Highly Durable n-Type Organic Mixed Ionic-Electronic Conductor Material and High-Performance OECT Device Using the Same

Abstract

The present invention discloses a sterilizable n-type organic electrochemical transistor and a skin-attachable biosignal monitoring device utilizing the same, characterized by comprising: an active layer composed of an n-type organic mixed ion-electron conductor stable to ultraviolet rays, moisture, and heat; two electrode portions in direct contact with the active layer; and a separating layer that separates the two electrode portions from each other.

Description

Technology Field

[0001] The present invention relates to a skin-attachable biosignal monitoring device, and more specifically, to a sterilizable n-type organic mixed ion-electron conductor, a high-performance OECT device utilizing the same, and a skin-attachable biosignal monitoring device utilizing the same. Background Technology

[0002] With the recent advancements in wearable electronic devices and biosensors, the demand for skin-attached electronic devices capable of stably monitoring the human body's biological signals for extended periods is rapidly increasing. Among these, organic electrochemical transistors feature low-voltage operation and high transconductance (g m It is attracting attention as a sensor platform for measuring signals such as electrocardiogram (ECG), electromyogram (EMG), and electroencephalogram (EEG) due to advantages such as biocompatibility. However, most existing OECT technologies are developed based on p-type organic semiconductors (PEDOT:PSS), which limits signal amplification in the positive potential region and has the problem that it is difficult to accurately detect positive and negative biosignals simultaneously due to unbalanced transconductance between the positive and negative regions.

[0003] In addition, n-type organic semiconductors generally have low oxidation stability and are sensitive to moisture and oxygen, which leads to performance degradation and oxidative deterioration during long-term operation. They also have limitations in terms of low physical and chemical stability during sterilization (autoclave, UV) processes or in high-humidity environments.

[0004] As a result, it has been very difficult to implement an n-type OECT that is stable for a long time and sterile in actual clinical or skin-attached environments. Therefore, there is a need to develop an n-type OECT structure that simultaneously ensures high electrical performance, excellent environmental resistance, sterile stability, and skin adhesion. The problem to be solved

[0005] The present invention aims to solve the aforementioned problem and other related problems.

[0006] Conventional p-type organic mixed ion-electron conductor-based organic electrochemical transistors exhibit high transconductance only in the negative potential region, making it difficult to amplify positive potential signals. Consequently, they have the limitation of being difficult to precisely measure biological signals where positive and negative potentials coexist, such as ECGs and EMGs.

[0007] Meanwhile, n-type organic mixed ion-electron conductors are sensitive to oxygen and moisture, leading to easy oxidative degradation, and possess chemical instability that makes it difficult to operate stably for extended periods in humid or aqueous environments. Furthermore, while sterilization treatments such as UV irradiation or autoclaving are essential for medical use, conventional organic semiconductors lack sterilization resistance, as they undergo degradation, discoloration, and reduced conductivity during these processes. In addition, they fail to adequately cope with mechanical deformation caused by the curvature and stretching of the skin, resulting in increased contact resistance and signal noise, which poses a problem in that it is difficult to measure biosignals stably for a long time.

[0008] In addition, one exemplary objective of this specification is to provide a skin-attachable electronic device through the development of a sterilizable and flexible n-type organic electrochemical transistor.

[0009] The technical problem to be solved by the n-type organic electrochemical transistor according to the technical concept of the technology disclosed in this specification is not limited to the problem of solving the problems mentioned above, and other unmentioned problems will be clearly understood by a person skilled in the art from the description below. means of solving the problem

[0010] A sterilizable n-type organic electrochemical transistor according to one embodiment of the present invention for achieving the above objective may include: an active layer composed of an n-type organic mixed ion-electron conductor stable to ultraviolet rays, moisture, and heat; two electrode portions in direct contact with the active layer; and a separating layer that separates the two electrode portions from each other.

[0011] Here, the two electrode portions may exist in a planar or vertical form and may exist in a structure that is electrically connected through the active layer.

[0012] In addition, the separation layer can be placed between two electrodes to block a direct electrical connection between the two electrodes.

[0013] Meanwhile, the active layer is stably maintained without deformation caused by externally applied oxygen, moisture, and heat, and thus can maintain its performance by sterilizing through ultraviolet rays and high-temperature heat treatment.

[0014] In addition, the active layer can amplify signals even in the positive potential region as an n-type semiconductor material.

[0015] An organic electrochemical transistor according to one embodiment of the technology disclosed herein comprises an n-type mixed ion-electron conductor (OMIEC) capable of stable electrochemical doping / dedoping even in oxygen and moisture environments, wherein the conductor comprises poly(benzodifurandione) (PBDF), and the change in charge mobility and electrical conductivity of the conductor is maintained at ±10% or less even under UV irradiation and high humidity environments.

[0016] In addition, the n-type mixed ion-electron conductor has a LUMO level of -4.9 eV or lower than the oxygen reduction potential, ensuring oxidation stability, and can perform reversible electrochemical oxidation-reduction reactions in an environment of 0.1 M NaCl or PBS aqueous solution.

