Ultraflexible upright corbino structure and four-terminal electrode-configured organic electrochemical transistor

Abstract

The present invention relates to an OECT applied to a skin-attachable biosignal sensor, and may include a flexible substrate layer, a lower electrode layer including a source electrode and a drain electrode formed on the flexible substrate layer, a channel portion having a cobino structure including a cylindrical opening formed between the lower electrode layers, an active layer formed along the inner wall of the channel portion, and an upper electrode layer including a gate electrode formed on the upper part of the active layer. Additionally, the OECT may include a 4-terminal electrode configuration including a first terminal and a second terminal for applying current, and a third terminal and a fourth terminal for detecting voltage. According to the present invention, the third and fourth terminals detect the potential of the active layer when no current flows, thereby eliminating potential drop caused by parasitic resistance that may occur during the measurement process. In addition, since the active layer is formed vertically along the inner wall of the cylindrical opening in the channel portion of the Cobino structure, the continuity of the channel structure can be maintained even under deformation conditions of the flexible substrate. Accordingly, the OECT according to the present invention can be utilized to stably measure bioelectrical signals such as electrocardiogram (ECG), electromyogram (EMG), and ocular potential (EOG) under high sensitivity and low power conditions while attached to the skin.

Description

Technology Field

[0001] The present invention relates to organic electrochemical transistor (OECT) technology, and in particular to a 4-terminal vertical cobino structure OECT capable of fundamentally suppressing parasitic resistance on an ultra-flexible thin film substrate and enabling high sensitivity and low power operation, and a skin-attachable biosignal sensing device using the same. Background Technology

[0002] OECT is useful for measuring signals such as electrocardiograms (ECG), electromyograms (EMG), and electroocular potentials (EOG) by electrically converting biosignals. However, conventional OECTs have the following technical limitations.

[0003] 1. Actual transconductance (g) due to parasitic series resistance (line resistance and contact resistance) m ) Increase is limited.

[0004] 2. In a planar structure, reducing the channel length drastically lowers mechanical deformation durability.

[0005] 3. g through a wide Wd / L ratio m Even if amplification is attempted, effective gate voltage loss occurs due to the influence of the voltage drop (IR-drop) within the board.

[0006] 4. Operation is unstable and motion artifacts increase in the skin-interface environment.

[0007] The present invention explains that by applying a 4-terminal vertical Covino structure, parasitic resistance is eliminated, and mechanical stability for ultra-flexible skin adaptation and ultra-low power operation are achieved. The problem to be solved

[0008] The present invention aims to solve the aforementioned problem and other related problems.

[0009] In addition, one exemplary objective of this specification is to provide an improvement in the performance of a biosignal sensor attachable to the skin.

[0010] More specifically, this invention aims to resolve signal distortion caused by parasitic resistance (line resistance and contact resistance) in existing OECT-based biosignal sensors, power consumption issues resulting from increased driving voltage, and reduced mechanical stability in environments with skin deformation.

[0011] The technical problem that the OECT including the ultra-flexible vertical Cobino structure and 4-terminal electrode according to the technical concept of the technology disclosed in this specification aims to solve is not limited to the problem of solving the problems mentioned above, and other problems not mentioned will be clearly understood by a person skilled in the art from the description below. means of solving the problem

[0012] An OECT according to one embodiment of the present invention for achieving the above objective may include a vertical cobino channel structure formed on an ultra-flexible substrate and connecting an upper electrode and a lower electrode. Here, the through hole of the connecting portion may be configured in a spherical shape.

[0013] In addition, the OECT may include a 4-terminal electrode configuration comprising a first terminal and a second terminal for applying current, and a third terminal and a fourth terminal for detecting voltage.

[0014] Here, the third and fourth terminals may be configured so that no current flows through them and may be used as terminals for detecting only voltage signals.

[0015] Meanwhile, the channel portion of the above-mentioned Covino structure may include a cylindrical opening (via), and an active layer for OECT may be formed along the inner wall of the opening.

[0016] In addition, the active layer of the above OECT may comprise poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS) or a p-type organic conductive polymer material equivalent thereto.

