A stretchable electrode, a method of manufacturing the same, and a stretchable electronic device including the same

Abstract

The flexible electrode according to the present invention is a flexible electrode comprising silver nanowires and polydimethylsiloxane (PDMS), and comprises a gold coating layer formed on the silver nanowires.

Description

Technology Field

[0001] The present invention relates to a flexible electrode, a method for manufacturing the same, and a flexible electronic device comprising the same. Background Technology

[0003] Recently, interest in wearable electronics has intensified due to the promising potential for practical applications. Many advancements, including structural engineering and innovative material design, have paved the way for soft electronics such as skin-mounted and bio-implantable devices. In particular, research on inherently stretchable electronic materials and rubber composites has played a crucial role in developing fully soft organic electronic devices that can be closely mounted on the skin or implanted into the human body. While the development of these materials has been the primary focus, the interfaces between components are actually critical to the significant advancement of high-performance fully soft organic electronic devices.

[0004] Mainly the Fermi level (E) of the metal electrode F Contact resistance (R) caused by the difference in energy levels between the semiconductor and ) C ) limits the field-effect mobility of the organic transistor by hindering charge carrier movement at the interface.

[0005] R in a completely smooth organic transistor C Interface engineering to minimize has been overlooked, but for rigid and flat transistors, R C Efforts to reduce [this] have been studied, but this is incompatible with devices made solely of soft components. Therefore, there is an urgent need to develop appropriate approaches to form better interfaces for completely soft organic electronic devices.

[0006] Recently developed fully flexible organic transistors use polydimethylsiloxane containing silver nanowires (AgNWs / PDMS) as flexible electrodes and are promising due to their excellent electrical and mechanical properties. However, silver (E F,Ag(from -4.26 eV) and general p-type organic semiconductors (E HOMO It faces unique problems regarding energy barriers between -4.90 and -5.50 eV.

[0007] Gold (E) on the surface of AgNWs, a common solution F,Au When galvanic substitution is performed at -5.09 eV, ohmic contact is ensured between the flexible electrode and the organic semiconductor.

[0008] Nevertheless, this method often results in the non-uniform generation of gold particles in AgNWs due to vigorous redox reactions. In particular, if the gold coating is incomplete and the surface is rough, R in soft transistors C The size may increase. Furthermore, the gold coating of AgNWs in AgNWs / PDMS electrodes is inconsistent, and due to the chemical instability of silver, its application in soft biosensors is limited.

[0009] Therefore, a more promising approach is to achieve a complete and uniform gold coating through a simple process.

[0010] The aforementioned background technology is one that the inventor possessed or acquired in the process of deriving the contents of the disclosure of the present application, and it cannot be considered as prior art disclosed to the general public prior to the filing of this application. The problem to be solved

[0012] The present invention is intended to solve the aforementioned problems, and the objective of the present invention is to provide a uniformly gold-coated flexible electrode, a method for manufacturing the same, and a flexible electronic device including the same.

[0013] Another technical problem to be solved by the present invention is to provide a simple method for uniform gold coating on the surface of a polydimethylsiloxane-based flexible electrode containing silver nanowires, and a flexible electronic device technology utilizing the same.

[0014] However, the problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0016] The flexible electrode according to the present invention is a flexible electrode comprising silver nanowires and polydimethylsiloxane (PDMS), and comprises a gold coating layer formed on the silver nanowires.

[0017] According to one embodiment, the gold coating layer may be coated on the silver nanowire.

[0018] According to one embodiment, the silver nanowire may have a diameter of 75 nm to 105 nm and a length of 40 μm to 80 μm, and the thickness of the gold coating layer may be 300 nm to 400 nm.

[0019] A flexible organic transistor according to the present invention comprises a source-drain electrode including a flexible electrode according to the present invention; a gate electrode; an organic semiconductor; and an ion gel gate dielectric.

[0020] According to one embodiment, the contact resistance (Rc) of the flexible organic transistor may be 300 Ω·cm to 460 Ω·cm.

[0021] According to one embodiment, the mobility (μ) of the soft organic transistor FE ) is 6.4 cm 2 / V·s to 22 cm 2 It could be / V·s.

[0022] According to one embodiment, the organic semiconductor is P3HT(poly(3-hexylthiophene-2,5-diyl)), PTB7-Th(Poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene)-2-carboxylate-2-6-diyl)]) and It may comprise at least one selected from the group consisting of a mixture of PTB7-Th(Poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene)-2-carboxylate-2-6-diyl)]) and PDMS (Polydimethylsiloxane).

[0023] According to one embodiment, the ion gel gate dielectric may comprise at least one selected from the group consisting of PVDF-co-HFP (poly(vinylidene fluoride-co-hexafluoropropylene)), dehydrated EMIM-TFSI (1-Ethyl-3-methylimidazoliumbis(tri-fluoromethylsulfonyl)imide) and acetone.

[0024] A glucose sensor according to the present invention comprises: a flexible electrode according to the present invention; and an enzyme sensing membrane formed on the flexible electrode.

[0025] According to one embodiment, the enzyme sensing membrane may comprise glucose oxidase and titania sol-gel.

[0026] According to one embodiment, at a glucose concentration of 15 mM or less, the sensitivity of the glucose sensor is 0.238 μA·mM -1 ·cm -2 This is the case, and the detection limit of the glucose sensor may be 0.498 mM.

[0027] A method for manufacturing a flexible electrode according to the present invention comprises the steps of: preparing silver nanowires; applying liquid polydimethylsiloxane (PDMS) onto the silver nanowires to manufacture a flexible electrode; and forming a gold coating layer on the flexible electrode using a gold chloride (HAuCl4) solution containing sodium chloride (NaCl).

[0028] According to one embodiment, the concentration of the chloroauric acid (HAuCl4) solution may be 0.5 mM to 5 mM, and the concentration of the sodium chloride (NaCl) in the chloroauric acid (HAuCl4) solution may be 10 mM to 200 mM.

[0029] According to one embodiment, the step of forming a gold coating layer on the flexible electrode with a chloro-gold acid (HAuCl4) solution containing sodium chloride (NaCl) may induce slow galvanic displacement.

[0030] According to one embodiment, the method may further include the step of forming a gold coating layer on the flexible electrode using a chloro-gold acid (HAuCl4) solution containing sodium chloride (NaCl); and subsequently, the step of removing byproducts from the flexible electrode with the gold coating layer formed thereon using ammonia water (NH4OH). Effects of the invention

[0032] The present invention can provide a uniformly gold-coated flexible electrode, a method for manufacturing the same, and a flexible electronic device including the same. The present invention relates to a simple method for uniformly gold-coating the surface of a polydimethylsiloxane (PDMS)-based flexible electrode containing silver nanowires and a flexible electronic device technology utilizing the same. This is a simple method that enables uniform gold coating on the surface of silver nanowires by adding sodium chloride (NaCl) to a gold precursor solution of gold chloride acid (HAuCl4), dropping it onto polydimethylsiloxane containing silver nanowires, and inducing mild and slow galvanic substitution. Through the development of flexible organic transistor technology using a polydimethylsiloxane-based flexible electrode containing uniformly gold-coated silver nanowires, hole mobility can be significantly improved, thereby improving electrical characteristics. In addition, the glucose sensor developed in the present invention has a surface uniformly coated with gold, which clearly reduces the electrode oxidation effect of hydrogen peroxide (H2O2) generated during glucose detection, thereby enabling stable operation and providing a glucose sensor with improved device performance and stability. Brief explanation of the drawing

