Cell chip and method for modifying electrode surface

Abstract

The present invention relates to a cell chip for measuring local field potential (LFP), the chip comprising: an electrode array in which a reference electrode and a plurality of working electrodes are spaced apart from each other; transmission lines connected to respective electrodes; and a terminal pad part, wherein the surface of each working electrode is modified with a conductive nanomaterial to reduce interfacial impedance and improve sensitivity to electrical signals.

Description

Cell chip and electrode surface modification method

[0001] The present invention relates to a cell chip and a method for modifying the surface of an electrode.

[0002] Techniques for precisely measuring Local Field Potential (LFP) signals generated from neurons and myocardial cells are becoming increasingly important in fields such as neuroscience, cardiac physiology, and drug response analysis. In particular, electrophysiological measurement techniques based on Multi-Electrode Arrays (MEAs) are widely utilized because they can obtain high-resolution signals non-invasively at the cellular level.

[0003] However, conventional MEA electrode structures have the following technical limitations.

[0004] First, as the electrode diameter decreases, the impedance increases, which raises the noise level (RMS noise) and causes difficulties in measuring LFP, a faint signal.

[0005] Second, if the electrode diameter is large, electrical signals generated from multiple cells are averaged, making it difficult to accurately distinguish individual cell signals and thus making precise measurement impossible.

[0006] To address these issues, a technology that increases the effective surface area of ​​an electrode and reduces impedance by forming a conductive polymer or nanostructure-based modification layer on the electrode surface has recently been attracting attention. This electrode surface modification technology can improve the reliability and precision of LFP measurements by improving factors such as thermal noise, parasitic capacitance, and constant phase element (CPE).

[0007] The purpose of the present invention is to provide cell chip technology for local field potential measurement capable of reducing signal noise and analyzing precise electrical responses.

[0008] The technical problems of the present invention are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by a person skilled in the art from the description below.

[0009] A cell chip according to one embodiment of the present invention comprises: a well having a receiving portion having an open top portion capable of receiving cells and a culture medium; and a substrate disposed below the well and having an electrode pad formed thereon; wherein the electrode pad is formed on the substrate and comprises an electrode array including a plurality of working electrodes disposed to correspond to the well and a reference electrode disposed spaced apart from the working electrode; a transmission line electrically connected to the working electrode and the reference electrode, respectively; and a terminal pad portion including a terminal pad for the working electrode connected to the transmission line of the working electrode and a terminal pad for the reference electrode connected to the transmission line of the reference electrode; wherein the surface of the working electrode is exposed to the outside and a conductive nanomaterial may be deposited thereon.

[0010] The above conductive nanomaterial can be deposited by an electrochemical deposition method such as electrodeposition or electropolymerization.

[0011] The conductive nanomaterial may include any one of gold nanoparticles (Au nanoparticles, AuNPs), quantum dots (QD), reduced graphene oxide (rGO), poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS), polyaniline (PANI), carbon nanotubes (CNT), multi-walled carbon nanotubes (MWCNT), and combinations thereof.

[0012] The diameter of the above working electrode may be 100 μm or less.

[0013] The above-mentioned operating electrodes may be spaced apart in a matrix form with respect to the center, the above-mentioned reference electrodes may be arranged in a U-shape or U-shape to surround the above-mentioned operating electrodes, and the above-mentioned transmission lines may be arranged to correspond to each of the above-mentioned operating electrodes and to converge toward the center where the above-mentioned operating electrodes are arranged.

[0014] The above-mentioned operating electrodes may be spaced apart in a matrix form with respect to the center, and the reference electrodes may be arranged in a U-shape and a U-shape on the upper and lower sides of the plurality of operating electrodes, respectively, to surround the operating electrodes, and the transmission lines may be arranged to correspond to each of the operating electrodes and extend parallel to the left and right directions from the center where the operating electrodes are arranged.

[0015] The electrode array may further include a cell induction guide formed between the working electrode and the reference electrode.

[0016] A method for modifying the surface of an electrode according to one embodiment of the present invention comprises: an electrode array including an operating electrode with a surface exposed to the outside and a reference electrode spaced apart from the operating electrode; a transmission line electrically connected to the operating electrode and the reference electrode, respectively; and a terminal pad section including a terminal pad for the operating electrode connected to the transmission line of the operating electrode and a terminal pad for the reference electrode connected to the transmission line of the reference electrode; wherein the method comprises the steps of: preparing a deposition reagent including a conductive nanomaterial and one or more dispersion media (S100); removing microbubbles by applying ultrasound to the deposition reagent (S200); uniformly applying the deposition reagent onto the operating electrode (S300); and connecting an electrochemical measurement system to the terminal pad for the operating electrode and the terminal pad for the reference electrode, and performing electrochemical deposition by applying current or voltage (S400).