[0017] The above OECT can be manufactured integrally with a flexible substrate so that the entire substrate can respond to bending and stretching deformations.

[0018] An embodiment of the technology disclosed in this specification is not limited to the configurations mentioned above, and should be understood to include various modifications that can be made by a person skilled in the art within the scope of the art or the description and drawings below. An Organic Electrochemical Transistor (OECT) for signal detection according to an embodiment of the technology disclosed in this specification comprises a flexible substrate layer, a lower electrode layer including a source electrode and a drain electrode formed on the flexible substrate layer, a channel portion of a cobino structure formed between the lower electrode layers and including a cylindrical opening and a p-type conductive polymer-based active layer formed along the inner wall of the opening, an upper electrode layer including a gate electrode formed on the upper part of the active layer, and a 4-terminal electrode configuration including a first terminal and a second terminal connected to the source electrode and the drain electrode, and a third terminal and a fourth terminal connected to the active layer but detecting potential in a state where no current flows, wherein the third terminal and the fourth terminal detect a change in potential of the active layer and exclude a potential drop due to parasitic resistance.

[0019] In addition, the flexible substrate layer may include at least one of parylene, polyimide, thermoplastic polyurethane, or a flexible insulating material similar thereto.

[0020] In addition, the thickness of the flexible substrate layer may be in the range of 0.3 μm to 10 μm.

[0021] In addition, the active layer may include PEDOT:PSS or a p-type conductive polymer material.

[0022] In addition, the active layer may be formed by including at least one of spin coating, inkjet printing, spray coating, or electrochemical polymerization processes.

[0023] In addition, the above-mentioned cylindrical opening may be formed by including at least one of photolithography, laser processing, or plasma etching processes.

[0024] In addition, the source electrode and drain electrode may include at least one of gold, silver, platinum, carbon-based conductive ink, or graphene electrode material.

[0025] In addition, the upper electrode layer may include an Ag / AgCl electrode or a conductor material for an electrolytic gate.

[0026] In addition, the above OECT may further include a protective film layer to improve stability against external moisture and friction.

[0027] A bioelectric signal sensor according to one embodiment of the technology disclosed in this specification comprises any one of the aforementioned OECTs and further comprises a skin adhesive layer or a hydrogel interface layer so as to be attached to the skin.

[0028] A wearable bio-monitoring system according to one embodiment of the technology disclosed in this specification includes the aforementioned bioelectrical signal sensor and further includes a signal amplifier and a data analysis unit that process the signal obtained from the sensor.

[0029] A biosignal measurement method according to one embodiment of the technology disclosed in this specification measures at least one biosignal among an electrocardiogram (ECG), an electromyogram (EMG), or an ocular potential (EOG) using the aforementioned bioelectrical signal sensor. Effects of the invention

[0030] According to one embodiment of the present invention, an OECT including a 4-terminal electrode configuration has the effect of substantially eliminating the influence of line resistance and contact resistance that may occur during the measurement process by separating the current application terminal and the voltage sensing terminal.

[0031] Accordingly, the potential applied to the channel of the OECT is accurately maintained, allowing the inherent electrical characteristics of the device to be precisely expressed.

[0032] In addition, the above OECT includes a vertically oriented cobino structure, which allows for efficient adjustment of the geometric ratio to the channel length and channel width, thereby having the effect of significantly improving the signal amplification capability (gm) of the device.

[0033] Meanwhile, since the above OECT is formed on an ultra-flexible substrate, it has the effect of being able to operate stably even under various mechanical deformation situations occurring in the skin environment, such as bending, stretching, and wrinkle formation.

[0034] In addition, since the above OECT can be directly attached to the skin to detect minute biosignals such as electrocardiogram (ECG), electromyogram (EMG), and electroocular potential (EOG) under low-power conditions, it has the effect of being applicable as a portable, wearable, or long-term monitoring device.