[0034] FIG. 1 shows a schematic diagram of a galvanic displacement process of a flexible electrode according to one embodiment and a comparative example of the present invention, and the inserted image is an SEM image of the flexible electrode. FIG. 2 is a time-dependent SEM image of a flexible electrode according to one embodiment and a comparative example of the present invention. Figure 3 is a cyclic voltammetry graph of a 0.5 mM HAuCl4 solution with no NaCl added and with various concentrations of NaCl added, according to one embodiment and a comparative example of the present invention. FIG. 4 is a schematic diagram of a flexible electrode and an EDS elemental mapping of the flexible electrode according to one embodiment and a comparative example of the present invention. FIG. 5 is an optical image of a fully flexible organic transistor array and an inset of a schematic full-resolution diagram of a single fully flexible organic transistor according to one embodiment and a comparative example of the present invention, (a) a schematic diagram of charge injection between an organic semiconductor and a microparticle Au-coated AgNWs / PDMS electrode, and (c) a schematic diagram of charge injection between an organic semiconductor and a uniform Au-coated AgNWs / PDMS electrode. FIG. 6 is a schematic exploded view and optical image of a flexible organic transistor according to one embodiment of the present invention. FIG. 7 is a diagram showing (a) the molecular structural formula of PTB7-Th and (b) the energy levels of PTB7-Th, gold, and silver according to one embodiment of the present invention. FIG. 8 shows (a) C using a 0.5 mM HAuCl4 solution according to one embodiment and a comparative example of the present invention. NaCl Contact resistance (R) of a soft organic transistor prepared while varying C Graph showing W) (b) C using 0.5 mM HAuCl4 solution NaCl Graph showing the transfer characteristics of soft organic transistors prepared while varying and (c) C using a 0.5 mM HAuCl4 solution NaCl Mobility (μ) of a soft organic transistor prepared while varying FE This is a graph representing ). FIG. 9 is a schematic diagram of a flexible semiconductor PTB7-Th / PDMS composite according to one embodiment of the present invention, (b) AFM images of the PTB7-Th / PDMS composite in height (left) and phase (right) modes, and (c) a molecular electrostatic potential map of PTB7-Th and a dipole moment of PTB7-Th. FIG. 10 is (a) sequential optical image and (b) AFM height image of PTB7-Th at various mechanical strains according to one embodiment and a comparative example of the present invention. FIG. 11 shows (a) an optical image of an array of fully flexible organic transistors according to one embodiment of the present invention and an inset of an enlarged optical image of a single device (b) mobility (μ) of the fully flexible organic transistors. FE (c) a graph showing the distribution and (c) a graph showing the mobility (μ) and maximum tensile strength values ​​of a fully flexible organic transistor and a reported fully flexible organic transistor. FIG. 12 shows the transfer characteristics under strain parallel to (a) the channel length direction and (b) the transfer characteristics under strain perpendicular to (c) the μ under strain parallel (upward) and perpendicular (downward) to the channel length direction of a fully flexible organic transistor according to one embodiment of the present invention. FE and V TH This is a graph showing the change. FIG. 13 shows the transfer characteristics after (a) iterative deformation parallel to the channel length direction and (b) the transfer characteristics after iterative deformation perpendicular to the channel length direction and (c) μ after iterative deformation parallel (up) and perpendicular (down) to the channel length direction of a fully flexible organic transistor according to an embodiment of the present invention. FE and V TH This is a graph showing the change. FIG. 14 is a schematic diagram showing (a) an optical image and a schematic exploded view, (b) an SEM image of the sensing area of ​​the working electrode, and (c) a sensing mechanism of a glucose sensor according to one embodiment of the present invention. FIG. 15 is a graph showing (a) the electrochemical stability of AgNWs / PDMS and Au-coated AgNWs / PDMS electrodes in a 30 mM H2O2 solution and (b) the chronoamperometric current response of a soft glucose sensor at various glucose concentrations according to one embodiment of the present invention. FIG. 16 is a graph showing (a) a calibration curve of a soft glucose sensor using a Michaelis-Menten model-based fitting curve and (b) the sensitivity of a soft glucose sensor according to one embodiment of the present invention. FIG. 17 is an optical image of a flexible glucose sensor applicable as a bioimplantable device to (a) dermis and (b) liver according to one embodiment of the present invention. Specific details for implementing the invention

[0035] Hereinafter, embodiments are described in detail with reference to the attached drawings. However, various modifications may be made to the embodiments, and thus the scope of the patent application is not limited or restricted by these embodiments. It should be understood that all modifications, equivalents, and substitutions to the embodiments are included within the scope of the rights.

[0036] The terms used in the embodiments are for illustrative purposes only and should not be interpreted as intended to be limiting. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "comprising" or "having" are intended to indicate 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.

[0037] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the embodiments pertain. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0038] In addition, when describing with reference to the attached drawings, identical components are assigned the same reference numeral regardless of the drawing symbols, and redundant descriptions thereof are omitted. In describing the embodiments, if it is determined that a detailed description of related prior art could unnecessarily obscure the essence of the embodiments, such detailed description is omitted. Furthermore, when describing the components of the embodiments, terms such as first, second, A, B, (a), (b), etc., may be used. These terms are intended merely to distinguish the components from other components, and the essence, order, or sequence of the components is not limited by these terms. Where it is stated that a component is "connected," "combined," or "joined" to another component, it should be understood that while the component may be directly connected or joined to the other component, another component may also be "connected," "combined," or "joined" between each component.

[0039] Components included in any one embodiment and components having common functions shall be described using the same names in other embodiments. Unless otherwise stated, the descriptions given in any one embodiment may also apply to other embodiments, and specific descriptions shall be omitted to the extent of overlap.

[0041] The flexible electrode according to the present invention is a flexible electrode comprising silver nanowires and polydimethylsiloxane (PDMS), and comprises a gold coating layer formed on the silver nanowires.

[0042] FIG. 1 shows a schematic diagram of a galvanic displacement process of a flexible electrode according to one embodiment and a comparative example of the present invention, and the inserted image is an SEM image of the flexible electrode.

[0043] Referring to FIG. 1, a galvanic substitution process for Au coating on exposed AgNWs of a flexible electrode containing silver nanowires and polydimethylsiloxane (PDMS) is schematically described, comparing the case using an HAuCl4 solution with NaCl (Example) and the case using an HAuCl4 solution without NaCl (Comparative Example). Conventional Au coating via galvanic substitution using an HAuCl4 solution causes an intense reaction that produces a particulate and non-uniform Au layer, whereas the inclusion of NaCl in the solution facilitates a uniform and complete coating of gold (Au) on the flexible electrode containing silver nanowires and polydimethylsiloxane (PDMS), as can be seen in the inset of the scanning electron microscope (SEM) image.

[0045] According to one embodiment, the gold coating layer may be coated on the silver nanowire.

[0046] FIG. 2 is a time-dependent SEM image of a flexible electrode according to one embodiment and a comparative example of the present invention.

[0047] Referring to Fig. 2, SEM images of exposed AgNWs on a flexible electrode containing silver nanowires and polydimethylsiloxane (PDMS) are shown over time during the galvanic displacement process. (a) a solution containing only HAuCl4 (Comparative Example) and (b) a solution containing 50 mM NaCl (Example) can be compared. When electrically displacement was performed with the solution containing only HAuCl4, no significant change was observed after 2 minutes, indicating that the reaction was completed rapidly and a particulate and non-uniform Au coating was formed on the AgNWs.