[0017] The above electrochemical deposition can be performed by an electrodeposition or electropolymerization method.

[0018] The conductive nanomaterial may include any one of gold nanoparticles (Au nanoparticles, AuNPs), quantum dots (QD), reduced graphene oxide (rGO), poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS), polyaniline (PANI), carbon nanotubes (CNT), multi-walled carbon nanotubes (MWCNT), and combinations thereof.

[0019] The above dispersion medium may include any one polar solvent selected from dimethyl sulfoxide (DMSO), isopropyl alcohol (IPA), ethylene glycol (EG), polyethylene glycol (PEG), and combinations thereof; or an electrolyte solution.

[0020] The cell chip for measuring local field potential according to the present invention, having the above-described configuration, can reduce interfacial impedance and improve signal sensitivity by modifying the surface of the working electrode with nanomaterials, and has the effect of enabling precise and uniform deposition in a specific area of ​​the electrode by modifying the working electrode using an electrodeposition method.

[0021] In addition, the electrode surface modification method of the present invention enables simultaneous surface modification for multiple electrodes, thereby significantly improving the reproducibility and efficiency of the manufacturing process.

[0022] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by a person skilled in the art from the description below.

[0023] FIG. 1 is a perspective view of a cell chip according to one embodiment of the present invention.

[0024] Figure 2 is an enlarged view of the electrode array of Figure 1.

[0025] Figure 3 is an enlarged view of the terminal pad portion of Figure 1.

[0026] FIG. 4 is a perspective view of a cell chip according to another embodiment of the present invention.

[0027] Figure 5 is an enlarged view of the electrode array of Figure 4.

[0028] Figure 6 is an enlarged view of the terminal pad portion of Figure 4.

[0029] FIG. 7 is a flowchart of an electrode surface modification method according to one embodiment of the present invention.

[0030] FIG. 8 is a micrograph of the surface of a working electrode whose surface has been modified by a conductive nanomaterial according to an example of the present invention.

[0031] FIG. 9 is a micrograph showing an example of a defect occurring during the manufacturing process of a working electrode whose surface is modified by a conductive nanomaterial according to an example of the present invention.

[0032] FIG. 10 shows the results of electrochemical measurements of a cell chip according to an example of the present invention, (a, c) the results of cyclic voltammetry (CV) and chronoamperometry (CA), respectively, using a cell chip with an unmodified electrode surface, and (b, d) the results of measurements taken in the same manner using a cell chip with an electrode surface modified with a conductive nanomaterial.

[0033] FIGS. 11 and 12 are local field potential measurement results (Fig. 11) and impedance measurement results (Fig. 12) measured using (a) a cell chip with its surface modified by a conductive nanomaterial and (b) a cell chip with its surface not modified, according to an example of the present invention.

[0034] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the attached drawings. However, the present invention is not limited to the embodiments disclosed below but can be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0035] Unless otherwise defined, all terms used herein (including technical and scientific terms) may be used in a meaning commonly understood by those skilled in the art to which the present invention pertains. Furthermore, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise. The terms used herein are for describing embodiments and are not intended to limit the present invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text.

[0036] As used in the specification, "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components, steps, actions, and / or elements to the mentioned components, steps, actions, and / or elements.

[0037]

[0038] FIG. 1 is a perspective view of a cell chip according to one embodiment of the present invention, FIG. 2 is an enlarged view of the electrode array of FIG. 1, and FIG. 3 is an enlarged view of the terminal pad portion of FIG. 1.

[0039] Referring to FIGS. 1 to 3, a cell chip (1) according to one embodiment of the present invention includes a well (10) having a receiving portion (100) that is open at the top and can accommodate cells and culture medium, and a substrate (20) disposed at the bottom of the well (10) and having an electrode pad (200) formed thereon.

[0040] The well (10) is configured for culturing cells or processing cultured cells, and is preferably made of a transparent biocompatible material. The biocompatible material may be a transparent plastic such as PDMS, PMMA, PET, or PC, but is not limited thereto and may be made of transparent glass, etc.

[0041] The well (10) has a receiving portion (100) that can accommodate cells and culture medium, with the top open by a partition (110). The cross-section of the receiving portion (100) can be formed in various shapes, such as a circle or a square. Meanwhile, although only the well (10) is shown in FIG. 1 for convenience of explanation, it can be formed integrally on a plate (not shown).