[0035] However, the effects described in this specification are not limited to the embodiments described above, and should be interpreted to include other effects that a person skilled in the art can easily understand from the description in this specification. Brief explanation of the drawing

[0036] A brief description of each drawing is provided to help to better understand the drawings cited in this specification. FIG. 1 is a perspective view illustrating the overall structure of an OECT according to one embodiment of the present invention. The figure illustrates the shapes of a source electrode, a drain electrode, an active layer, and a cobino channel portion formed on an ultra-flexible substrate. FIG. 2 is an equivalent circuit diagram of an OECT including a 4-terminal electrode configuration according to an embodiment of the present invention. The figure illustrates the principle in which the current application terminal and the voltage sensing terminal are separated to eliminate IR voltage drop caused by parasitic resistance. FIG. 3 is a photograph of an OECT on an ultra-flexible substrate according to one embodiment of the present invention. FIG. 4 is a graph showing the results of a comparison of total resistance between a 2-terminal measurement method and a 4-terminal measurement method according to one embodiment of the present invention. Figure 5 is a photograph showing how the external shape of an OECT according to one embodiment of the present invention changes with changes in tensile strain. FIG. 6 is a scanning electron microscope (SEM) image confirming that the surface of the active layer of an OECT according to one embodiment of the present invention is deformed into a wrinkled shape under tensile deformation conditions. FIG. 7 shows an OECT according to an embodiment of the present invention g under repetitive elongation and compression deformation conditions. m This is a graph illustrating the characteristics that are maintained. Figure 8 is the result of measuring an electrocardiogram (ECG) signal by attaching an OECT according to one embodiment of the present invention to the skin. Figure 9 is the result of measuring an electromyogram (EMG) signal by attaching an OECT according to one embodiment of the present invention to the skin. Figure 10 is the result of measuring an electroocular potential (EOG) signal by attaching an OECT according to one embodiment of the present invention to the skin. Specific details for implementing the invention

[0037] The technology disclosed in this specification is subject to various modifications and may have various embodiments. Specific embodiments are illustrated in the drawings and described in detail in the detailed description. Identical or similar components are given the same reference numerals regardless of the drawing symbols, and redundant descriptions thereof are omitted. However, this is not intended to limit the technology disclosed in this specification to specific embodiments, and it should be understood that the technology disclosed in this specification includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the technology disclosed in this specification.

[0038] In describing the technology disclosed in this specification, if it is determined that a detailed description of related prior art could unnecessarily obscure the essence of the technology disclosed in this specification, such detailed description is omitted. Additionally, numbers used in the description of this specification (e.g., 1st, 2nd, etc.) are merely identification symbols to distinguish one component from another.

[0039] In addition, when a component is described in this specification as being "connected" or "connected" to another component, it should be understood that the component may be directly connected to or directly connected to the other component, but unless otherwise specifically stated, it may also be connected or connected through another component in between. On the other hand, when a component is described as being "directly connected" to or "directly connected" to another component, it should be understood that no other component exists in between.

[0040] In addition, components expressed as '~part' in this specification may consist of two or more components combined into a single component, or a single component may be divided into two or more components according to more detailed functions. Furthermore, each component described below may additionally perform some or all of the functions performed by other components in addition to the primary function it is responsible for, and it goes without saying that some of the primary functions performed by each component may be exclusively performed by other components.

[0041] Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0042] In this application, terms such as “comprising” or “having” are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0043] Although the present disclosure has been illustrated and described in detail in the drawings and above description, it should be understood that the present disclosure is illustrative rather than limiting in nature, and that only certain embodiments have been shown and described, and that all variations and modifications falling within the spirit of the present disclosure are preferably protected.

[0044] Hereinafter, embodiments based on the technical concept of the technology disclosed in this specification will be described in detail in turn.

[0045] Referring to FIG. 1, an OECT according to one embodiment of the present invention may include a flexible substrate layer (110), a lower electrode layer (120) having a source electrode and a drain electrode formed therein, a channel portion (130) having a cobino structure including a cylindrical opening, an upper electrode layer (140), and a protective film layer (150).

[0046] In addition, the OECT may have a 4-terminal electrode configuration including a first terminal and a second terminal for applying current, and a third terminal and a fourth terminal for detecting voltage.

[0047] First, the substrate layer (110) can be formed from a flexible insulator. The substrate material may be parylene, polyimide, or a flexible polymer material, and may be formed by deposition, spin coating, or lamination processes.