[0048] In contrast, the HAuCl4 solution containing 50 mM NaCl completed the reaction in about 40 minutes, achieving a uniform Au coating rate. Furthermore, because the short treatment period is not sufficient to negatively affect the AgNWs, NaCl does not cause corrosion or structural damage to the flexible electrode containing silver nanowires and polydimethylsiloxane (PDMS) during galvanic displacement. The HAuCl4 concentration (C(HAuCl4)) does not affect the Au coating on the AgNWs even after 60 minutes. NaCl plays an important role in achieving uniform Au formation on AgNWs.

[0049] The mechanism of uniform Au coating using HAuCl4 with NaCl is attributed to two main phenomena.

[0050] (1) Decrease in reaction rate and negative change in reduction potential according to Le Chatelier's principle

[0051] (2) Prevention of AgCl precipitation through the formation of soluble complexes.

[0052] AuCl4 - and Ag + The reaction induced by the difference in reduction potential between them can be explained by the following Equation 1.

[0054] [Equation 1]

[0055] 3Ag(s) + AuCl4 - (aq) → Au(s) + 3Ag + (aq) + 4Cl - (aq) → Au(s) + 3AgCl(s) + Cl - (aq)

[0057] In the presence of NaCl, excess Cl - It shifts the equilibrium to the left according to Le Chatelier's principle, slowing down the galvanic displacement reaction.

[0058] Also AuCl4 - / Au 0 and Ag + / Ag 0The difference in reduction potential between them is closely related to the reaction rate.

[0059] Figure 3 is a cyclic voltammetry graph of a 0.5 mM HAuCl4 solution with no NaCl added and with various concentrations of NaCl added, according to one embodiment and a comparative example of the present invention.

[0060] Referring to Fig. 3, the cathode scan is Au 0 It exhibits a peak at 0.56 V relative to Ag / AgCl reduced to, and shifts to 0.35 V at 50 mM NaCl, indicating a galvanic substitution driving force Indicates that it has decreased. C NaCl AuCl4 - / Au 0 Although it does not significantly affect the reduction potential of, the anodic peak is C NaCl The higher this is, the more it shifts to the negative, Au 0 Oxidation of becomes easier and the equilibrium is AuCl4 - This implies a shift toward formation. Furthermore, AgCl precipitation intensifies the formation of particulate Au, which is due to excess Cl. - Soluble Ag complex (AgCl2) under certain conditions - It is alleviated by the formation of ).

[0062] According to one embodiment, the silver nanowire may have a diameter of 75 nm to 105 nm and a length of 40 μm to 80 μm, and the thickness of the gold coating layer may be 300 nm to 400 nm.

[0063] According to one embodiment, the silver nanowire may have a diameter of 75 nm to 105 nm; 80 nm to 105 nm; 85 nm to 105 nm; 90 nm to 105 nm; 95 nm to 105 nm; 100 nm to 105 nm; 75 nm to 100 nm; 75 nm to 95 nm; 75 nm to 90 nm; 75 nm to 85 nm; 75 nm to 80 nm; 80 nm to 90 nm; 85 nm to 95 nm; 90 nm to 100 nm.

[0064] According to one embodiment, if the diameter of the silver nanowire is less than 75 nm, there may be a problem with the etching of the silver nanowire due to a violent redox reaction during the galvanic substitution process, and if it is greater than 105 nm, there may be a problem with incomplete gold coating during the galvanic substitution process.

[0065] According to one embodiment, the silver nanowire may have a length of 40 μm to 80 μm; 50 μm to 80 μm; 60 μm to 80 μm; 70 μm to 80 μm; 40 μm to 70 μm; 40 μm to 60 μm; 40 μm to 50 μm; 45 μm to 55 μm; 50 μm to 60 μm; 55 μm to 65 μm; 60 μm to 70 μm; 65 μm to 75 μm.

[0066] According to one embodiment, if the length of the silver nanowire is less than 40 μm, there may be a problem with etching the silver nanowire due to a violent redox reaction during the galvanic substitution process, and if it is greater than 80 μm, there may be a problem with incomplete gold coating during the galvanic substitution process.

[0067] According to one embodiment, the thickness of the gold coating layer may be 300 nm to 400 nm; 320 nm to 400 nm; 340 nm to 400 nm; 360 nm to 400 nm; 380 nm to 400 nm; 300 nm to 380 nm; 300 nm to 360 nm; 300 nm to 340 nm; 300 nm to 320 nm; 320 nm to 350 nm; 330 nm to 360 nm; 350 nm to 380 nm.

[0068] According to one embodiment, if the thickness of the gold coating layer is less than 300 nm, there may be a problem of increased contact resistance with the organic semiconductor during transistor fabrication, and if it is greater than 400 nm, it is a result of excessive etching of internal silver nanowires during the galvanic substitution process, and there may be a problem of reduced conductivity of the electrode as a result.

[0069] FIG. 4 is a schematic diagram of a flexible electrode and an EDS elemental mapping of the flexible electrode according to one embodiment and a comparative example of the present invention.

[0070] Referring to Figure 4, the morphology of Au-coated AgNWs prepared using a solution containing HAuCl4 (Comparative Example) and a solution containing 50 mM NaCl (Example) can be seen.

[0071] Figure 4 (a) shows a schematic diagram of a flexible electrode according to a comparative example, which is a HAuCl4 solution without NaCl, and (b) shows the EDS elemental mapping of the flexible electrode, which can be seen to form particulate Au and cause severe AgNW loss. This is due to the reaction stoichiometry and the fast electrochemical reaction rate.

[0072] Figure 4 (c) is a schematic diagram of a flexible electrode according to an example in which 50 mM NaCl is added to a HAuCl4 solution, and (b) is a diagram showing the EDS elemental mapping of the flexible electrode. It can be seen that when the induced reaction slows down, galvanic substitution occurs mainly at the outer atoms of the AgNWs, and as a result, a mainly uniform Au coating is formed on the AgNWs, and partially hollow Au-coated AgNWs are formed, so that the electrical properties are not degraded.

[0074] A flexible organic transistor according to the present invention comprises a source-drain electrode including a flexible electrode according to the present invention; a gate electrode; an organic semiconductor; and an ion gel gate dielectric.

[0075] FIG. 5 is an optical image of a fully flexible organic transistor array and an inset of a schematic full-resolution diagram of a single fully flexible organic transistor according to one embodiment and a comparative example of the present invention, (a) a schematic diagram of charge injection between an organic semiconductor and a microparticle Au-coated AgNWs / PDMS electrode, and (c) a schematic diagram of charge injection between an organic semiconductor and a uniform Au-coated AgNWs / PDMS electrode.

[0076] Referring to Fig. 5(a), the optical image and inset of the fully flexible organic transistor array are schematic full exploded views of a single fully flexible organic transistor, and an 8 × 8 array of fully flexible organic transistors fabricated using an Au-coated AgNWs / PDMS source-drain electrode, an AgNWs / PDMS gate electrode, a flexible organic semiconductor, and an ion gel gate dielectric can be seen.

[0077] Referring to Figure 5(b), which is a schematic diagram of charge injection between an organic semiconductor and a microparticle Au-coated AgNWs / PDMS electrode, conventional Au deposition on AgNWs / PDMS generally leads to adverse charge transfer between the organic semiconductor and the soft electrode.