[0017] In addition, the organic electrochemical transistor includes a vertical channel structure formed by interposing an insulating layer between the upper and lower electrodes, and by additionally providing two voltage sensing terminals (Vsense1, Vsense2) to eliminate line resistance, the transconductance (gm) can be 300 mS or more.

[0018] In addition, the organic electrochemical transistor may have a rate of change of current and transconductance (gm) of 10% or less even after irradiation with ultraviolet light (UV, wavelength 256–365 nm) and sterilization in an autoclave (121°C, 1.2 atm, 20 min).

[0019] In addition, the organic electrochemical transistor is formed on a Parylene-C / SU-8 composite layer substrate having a thickness of 3 μm or less, so that the rate of change of current can be maintained at ±10% or less even under tensile deformation of 200% or more or repeated bending deformation of 1000 times or more.

[0020] In addition, the organic electrochemical transistor operates at a driving voltage of 0.01 V or less and can detect biological signals (ECG, EMG, EEG, etc.) under 10 mV conditions.

[0021] In addition, the product of transconductance and volume capacitance (μC*) of the transistor is 1500 F·cm¹·V¹·s¹ or greater, and the performance can be maintained for 8 hours or more even in a high humidity environment with a relative humidity of 85% or higher.

[0022] A skin-attached biosignal monitoring device according to one embodiment of the technology disclosed in this specification includes any one of the aforementioned organic electrochemical transistors, and the organic electrochemical transistor stably detects an ECG signal with a contact impedance of 10 kΩ or less and a signal-to-noise ratio (SNR) of 35 dB or more when in contact with the skin. Effects of the invention

[0023] According to one embodiment of the present invention, as a stable n-type organic mixed ion-electron conductor without deformation against oxygen, moisture, and heat, it has the advantage of enabling the development of a safe skin-attachable electronic device through sterilization. In particular, it is electrically stable due to a low lowest unoccupied molecular orbital (LUMO) level and has high transconductance, allowing for high amplification even at low driving voltages, thereby enabling precise detection of minute biopotential changes.

[0024] In addition, there is almost no change in current and transconductance and minimal change in surface roughness even after UV and autoclave sterilization, making it suitable for use as a reusable sensor for medical and clinical applications. Furthermore, it maintains long-term performance even in high-humidity environments, exhibiting significantly improved resistance to moisture and oxidation compared to conventional n-type organic electrochemical transistors. Moreover, it shows very little performance degradation even under repeated mechanical deformation, and its ultra-thin structure adheres closely to the skin surface, minimizing contact impedance and signal noise.

[0025] However, the effects according to one embodiment of the technology disclosed in this specification are not limited to those mentioned above, and other effects not mentioned will be clearly understood by a person skilled in the art from the description below. Brief explanation of the drawing

[0026] A brief description of each drawing is provided to help to better understand the drawings cited in this specification. FIG. 1 is a cross-sectional view of an n-type organic mixed ion-electron conductor structure and an organic electrochemical transistor device according to an embodiment of the present invention. Figure 2 is a graph showing the energy levels of an n-type organic mixed ion-electron conductor according to an embodiment of the present invention in vacuum, moisture, and saline moisture environments. Figure 3 shows the measurement results of moisture stability of organic electrochemical transistor devices according to the embodiments and comparative examples of the present invention. Figure 4 is the result of measuring long-term stability in a moist environment through repeated measurements according to an embodiment of the present invention. Figure 5 shows the results of measuring the stability of an organic electrochemical transistor before and after sterilization according to an example. Figure 6 is the result of the elasticity analysis of an organic electrochemical transistor according to an example. Figure 7 is the result of an analysis of device performance stability according to repeated stretching of an organic electrochemical transistor according to an embodiment. FIG. 8 is a circuit diagram of a skin-attachable biosignal monitoring device utilizing an organic electrochemical transistor according to an embodiment. Figure 9 shows a photograph of a skin-attached biosignal monitoring device utilizing an organic electrochemical transistor according to an embodiment and the biosignal measurement results. Specific details for implementing the invention

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] A singular expression includes a plural expression unless the context clearly indicates otherwise.

[0032] 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.

[0033] 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.

[0034] Hereinafter, preferred embodiments will be described in detail with reference to the attached drawings.

[0035] Figure 1 is a cross-sectional view of the molecular structure of PBDF, a conventional n-type organic mixed ion-electron conductor, and an organic electrochemical transistor device.

[0036] Referring to Figure 1, the structure can be seen to include an active layer composed of an n-type organic mixed ion-electron conductor that is stable against ultraviolet rays, moisture, and heat, two electrode portions in direct contact with the active layer, and a separating layer that separates the two electrode portions from each other.

[0037] Figure 2 is a graph showing the energy levels of an n-type organic mixed ion-electron conductor according to an embodiment of the present invention in vacuum, moisture, and saline moisture environments.