[0048] Referring to FIGS. 2 and 3, the channel portion (130) of the Covino structure includes a cylindrical opening (via), and the active layer (131) is formed along the inner wall of the opening.

[0049] The above active layer may include PEDOT:PSS or a p-type conductive polymer material and may be formed by a spin coating, spray coating, or ink printing process.

[0050] Referring to FIG. 4, the 4-terminal electrode configuration separates the current path and the voltage measurement path, thereby minimizing the potential drop caused by parasitic line resistance or contact resistance during measurement.

[0051] Referring to FIG. 5, the OECT of the present invention is formed on an ultra-flexible substrate and can respond to deformation even in mechanical deformation environments such as bending, wrinkle formation, or tensile deformation.

[0052] Referring to FIGS. 6 and 7, the surface of the active layer of the OECT is deformed into a wrinkled structure under conditions of increased tensile strain or repeated stretching and compression, and the structural continuity of the device can be maintained even under such mechanical deformation.

[0053] Referring to FIGS. 8, 9, and 10, an OECT according to one embodiment of the present invention can be directly attached to the skin and can be applied as a sensor that detects bioelectrical signals such as electrocardiogram (ECG), electromyogram (EMG), and ocular potential (EOG) under low power conditions.

[0054] The description above presents the best mode of the technology disclosed herein and provides examples to explain the technology disclosed herein and to enable those skilled in the art to manufacture and use the technology disclosed herein. The specification as written is not intended to limit the technology disclosed herein to the specific terms presented.

[0055] Accordingly, although the technology disclosed in this specification has been described in detail with reference to the examples above, those skilled in the art may make modifications, changes, and variations to these examples without departing from the scope of the technology disclosed in this specification.

Claims

Claim 1 An Organic Electrochemical Transistor (OECT) for skin-attachable biosignal detection comprises: a flexible substrate layer; a lower electrode layer including a source electrode and a drain electrode formed on the flexible substrate layer; a channel portion having a cobino structure formed between the lower electrode layers and including a cylindrical opening, and including a p-type conductive polymer-based active layer formed along the inner wall of the opening; an upper electrode layer including a gate electrode formed on the upper part of the active layer; and a 4-terminal electrode configuration including a first terminal and a second terminal connected to the source electrode and the drain electrode, and a third terminal and a fourth terminal connected to the active layer but detecting potential in a state where no current flows, wherein the third terminal and the fourth terminal detect a change in potential of the active layer to exclude a potential drop caused by parasitic resistance. Claim 2 In claim 1, the flexible substrate layer comprises at least one of parylene, polyimide, thermoplastic polyurethane, or a flexible insulating material similar to these, in an OECT. Claim 3 In claim 1, the OECT wherein the thickness of the flexible substrate layer is in the range of 0.3 μm to 10 μm. Claim 4 In claim 1, the active layer comprises an OECT comprising PEDOT:PSS or a p-type conductive polymer material. Claim 5 In claim 1, the active layer is formed by at least one of spin coating, inkjet printing, spray coating, or electrochemical polymerization processes. Claim 6 In claim 1, the cylindrical opening is formed by including at least one of photolithography, laser processing, or plasma etching process. Claim 7 In claim 1, the source electrode and drain electrode comprise at least one of gold, silver, platinum, carbon-based conductive ink, or graphene electrode material. Claim 8 In claim 1, the upper electrode layer comprises an Ag / AgCl electrode or a conductor material for an electrolytic gate, in an OECT. Claim 9 In claim 1, the OECT further comprises a protective film layer to improve stability against external moisture and friction. Claim 10 A bioelectric signal sensor comprising an OECT according to any one of claims 1 to 9, and further comprising a skin adhesive layer or a hydrogel interface layer, so as to be attachable to the skin. Claim 11 A wearable bio-monitoring system comprising a bioelectrical signal sensor according to claim 10, and further comprising a signal amplifier and a data analysis unit for processing signals obtained from said sensor. Claim 12 A biosignal measurement method comprising measuring at least one biosignal among an electrocardiogram (ECG), an electromyogram (EMG), or an electroocular potential (EOG) using a bioelectrical signal sensor according to claim 10.

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