[0078] Referring to FIG. 5(c), a schematic diagram of charge injection between an organic semiconductor and a uniformly Au-coated AgNWs / PDMS electrode is shown, where the uniform Au coating on the AgNWs / PDMS enables efficient charge transfer, thereby R C It reduces [unclear value] and improves device performance such as charge carrier mobility. Therefore, achieving a uniform Au coating on AgNWs / PDMS is important for the high performance of fully flexible organic transistors.

[0080] According to one embodiment, the contact resistance (Rc) of the flexible organic transistor may be 300 Ω·cm to 460 Ω·cm.

[0081] According to one embodiment, the contact resistance (Rc) of the flexible organic transistor is 300 Ω·cm to 460 Ω·cm; 330 Ω·cm to 460 Ω·cm; 360 Ω·cm to 460 Ω·cm; 390 Ω·cm to 460 Ω·cm; 420 Ω·cm to 460 Ω·cm; 440 Ω·cm to 460 Ω·cm; 300 Ω·cm to 440 Ω·cm; 300 Ω·cm to 420 Ω·cm; 300 Ω·cm to 400 Ω·cm; 300 Ω·cm to 380 Ω·cm; 300 Ω·cm to 360 Ω·cm; 300 Ω·cm to 320 Ω·cm; It may be 350 Ω·cm to 400 Ω·cm; 380 Ω·cm to 410 Ω·cm; 400 Ω·cm to 450 Ω·cm.

[0082] According to one embodiment, if the contact resistance (Rc) of the flexible organic transistor is less than 300 Ω·cm, there may be a problem with the process causing a decrease in the performance of the flexible organic transistor, and if it exceeds 460 Ω·cm, it may be caused by the gold coating not being uniform and complete during galvanic substitution, and there may be a problem with a decrease in field-effect mobility during transistor fabrication.

[0083] FIG. 6 is a schematic exploded view and optical image of a flexible organic transistor according to one embodiment of the present invention.

[0084] Referring to Figure 6, it can be seen that the organic transistors are fabricated using PTB7-Th and ion gel as the organic semiconductor and gate dielectric, respectively.

[0085] FIG. 7 is a diagram showing (a) the molecular structural formula of PTB7-Th and (b) the energy levels of PTB7-Th, gold, and silver according to one embodiment of the present invention.

[0086] Referring to FIG. 7, the highest occupied molecular orbital (HOMO) level (E) is significantly negative compared to the Fermi level of silver. HOMO PTB7-Th selected at = -5.24 eV is a significant R of the organic transistor C Emphasizing, clear R depending on the morphology of Au-coated AgNWs / PDMS C You can see the change.

[0087] FIG. 8 shows (a) C using a 0.5 mM HAuCl4 solution according to one embodiment and a comparative example of the present invention. NaCl Contact resistance (R) of a soft organic transistor prepared while varying C Graph showing W) (b) C using 0.5 mM HAuCl4 solution NaCl Graph showing the transfer characteristics of soft organic transistors prepared while varying and (c) C using 0.5 mM HAuCl4 solution NaCl Mobility (μ) of a soft organic transistor prepared while varying FE This is a graph representing ).

[0088] Various C NaCl R of a PTB7-Th-based organic transistor based on an Au-coated AgNWs / PDMS electrode prepared with 0.5 mM HAuCl4 solution C was investigated using the transition length method (TLM). The device channel length (L CH) varied from 30 to 400 μm, and the channel width (W CH ) was fixed at 1250 μm.

[0089] Referring to Fig. 8(a), C using a 0.5 mM HAuCl4 solution NaCl Contact resistance (R) of a soft organic transistor prepared while varying C A graph representing W), showing the device's R C W is 50 mM C in HAuCl4 solution NaCl It decreased significantly to (387 ± 72 Ω·cm), which was lower compared to the device using a pure AgNWs / PDMS electrode (849 ± 162 Ω·cm) and the Au-coated device in a dedicated HAuCl4 solution (655 ± 147 Ω·cm). High C NaCl R that can be ignored in C The change in W is consistent with the observed morphological trend of 50 mM C NaCl The above suggests a saturated Au coverage rate.

[0090] These results suggest that using a HAuCl4 solution containing NaCl for galvanic substitution of Au coatings in AgNWs / PDMS can be an effective method to enhance charge carrier transport between the soft electrode and the organic semiconductor.

[0091] In addition, various C NaCl The electrical characteristics of the device were further evaluated using Au-coated AgNWs / PDMS electrodes prepared by galvanic displacement. For consistent comparison, L of all devices CH W CH The values ​​were fixed at 100 and 1250 μm, respectively. All devices exhibited typical p-channel behavior.

[0092] Referring to Fig. 8(b), C using a 0.5 mM HAuCl4 solution NaCl A graph showing the transfer characteristics of soft organic transistors prepared by varying C NaClA clear performance difference was observed in the device made with a solution containing [unclear text]. The ON current of the device was [unclear text] of the C in the HAuCl4 solution. NaCl This increases and 50 mM C NaC It clearly improved as it became saturated in l.

[0094] According to one embodiment, the mobility (μ) of the soft organic transistor FE ) is 6.4 cm 2 / V·s to 22 cm 2 It could be / V·s.

[0095] According to one embodiment, the mobility (μ) of the soft organic transistor FE ) is 6.4 cm 2 / V·s to 22 cm 2 / V·s; 7.0 cm 2 / V·s to 22 cm 2 / V·s; 9.0 cm 2 / V·s to 22 cm 2 / V·s; 11 cm 2 / V·s to 22 cm 2 / V·s; 15 cm 2 / V·s to 22 cm 2 / V·s; 17 cm 2 / V·s to 22 cm 2 / V·s; 20 cm 2 / V·s to 22 cm 2 / V·s; 6.4 cm 2 / V·s to 20 cm 2 / V·s; 6.4 cm 2 / V·s to 18 cm 2 / V·s; 6.4 cm 2 / V·s to 16 cm 2 / V·s; 6.4 cm 2 / V·s to 12 cm 2 / V·s; 6.4 cm 2 / V·s to 10 cm 2 / V·s; 6.4 cm 2 / V·s to 8 cm 2 / V·s; 8 cm2 / V·s to 15 cm 2 / V·s; 10 cm 2 / V·s to 17 cm 2 / V·s; 12 cm 2 / V·s to 20 cm 2 It could be / V·s;

[0096] According to one embodiment, the mobility (μ) of the soft organic transistor FE ) is 6.4 cm 2 If it is less than / V·s, the main cause is likely the degradation of organic semiconductor coating uniformity due to impurities, and there may be a problem where the magnitude of the decrease in transistor mobility increases during stretching, and 22 cm 2 If / V·s is exceeded, there may be a problem where the performance of the above-mentioned soft organic transistor deteriorates due to process issues.

[0097] Referring to Fig. 8(c), C using a 0.5 mM HAuCl4 solution NaCl Mobility (μ) of a soft organic transistor prepared while varying FE A graph showing ), a device (C) using an AgNWs / PDMS electrode without Au coating and an AgNWs / PDMS electrode with Au coating. NaCl = using 0 mM) were 1.30 ± 0.89 and 2.42 ± 0.62 cm⁻¹, respectively. 2 Average μ of / V·s FE While showed, 50 mM C NaCl The device using is 7.45 ± 0.64 cm 2 Average μ of / V·s FE Achieved. This μ FE The trend is R C There is a correlation with change.

