles (<NUM>);
a binder (<NUM>) made of resin and supporting the conductive particles (<NUM>); and
a plurality of pores (<NUM>) serving to have durability for mechanical deformation of the sensor (<NUM>),
wherein the coating electrode (<NUM>) includes:
a plurality of conductive particles (<NUM>);
a binder (<NUM>) made of resin and supporting the conductive particles (<NUM>); and
a plurality of gaps (<NUM>) between the plurality of conductive particles (<NUM>), and
wherein the coating electrode (<NUM>) covers an outer side of the sensing electrode (<NUM>) and fills the pores (<NUM>) of the sensing electrode (<NUM>),
wherein the conductive particles (<NUM>) of the sensing electrode (<NUM>) include Ag, and the conductive particles (<NUM>) of the coating electrode (<NUM>) include a carbon nano tube (CNT).