[0042] The substrate (20) supports the well (10) and simultaneously performs the function of exchanging electrical signals with a cell electrical signal measurement module (not shown). The substrate (20) uses a non-conductive material, and it is preferable that it be a transparent material such as glass or plastic to optically monitor the cell culture or cell processing status.

[0043] Meanwhile, the substrate (20) can also serve as a ground layer in the electrode surface modification process described later.

[0044] An electrode pad (200) may be formed on one surface of the substrate (20), and the electrode pad (200) may include an electrode array (210), a transmission line (220), and a terminal pad portion (230). For example, the electrode array (210), the transmission line (220), and the terminal pad portion (230) may be formed by depositing a transparent metal oxide, such as ITO (indium tin oxide), IZO (indium zinc oxide), ZnO (zinc oxide), or ITZO (indium thin zinc oxide), onto the substrate (20) and then patterning, or by depositing a transparent metal oxide and a photoresist together and then etching, or by a laser patterning method. In this case, the well (10), the substrate (20), and the electrode array (210), transmission line (220), and terminal pad portion (230) formed on the substrate (20) are all formed from a transparent material, which has an advantageous effect for optically monitoring the cell culture or cell processing status. As another example, the electrode array (210), transmission line (220), and terminal pad portion (230) can be formed by printing metal nanowires, which are biocompatible materials such as chromium (Cr), gold (Au), and palladium (Pd), onto a substrate (20). In this case, compared to forming the electrode array (210), transmission line (220), and terminal pad portion (230) all from a transparent material, there is an effect of improved productivity and cost-effectiveness.

[0045] The electrode array (210) includes an operating electrode (211) and a reference electrode (212) spaced apart from the operating electrode (211).

[0046] The operating electrodes (211) may be arranged adjacently in rows (horizontal direction) and columns (vertical direction) or spaced apart. In one embodiment of the present invention, the operating electrodes (212) are arranged in a matrix form with a total of 16 electrodes, but are not limited thereto and may be arranged in various numbers such as 4, 6, 7, 12, 24, 48, 96, 128, etc.

[0047] In the cell chip (1) of the present invention, the surface of the working electrode (211) is exposed to the outside and a conductive nanomaterial is deposited. At this time, the conductive nanomaterial may include any one of gold nanoparticles (Au nanoparticles, AuNPs), quantum dot (QD) reduced graphene oxide (rGO), poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS), polyaniline (PANI), carbon nanotube (CNT), multi-walled carbon nanotube (MWCNT), and combinations thereof.

[0048] At this time, it is preferable that the conductive nanomaterial be deposited by an electrochemical deposition method such as electrodeposition or electropolymerization, and the method of depositing the conductive nanomaterial on the surface of the working electrode (212) will be described later.

[0049] To increase the precision of the Local Field Potential (LFP) measurement, it is preferable that the working electrode (211) has a diameter of 500 μm or less, specifically 100 μm. The smaller the diameter of the working electrode (211), the more clearly fine electrical signals generated in a single cell or a small group of cells can be separated and detected, and the averaging or cancellation phenomena between signals can be minimized, which is advantageous in terms of spatial resolution. However, although the interfacial impedance may increase due to the miniaturization of the working electrode (211), the interfacial impedance can be effectively reduced by depositing a conductive nanomaterial on the surface of the working electrode (211) exposed to the outside, thereby simultaneously ensuring signal sensitivity, precision, and measurement reliability.

[0050] The reference electrode (212) is spaced apart from the operating electrode (211), and, for example, the reference electrode (212) may be arranged in a U-shape or a U-shape to surround a plurality of operating electrodes (211) spaced apart in a matrix shape with respect to the center.

[0051] Additionally, the reference electrode (212) and the operating electrode (211) are electrically connected to a signal amplifier (not shown) via a transmission line (220) to measure the local field potential (LFP) between the operating electrode (211) and the reference electrode (212).

[0052] The transmission line (220) serves to connect the electrode array (210) and the terminal pad portion (230), and more specifically, the transmission line (220) electrically connects the operating electrode (211) and the terminal pad (231) for the operating electrode and the reference electrode (212) and the terminal pad (232) for the reference electrode, respectively.

[0053] Meanwhile, the transmission line (220) can be formed with different widths to be connected to the terminal pad portion (230) in consideration of the coupling and parasitic capacitance generated by the adjacent transmission line (220), and can be formed with different spacing from the adjacent transmission line (220) depending on the distance from the terminal pad portion (230).