[0098] Additionally, the threshold swing (ss) was 325.21 ± 35.48 mV / dec at 50 mM C in a device with an Au-coated AgNWs / PDMS electrode prepared without NaCl. NaClIt decreased to 200.19 ± 37.69 mV / dec in the device fabricated using [method]. This decrease is attributed to the enhanced charge carrier injection efficiency between the semiconductor and the electrode through the uniform Au coating on AgNWs / PDMS using NaCl. The threshold voltage (V) TH ) did not change significantly across the entire device regardless of whether NaCl was used. This is due to the inherently low operating voltage characteristics of the ion-gating operation of this organic transistor, V TH This may be because only trivial and undetectable changes occur in μ FE Similar performance improvements were also observed in organic transistors based on poly(3-hexylthiophene-2,5-diyl) (P3HT), another p-type organic semiconductor with a HOMO level of -5.0 eV. These results highlight the diversity of approaches for organic transistors using AgNWs / PDMS electrodes.

[0099] FIG. 9 is a schematic diagram of a flexible semiconductor PTB7-Th / PDMS composite according to one embodiment of the present invention, (b) AFM images of the PTB7-Th / PDMS composite in height (left) and phase (right) modes, and (c) a molecular electrostatic potential map of PTB7-Th and a dipole moment of PTB7-Th.

[0100] A high-performance, fully flexible organic transistor composed entirely of flexible materials was demonstrated using an Au-coated AgNWs / PDMS electrode prepared with a 0.5 mM HAuCl4 solution containing 50 mM NaCl. The flexible electrode exhibits excellent robustness in electrical characteristics at 80% mechanical strain without apparent degradation of the Au coating.

[0101] PTB7-Th / PDMS, a polymer blend containing PTB7-Th and PDMS, was used as a soft organic semiconductor. This choice was driven by the significant performance degradation observed in transistors composed solely of PTB7-Th at 80% mechanical strain.

[0102] Numerous cases involving blends of polar semiconductor polymers and non-polymer insulating polymers exhibit phase separation, a phenomenon known as the confinement effect.

[0103] Referring to Fig. 9(a), a schematic diagram of a flexible semiconductor PTB7-Th / PDMS composite shows that a continuously connected semiconductor network is formed due to the confinement effect.

[0104] Referring to Figure 9(b), which shows AFM images of the PTBT-Th / PDMS composite in height (left) and phase (right) modes, the atomic force microscope (AFM) images can confirm clear lateral phase separation compared to the uniformly dispersed phase in PTB7-Th / PDMS.

[0105] It is known that the morphology of PTB7-Th / PDMS blends, induced by strong intermolecular interactions, is primarily influenced by the dipole moments and planarity of semiconductor molecules.

[0106] Referring to Figure 9(c), which shows the molecular electrostatic potential map and the dipole moment of PTB7-Th, PTB7-Th actually has a significantly large dipole moment of 5.25 D estimated using density functional theory (DFT).

[0107] However, the dihedral angles between neighboring benzodithiophene and thieno[3,4-b]thiophene units obtained at 27.67° and 15.22° show relatively low planarity compared to reported semiconductors with high planarity, which indicates that dipole moments rather than planarity contribute primarily to inducing confinement effects.

[0108] FIG. 10 shows (a) sequential optical images and (b) AFM height images of PTB7-Th at various mechanical strains according to one embodiment and a comparative example of the present invention. The mechanical robustness of the PTB7-Th / PDMS film was confirmed by OM and AFM images.

[0109] Referring to Fig. 10(a), sequential optical images of PTB7-Th at various mechanical strains, the PTB7-Th / PDMS film did not show clear damage at mechanical strains up to 80%.

[0110] Referring to Fig. 10(b), no cracks were observed in the PTB7-Th / PDMS film even at a strain of 80%. This resilience is due to the elastic domains absorbing the strain and minimizing the stress in the fiber network. The typical output and transfer characteristics and hysteresis behavior of the fully flexible transistor fabricated using the PTB7-Th / PDMS blend are characteristic of typical p-channel characteristics.

[0111] FIG. 11 shows (a) an optical image of an array of fully flexible organic transistors according to one embodiment of the present invention and an inset of an enlarged optical image of a single device (b) mobility (μ) of the fully flexible organic transistors. FE (c) a graph showing the distribution and (c) a graph showing the mobility (μ) and maximum tensile strength values ​​of a fully flexible organic transistor and a reported fully flexible organic transistor.

[0112] The confinement effect of the flexible semiconductor, combined with the low contact resistance between the semiconductor and the electrode, can produce a synergistic effect on the high performance of fully flexible organic transistors.

[0113] Referring to FIG. 11 (a) and (b), (a) an optical image of an array of fully flexible organic transistors and an inset of an enlarged optical image of a single device, (b) the mobility (μ) of the fully flexible organic transistors. FE This is a graph showing the distribution, and for such transistors, the average μ FE Ga 13.09 ± 4.17 cm 2 / V·s and the highest μ FE is 21.87 cm 2 You can confirm that it is / V·s.

[0114] Referring to Figure 11 (c), the graph shows the mobility (μ) and maximum tensile strength values ​​of a fully soft organic transistor and a reported fully soft organic transistor, and it can be seen that the mobility of the previously reported fully soft organic transistor is surpassed.

[0115] FIG. 12 shows the transfer characteristics under strain parallel to (a) the channel length direction and (b) the transfer characteristics under strain perpendicular to (c) the μ under strain parallel (upward) and perpendicular (downward) to the channel length direction of a fully flexible organic transistor according to one embodiment of the present invention. FE and V TH This is a graph showing the change.

[0116] Referring to Fig. 12, the typical electrical characteristics of the device at various mechanical strains (0%, 20%, 50%, 80%, and after release to 0%) showed reliable operation.

[0117] In particular, L CH No physical damage or severe performance degradation was observed even at 80% strain along the direction and perpendicularly. μ FE was calculated considering the change in channel shape at strain. L CH μ in mechanical strain applied along the direction FE and V TH 16.15 cm at 0% respectively 2 11.51 cm at 80% of / V·s 2 / V·s showed a moderate change from -2.33 V to -2.20 V. When the mechanical strain was completely released, μ FE and V TH Each is 15.36 cm 2 It returned to / V·s and -2.09 V.

[0118] L CH For a device subjected to deformation perpendicular to the direction, μ FE 14.04 cm at 0% 2 / V·s, 7.42 cm at 80% 2 / V·s, 13.01 cm at 0% 2 / V·s) and V TH A similar trend was observed in all of them (-2.35 V at 0%, -2.33 V at 80%, and -2.36 V at 0%). This is L CH It is equivalent to deformation in the direction. To evaluate the durability of a fully ductile transistor under mechanical stress, we L CH The resistance to fatigue was further investigated through repetitive stretching / releasing cycles of the device under tensile strain of up to 80% along the direction and vertically.

[0119] FIG. 13 shows the transfer characteristics after (a) iterative deformation parallel to the channel length direction and (b) the transfer characteristics after iterative deformation perpendicular to the channel length direction and (c) μ after iterative deformation parallel (up) and perpendicular (down) to the channel length direction of a fully flexible organic transistor according to an embodiment of the present invention. FE and V TH This is a graph showing the change.

[0120] Referring to Fig. 13, typical transfer characteristics of the device are shown after 1,000 stretching / releasing cycles at 80% strain, demonstrating that there is no significantly substantial performance degradation. The important point is μ FE and V TH ga showed only minor changes. μ FE is 14.15 cm 2 10.05 cm at / V·s 2 It decreased to / V·s, and V TH is L CH After 1000 stretches / releasings along the direction, it moved from -2.10 V to -2.24 V.