[0038] Referring to Figure 2, it can be seen that the LUMO energy level of the n-type organic mixed ion-electron conductor is lower than the energy level of oxygen, so side reactions caused by oxygen are suppressed during device operation, thereby improving stability. In particular, it is characterized by the energy level being lower than that of oxygen even in high humidity and saline environments.

[0039] Figure 3 shows the measurement results of moisture stability of organic electrochemical transistor devices according to the embodiments and comparative examples of the present invention.

[0040] Referring to Figure 3, it can be seen that when the n-type PBDF material presented in the present invention is used, the performance of the organic electrochemical transistor is operated more stably in a high humidity environment than when the P-type PEDOT:PSS material is used.

[0041] Figure 4 is the result of measuring long-term stability in a moist environment through repeated measurements according to an embodiment of the present invention.

[0042] Referring to Fig. 4, in an embodiment of the present invention, the electrical performance of the n-type organic electrochemical transistor is maintained even after approximately 4,000 repeated bending cycles. It can be seen that performance of approximately 99.1%, 86.3%, and 50.65% is maintained at drain voltages of 0.01 V, 0.1 V, and 0.5 V, respectively.

[0043] Figure 5 shows the results of measuring the stability of an n-type organic electrochemical transistor before and after sterilization according to an example.

[0044] Referring to Fig. 5, when comparing the n-type organic electrochemical transistor according to an embodiment of the present invention before and after sterilization, it can be seen that the transconductance and surface uniformity are maintained within the margin of error without significant change. In other words, this means that there is no change in performance before and after sterilization. Meanwhile, sterilization was performed by storing the device for about 20 minutes in a high temperature environment of 121 °C and a high pressure environment of 15 psi.

[0045] Figure 6 is the result of the elasticity analysis of an organic electrochemical transistor according to an example.

[0046] Referring to Fig. 6, it can be seen that the skin-attached biosignal measuring device utilizing an organic electrochemical transistor according to the embodiment has an elasticity of approximately 200%.

[0047] Figure 7 shows the results of an analysis of device performance stability under repeated stretching of a skin-attached biosignal measuring device utilizing an organic electrochemical transistor according to an embodiment.

[0048] Referring to Fig. 7, it can be seen that electrical performance is maintained even after approximately 1,000 repeated stretching cycles.

[0049] FIG. 8 is a circuit diagram of a skin-attachable biosignal monitoring device utilizing an organic electrochemical transistor according to an embodiment.

[0050] Figure 9 shows a photograph of a skin-attached biosignal monitoring device utilizing an organic electrochemical transistor according to an embodiment and the biosignal measurement results.

[0051] Referring to Fig. 9, it can be seen that it can be stably attached even to curved skin and can stably measure biosignals for more than about 7 days.

[0052] 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.

[0053] 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 comprising an n-type mixed ion-electron conductor (OMIEC) capable of stable electrochemical doping / dedoping even in an oxygen and moisture environment, wherein the conductor comprises poly(benzodifurandione) (PBDF), and wherein the change in charge mobility and electrical conductivity of the conductor is maintained at ±10% or less even in a UV irradiation and high humidity environment. Claim 2 An organic electrochemical transistor according to claim 1, characterized in that the n-type mixed ion-electron conductor ensures oxidation stability by having a LUMO level of -4.9 eV or lower than the oxygen reduction potential, and performs a reversible electrochemical oxidation-reduction reaction in a 0.1 M NaCl or PBS aqueous solution environment. Claim 3 An organic electrochemical transistor according to claim 1, wherein the organic electrochemical transistor comprises a vertical channel structure formed by interposing an insulating layer between upper and lower electrodes, and additionally provides two voltage sensing terminals (Vsense1, Vsense2) to eliminate line resistance, thereby having a transconductance (gm) of 300 mS or more. Claim 4 An organic electrochemical transistor according to claim 1, characterized in that the rate of change of current and transconductance (gm) is 10% or less even after ultraviolet (UV, wavelength 256~365 nm) irradiation and autoclave sterilization (121℃, 1.2 atm, 20 min). Claim 5 An organic electrochemical transistor according to claim 1, wherein the organic electrochemical transistor is formed on a Parylene-C / SU-8 composite layer substrate having a thickness of 3 μm or less, and is characterized in that the rate of change of current is maintained at ±10% or less even under tensile deformation of 200% or more or repeated bending deformation of 1000 times or more. Claim 6 In claim 1, the organic electrochemical transistor operates at a driving voltage of 0.01 V or less and is capable of detecting biological signals (ECG, EMG, EEG, etc.) under 10 mV conditions. Claim 7 An organic electrochemical transistor according to claim 1, characterized in that the product of transconductance and volume capacitance (μC*) is 1500 F·cm¹·V¹·s¹ or more, and said μC* is maintained for 8 hours or more even in a high humidity environment of 85% or more relative humidity. Claim 8 A skin-attached biosignal monitoring device comprising an organic electrochemical transistor according to any one of claims 1 to 7, wherein the organic electrochemical transistor has a contact impedance of 10 kΩ or less upon skin contact and a signal-to-noise ratio (SNR) of 35 dB or more capable of stably detecting an ECG signal.

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