[0121] Also, L CH A similar trend was observed for circulatory stretching perpendicular to the direction. μ FE 13.18 cm after 1000 cycles 2 8.54 cm at / V·s 2 / V·s to, V THIt changed from -2.36 V to -2.31 V. These results confirm the robust mechanical durability of the device while maintaining functional stability through a wide range of stress cycles.

[0122] A fully flexible organic transistor according to one embodiment of the present invention may be a fully flexible transistor that undergoes various mechanical deformations including stretching, bending, and twisting, and if all elastic materials are used in the device, the fully flexible transistor can be easily deformed without physical damage. These results may indicate that an approach of adding NaCl to a HAuCl4 solution to effectively coat the exposed AgNWs of an AgNWs / PDMS electrode provides a practical means for realizing a high-performance fully flexible electronic device.

[0124] According to one embodiment, the organic semiconductor is P3HT(poly(3-hexylthiophene-2,5-diyl)), PTB7-Th(Poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene)-2-carboxylate-2-6-diyl)]) and It may comprise at least one selected from the group consisting of a mixture of PTB7-Th(Poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene)-2-carboxylate-2-6-diyl)]) and PDMS (Polydimethylsiloxane).

[0126] According to one embodiment, the ion gel gate dielectric may comprise at least one selected from the group consisting of PVDF-co-HFP (poly(vinylidene fluoride-co-hexafluoropropylene)), dehydrated EMIM-TFSI (1-Ethyl-3-methylimidazoliumbis(tri-fluoromethylsulfonyl)imide) and acetone.

[0127] According to one embodiment, the ion gel gate dielectric may comprise all of PVDF-co-HFP (poly(vinylidene fluoride-co-hexafluoropropylene)), dehydrated EMIM-TFSI (1-Ethyl-3-methylimidazoliumbis(tri-fluoromethylsulfonyl)imide) and acetone, and the ion gel gate dielectric may be prepared by mixing the materials.

[0129] A glucose sensor according to the present invention comprises: a flexible electrode according to the present invention; and an enzyme sensing membrane formed on the flexible electrode.

[0130] Mechanical softness and chemical inertness are essential for bioimplantable devices. Although AgNWs / PDMS electrodes have been used in various bioelectronics, their inherent vulnerability to chemical oxidation poses challenges for a wide range of applications.

[0131] In particular, soft-form implantable glucose sensors that monitor interstitial fluid glucose concentration offer significant benefits for diabetes management due to the high correlation between blood and interstitial fluid glucose levels. While AgNWs / PDMS electrodes are promising and useful, they are not suitable for soft glucose sensors. This is because conventional glucose sensors are enzymatic and generate H2O2 during glucose detection, which negatively affects the stability of AgNWs.

[0132] Therefore, the approach of complete Au coating on the exposed AgNWs of the AgNWs / PDMS electrode significantly improves resistance to severe oxidation. By providing enhanced chemical resistance to H2O2, it can ensure reliable sensing capabilities.

[0133] A flexible glucose sensor was fabricated using a uniformly Au-coated AgNWs / PDMS electrode prepared by electrically replacing it with HAuCl4 containing 50 mM NaCl, i.e., a flexible electrode according to the present invention.

[0134] FIG. 14 is a schematic diagram showing (a) an optical image and a schematic exploded view, (b) an SEM image of the sensing area of ​​the working electrode, and (c) a sensing mechanism of a glucose sensor according to one embodiment of the present invention.

[0135] Referring to Fig. 14 (a), (a) an optical image and schematic exploded view of a glucose sensor according to one embodiment of the present invention , It consists of an enzyme sensing membrane and three electrodes. The working electrode (WE), counter electrode (CE), and reference electrode (RE) comprise a flexible electrode according to the present invention.

[0137] According to one embodiment, the enzyme sensing membrane may comprise glucose oxidase and titania sol-gel.

[0138] Referring to FIG. 14(b), an SEM image of the sensing region of the working electrode of a glucose sensor according to one embodiment of the present invention is shown, in which glucose oxidase (GOD) and titania sol-gel were used for the enzyme sensing membrane due to their specificity and stability. The GOD layer formed a particle shape by hydrolyzing with GOD and isoperoxide and immobilizing it on the sensing electrode. The GOD immobilized on the electrode accelerates the degradation of glucose to produce H2O2 and consequently generates electrons. .

[0139] Referring to FIG. 14(c), a schematic diagram illustrating the sensing mechanism of a glucose sensor according to one embodiment of the present invention is shown, wherein the current measured by the sensor is determined according to the glucose concentration. A complete Au coating on the exposed AgNWs of an AgNWs / PDMS electrode prepared using HAuCl4 containing NaCl provides excellent electrochemical inertness. This characteristic is important in oxidizing environments, such as those containing H2O2. The AgNWs / PDMS electrode exhibits stability in mild environments (e.g., phosphate-buffered saline, PBS) but is susceptible to oxidation under oxidizing conditions.

[0141] According to one embodiment, at a glucose concentration of 15 mM or less, the sensitivity of the glucose sensor is 0.238 μA·mM -1 ·cm -2 This is the case, and the detection limit of the glucose sensor may be 0.498 mM.

[0142] According to one embodiment, at a glucose concentration of 15 mM or less, the sensitivity of the glucose sensor is 0.238 μA·mM -1 ·cm -2 If it is less than that, it is likely due to incomplete coating of the GOD and titania sol-gel layers, which reduces the linear detection range of glucose and may result in unstable glucose detection problems.

[0143] According to one embodiment, at a glucose concentration of 15 mM or less, the detection limit of the glucose sensor is such that if it exceeds 0.498 mM, it is due to incomplete coating of the GOD and titania sol-gel layer, which reduces the linear detection range of glucose and may result in unstable detection of glucose.

[0144] FIG. 15 is a graph showing (a) the electrochemical stability of AgNWs / PDMS and Au-coated AgNWs / PDMS electrodes in a 30 mM H2O2 solution and (b) the chronoamperometric current response of a soft glucose sensor at various glucose concentrations according to one embodiment of the present invention.

[0145] Referring to Fig. 15(a), it can be observed that the current flow of pure AgNWs / PDMS decreases dramatically at an applied voltage of 400 mV in a 30 mM H2O2 solution. Conversely, the particulate Au-coated electrode prepared using HAuCl4 without NaCl shows a decrease in current over time. However, the fully Au-coated electrode prepared using NaCl in the HAuCl4 solution exhibits negligible changes. This stability is attributed to the prevention of electrochemical etching of Ag by H2O2. In other words, the fully Au-coated AgNWs / PDMS maintain electrical performance even in an oxidizing environment. Therefore, fully Au-coated AgNWs / PDMS can represent an effective approach for enzyme-based soft glucose sensors.

[0146] Referring to Figure 15(b), the graph shows the chronoamperometric current response of a soft glucose sensor at various glucose concentrations. A constant potential of 400 mV was applied to the RE for chronoamperometric measurements of the glucose sensor at glucose concentrations of 0 to 30 mM. This range adequately covers normal and diabetic glucose levels in human interstitial fluid (approx. 2–23 mM). It clearly demonstrates the sensor's current response to various glucose concentrations. In the range of 0 to 15 mM, the sensor exhibits a linear relationship between glucose concentration and measured current, and the sensitivity is 0.238 μA·mM -1 ·cm -2 The limit of detection (LOD) is 0.498 mM. This sensing performance is significantly superior to that of a soft glucose sensor fabricated using an Au-coated AgNWs / PDMS electrode prepared via galvanic replacement without NaCl. In particular, the non-uniform Au coating exposes AgNWs to H2O2, causing electrochemical degradation of the electrode; as a result, the sensing function becomes unstable and the sensitivity is 0.168 μA·mM -1 ·cm -2 It can be lowered to.

[0147] FIG. 16 is a graph showing (a) a calibration curve of a soft glucose sensor using a Michaelis-Menten model-based fitting curve and (b) the sensitivity of a soft glucose sensor according to one embodiment of the present invention.

[0148] Referring to FIG. 16(a), the calibration curve of a soft glucose sensor using a Michaelis-Menten model-based fitting curve according to one embodiment of the present invention shows that the current response of the soft glucose sensor with a uniformly Au-coated AgNW / PDMS electrode extends up to 50 mM and was fitted using the Michaelis-Menten Kinetic model.

[0149] Referring to FIG. 16(b), a graph showing the sensitivity of a flexible glucose sensor according to one embodiment of the present invention is shown, in which the sensor maintains a stable detection function even after 7 days in PBS. This stability is attributed to the complete Au coating on the electrode, which enhances inertness. In addition to inertness, mechanical softness is an important property of the device. The durability of the device can be enhanced under various mechanical deformations, including bending and tension.

[0150] FIG. 17 is an optical image of a flexible glucose sensor applicable as a bioimplantable device between (a) the dermis and (b) the liver according to one embodiment of the present invention.

[0151] Referring to FIG. 17, the soft glucose sensor according to one embodiment of the present invention can demonstrate significant potential as a bioimplant solution through its key features of inertness and softness and the biocompatibility of its components. The successful conceptual demonstration of shape implantation in both (a) the dermis and (b) the liver highlights the ability of our work to solve important challenges and position it as a promising candidate for future bioimplant devices.

[0153] A method for manufacturing a flexible electrode according to the present invention comprises the steps of: preparing silver nanowires; applying liquid polydimethylsiloxane (PDMS) onto the silver nanowires to manufacture a flexible electrode; and forming a gold coating layer on the flexible electrode using a gold chloride (HAuCl4) solution containing sodium chloride (NaCl).

[0154] The method for manufacturing a soft electrode according to the present invention is a simple, effective, and reliable method for gold coating on AgNWs / PDMS electrodes, and can significantly advance the field of soft electronics, including transistors and glucose sensors. A uniform and complete Au coating can be achieved on the exposed AgNWs of the AgNWs / PDMS electrode through galvanic displacement facilitated by adding NaCl to an HAuCl4 solution. While a vigorous reaction with the HAuCl4 solution results in a non-uniform and particulate Au coating on the surface of the AgNWs, the addition of NaCl to HAuCl4 produces a uniform and complete Au coating. This is due to the principle of Le Chatelier, slow reactions resulting from changes in reduction potential, and excessive Cl. - This is achieved by preventing AgCl precipitation due to the presence of.

[0155] Uniform Au coating on AgNW / PDMS electrodes enables R with organic semiconductor in PTB7-Th-based organic transistors. C By significantly reducing , the electrical performance of such devices can be substantially improved. In addition, the R of PTB7-Th / PDMS C The development of fully flexible organic transistors with reduced density and improved flexibility suggests that our approach holds high potential for fabricating high-performance fully flexible organic electronic devices. These advancements offer advantages for application in wearable technology and bio-implantable medical systems. A proven flexible glucose sensor enhanced with a uniform and complete Au-coated AgNWs / PDMS electrode demonstrates significant electrochemical stability, which could pave the way for future bio-implantable devices.

[0157] According to one embodiment, the concentration of the chloroauric acid (HAuCl4) solution may be 0.5 mM to 5 mM, and the concentration of the sodium chloride (NaCl) in the chloroauric acid (HAuCl4) solution may be 10 mM to 200 mM.

[0158] According to one embodiment, the concentration of the chloroauric acid (HAuCl4) solution may be 0.5 mM to 5 mM; 1 mM to 5 mM; 2 mM to 5 mM; 3 mM to 5 mM; 4 mM to 5 mM; 0.5 mM to 4 mM; 0.5 mM to 3 mM; 0.5 mM to 2 mM; 0.5 mM to 1 mM; 1.5 mM to 2.5 mM; 2 mM to 3 mM; 2.5 mM to 3.5 mM; 3.0 mM to 4.0 mM; 3.5 mM to 4.5 mM.

[0159] According to one embodiment, if the concentration of the gold chloride (HAuCl4) solution is less than 0.5 mM, there may be a problem in that the portion where gold coating occurs quantitatively decreases, and the portion where gold coating does not occur on the silver nanowire increases, and if it exceeds 5 mM, an excess amount of non-reacting gold chloride is generated, which may result in a problem of reduced economic efficiency.

[0160] According to one embodiment, the concentration of sodium chloride (NaCl) in the chloroauric acid (HAuCl4) solution is 10 mM to 200 mM; 50 mM to 200 mM; 80 mM to 200 mM; 100 mM to 200 mM; 120 mM to 200 mM; 140 mM to 200 mM; 160 mM to 200 mM; 180 mM to 200 mM; 10 mM to 180 mM; 10 mM to 160 mM; 10 mM to 140 mM; 10 mM to 120 mM; 10 mM to 100 mM; 10 mM to 80 mM; 10 mM to 60 mM; 10 mM to 40 mM; 50 mM to 100 mM; 70 mM to 150 mM; 100 mM to 150 mM; It may be 120 mM to 160 mM; 150 mM to 180 mM.

[0161] According to one embodiment, if the concentration of sodium chloride (NaCl) in the chloro-gold acid (HAuCl4) solution is less than 10 mM, there may be a problem resulting in a non-uniform and granular gold coating, and if it exceeds 200 mM, there may be a problem resulting in a large amount of NaCl that is hardly involved in the reaction.

[0163] According to one embodiment, the step of forming a gold coating layer on the flexible electrode with a chloro-gold acid (HAuCl4) solution containing sodium chloride (NaCl) may induce slow galvanic displacement.

[0164] According to one embodiment, the chloroauric acid (HAuCl4) solution containing sodium chloride (NaCl) can slow down the galvanic displacement process and prevent precipitation, thereby enabling a uniform and complete Au coating on the surface of AgNWs. Excess Cl separated from NaCl - Ions can play an important role in regulating redox reactions, reducing reduction potential differences, and preventing AgCl precipitation according to Le Chatelier's principle.

[0165] The above gold coating layer has a contact resistance (R C The electrical characteristics of p-type organic transistors can be improved by significantly reducing ). In addition, high-performance fully flexible organic transistors can be developed by integrating organic semiconductor elastomer blends. A stable and mechanically stable flexible glucose sensor can be developed by utilizing a full Au coating that prevents oxidation during the glucose sensing process.

[0167] According to one embodiment, the method may further include the step of forming a gold coating layer on the flexible electrode using a chloro-gold acid (HAuCl4) solution containing sodium chloride (NaCl); and subsequently, the step of removing byproducts from the flexible electrode with the gold coating layer formed thereon using ammonia water (NH4OH).

[0168] According to one embodiment, the method may further include the step of forming a gold coating layer on the flexible electrode using a chloro-gold acid (HAuCl4) solution containing sodium chloride (NaCl); and subsequently, the step of removing byproducts from the flexible electrode with the gold coating layer formed thereon using water ammonia (NH4OH); thereby removing AgCl, which is a byproduct formed during galvanic substitution, and may be a simple method that enables uniform gold coating on the surface of silver nanowires. By developing flexible organic transistor technology using a PDMS-based flexible electrode containing uniformly gold-coated silver nanowires, Rc can be reduced and hole mobility can be significantly improved, thereby improving electrical characteristics. Furthermore, the glucose sensor developed in the present invention has a surface uniformly coated with gold, which clearly reduces the electrode oxidation effect of hydrogen peroxide (H2O2) generated during glucose detection, enabling stable operation and thus providing a glucose sensor with improved device performance and stability.

[0170] The present invention will be explained in more detail below through examples.

[0171] However, the following examples are merely for illustrating the present invention, and the content of the present invention is not limited to the following examples.

[0173] Examples

[0174] AgNWs / PDMS electrode preparation

[0175] To prepare the AgNWs / PDMS electrode, AgNWs were patterned by dropping an AgNWs solution onto a glass substrate using a polyimide tape-based shadow mask prepared with a programmable cutter (Silhouette Portrait 3) and then drying at 60 °C for 10 minutes.

[0176] Then, the shadow mask was removed from the substrate, and the patterned AgNWs were annealed at 200 °C for 20 minutes to improve conductivity. After that, a channel was formed with a razor blade to fabricate an organic transistor.

[0177] Next, degassed liquid PDMS (10:1 (w / w) prepolymer / curing agent) was applied to patterned AgNWs by spin casting at 250 rpm for 60 seconds, and then solidified at 100 °C for 1 hour.

[0178] Due to the porous nature of the AgNWs network, liquid PDMS can penetrate the pores of the network to create AgNWs that are partially embedded in the PDMS.

[0179] Then, the solidified PDMS film was carefully peeled off from the glass substrate to complete the preparation of the AgNWs / PDMS electrode.

[0181] galvanic displacement process

[0182] The exposed AgNWs of the AgNWs / PDMS electrode were coated with Au via galvanic displacement. Various C for galvanic displacement NaCl 0.5 mM HAuCl4 solutions containing (0, 10, 20, 50, 100, 200 mM) were used. The prepared solutions were dropped onto the desired areas of the AgNWs / PDMS electrode, specifically the channels, and then the samples were left at room temperature for various periods.

[0183] Then, the Au-coated AgNWs / PDMS electrode was rinsed with DI water and then soaked in NH4OH for 1 minute to remove AgCl, a byproduct formed during galvanic displacement.

[0184] Finally, the fabrication of the Au-coated AgNWs / PDMS electrode was completed by washing with DI water, then blowing off the remaining water with N2, and dehydrating at 90°C for 10 minutes.

[0186] Preparation of organic semiconductor solutions

[0187] The PTB7-Th solution was prepared by dissolving PTB7-Th in chloroform (3 mg / ml) at 80 °C for 20 minutes. The P3HT solution was prepared by dissolving P3HT in chloroform (5 mg / ml) at 60 °C for 20 minutes. The prepared PTB7-Th and P3HT solutions were used to fabricate transistors for analyzing various electrical characteristics.

[0188] To prepare a soft organic semiconductor solution, the prepared 3 mg / ml PTB7-Th solution was mixed with a liquid PDMS solution (10:1 (w / w) prepolymer / curing agent, 0.12 g / ml in chloroform) in a volume ratio of 10:1. In the resulting solution, the weight ratio of PTB7-Th to PDMS was 1:4.

[0190] Preparation of ion gel

[0191] To prepare an ion gel dielectric, PVDF-co-HFP, dehydrated EMIM-TFSI, and acetone were mixed in a weight ratio of 1:4:7 and then heated at 90 °C for 30 minutes.

[0192] The uniformly mixed solution was dropped onto a washed glass substrate and solidified in a vacuum oven at 70 °C for 12 hours. The solidified ion gel was cut into the desired shape using a razor blade.

[0194] Fabrication of organic transistors

[0195] Transistor fabrication began with preparing patterned Au-coated AgNWs / PDMS electrodes.

[0196] Then, PTB7-Th, P3HT, or PTB7-Th / PDMS was patterned by spin casting (1500 rpm, 30 sec) to the channel area of ​​the electrode using a polyimide film-based shadow mask, and then the sample was annealed at 120 °C for 20 minutes.

[0197] The retention time of the solution on the substrate prior to spin casting does not exceed 1 second, thereby preventing the substrate from swelling due to the solvent, chloroform. This short retention time, combined with the high volatility of chloroform and the fast spin speed, ensures the formation of a high-quality semiconductor film.

[0198] Then, the device fabrication was completed by stacking the prepared ion gel on top of the organic semiconductor and the gate electrode.

[0200] Glucose Sensor Fabrication

[0201] The fabrication of the glucose sensor began with preparing the patterned electrode, Au-coated AgNW / PDMS, using a HAuCl4 solution containing NaCl for a uniform Au coating.

[0202] Subsequently, a pre-prepared solution of glucose oxidase (GOD) at a concentration of 10 mg / ml in PBS was carefully applied to the working electrode. To immobilize GOD on the electrode, the working electrode area was continuously exposed to titanium isopropoxide solution vapor for 8 hours at room temperature. After this immobilization step, the sensor was thoroughly rinsed with ultrapure water to complete the fabrication process. The resulting glucose sensor was then stored in PBS at 4 °C both before and after characterization. This storage protocol ensures the stability and readiness of the sensor for subsequent analysis procedures.

[0204] Although embodiments have been described as above, those skilled in the art can apply various technical modifications and variations based on the above. For example, suitable results can be achieved even if the described techniques are performed in a different order than described, and / or the components of the described system, structure, device, circuit, etc. are combined or assembled in a form different from described, or replaced or substituted by other components or equivalents.

[0205] Therefore, other implementations, other embodiments, and equivalents to the claims also fall within the scope of the claims set forth below.

Claims

Claim 1 delete Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 delete Claim 6 delete Claim 7 delete Claim 8 delete Claim 9 delete Claim 10 delete Claim 11 delete Claim 12 A method for manufacturing a flexible electrode comprising: a step of preparing silver nanowires; a step of manufacturing a flexible electrode by applying liquid polydimethylsiloxane (PDMS) onto the silver nanowires; and a step of forming a gold coating layer on the flexible electrode using a chloro-gold acid (HAuCl4) solution containing sodium chloride (NaCl), wherein the concentration of the chloro-gold acid (HAuCl4) solution is 0.5 mM to 5 mM and the concentration of the sodium chloride (NaCl) in the chloro-gold acid (HAuCl4) solution is 10 mM to 200 mM. Claim 13 delete Claim 14 A method for manufacturing a flexible electrode according to claim 12, wherein the step of forming a gold coating layer on the flexible electrode with a chloro-gold acid (HAuCl4) solution containing sodium chloride (NaCl) induces slow galvanic displacement. Claim 15 A method for manufacturing a flexible electrode according to claim 12, further comprising the step of forming a gold coating layer on the flexible electrode using a chloro-gold acid (HAuCl4) solution containing sodium chloride (NaCl); and subsequently, the step of removing byproducts from the flexible electrode with the gold coating layer formed thereon using ammonia water (NH4OH).

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