[0054] Additionally, the width of the transmission line (220) can be designed to be 1 / 2 to 1 / 5 of the diameter of the working electrode to more stably detect the electrophysiological signal of the cell and to prevent burning caused by excessive current density during electrodeposition. For example, if the diameter of the working electrode is 100 μm, the diameter of the transmission line can be about 20 to 50 μm. Also, to reduce signal noise that may be caused by interference between transmission lines (220) and parasitic capacitance, an offset gap of 10 to 100 μm is formed around the transmission line, a plane ground layer is placed in the other area, and the area outside the electrode array (210) and terminal pad portion (220) can be finished with an insulating layer.

[0055] The fine electrode array (210) with the above-described structure is configured with a fixed wiring structure that does not have a separate active element or near-field amplifier built in, and since it performs measurement functions through connection with an external system, a separate power supply is unnecessary. In addition, since direct wiring access is possible to all electrodes, it is easy to manufacture, and the high degree of freedom in selecting substrate and electrode materials makes it advantageous for integration with various application technologies, such as surface modification and the addition of sensor functions.

[0056] The terminal pad portion (230) includes a terminal pad (231) for an operating electrode and a terminal pad (232) for a reference electrode, and as described above, the terminal pad (231) for the operating electrode is connected to the operating electrode (211) through a transmission line (220), and the terminal pad (232) for the reference electrode is connected to the reference electrode (212) through a transmission line (220).

[0057] Meanwhile, the terminal pad portion (230) may be connected to an electrochemical measurement system (not shown) outside the cell chip (1) to perform the role of applying current or voltage required for electrode surface modification described later, or connected to a cell analysis system (not shown) to perform the role of transmitting cell electrical signals, such as local field potential measured in the electrode array (210).

[0058] Additionally, the cell chip (1) of the present invention may further include a seeding spot guide (240) formed between the working electrode (211) and the reference electrode (212) in the electrode array (210). At this time, the seeding spot guide (240) may be formed on the substrate (200) and serves to form a physical boundary so that the solution introduced onto the working electrode (211) of the well (100) does not reach the reference electrode (212).

[0059] FIG. 4 is a perspective view of a cell chip according to another embodiment of the present invention, FIG. 5 is an enlarged view of the electrode array of FIG. 4, and FIG. 6 is an enlarged view of the terminal pad portion of FIG. 4.

[0060] Referring to FIGS. 4 to 6, the electrode array (210) of the cell chip (1) according to another embodiment of the present invention is identical to the cell chip (1) of FIGS. 1 to 3 except that it includes a plurality of working electrodes (211) spaced apart in a matrix shape with respect to the center and reference electrodes (212) arranged in a U-shape and a U-shape respectively on the upper and lower sides of the plurality of working electrodes (211). Therefore, the description of the redundant configuration is omitted for the sake of brevity in the specification.

[0061] In particular, the two structures of the cell chip (1) according to the present invention each provide different technical features and advantages. The structure of the cell chip (1) shown in FIGS. 1 to 3 has a U-shaped or U-shaped arrangement structure in which a reference electrode surrounds the outer edge of the working electrode. This shape allows for more stable detection of the relative potential of the local field potential (LFP) generated from the target cell, which is advantageous for improving the precision and repeatability of LFP measurement. Meanwhile, the structure of the cell chip (1) shown in FIGS. 4 to 6 is designed such that the working electrode is arranged in a matrix form in the central region and its transmission line extends in the left-right direction, making it easy to precisely control the width and spacing of the transmission line of the working electrode. Accordingly, parasitic capacitance and thermal noise caused by interference between transmission lines can be reduced, enabling the acquisition of high-quality biological signals. Furthermore, it can provide structural flexibility that allows the arrangement shape and density of the working electrode to be flexibly designed according to the situation.

[0062]

[0063] FIG. 7 is a flowchart of an electrode surface modification method according to one embodiment of the present invention.

[0064] Hereinafter, with reference to FIG. 7, a method for depositing a conductive nanomaterial on the surface of the working electrode (211) will be described in detail.

[0065] A method for modifying the electrode surface according to one embodiment of the present invention specifically means modifying the surface of the working electrode (211) by depositing a conductive nanomaterial, which can contribute to improving the precision and reproducibility of local field potential measurement by improving the detection sensitivity and interface response stability of the local field potential signal, lowering the interface impedance, and improving the signal-to-noise ratio (SNR).

[0066] First, a step of preparing a deposition reagent containing a conductive nanomaterial is performed (S100). At this time, the deposition reagent is prepared by mixing the conductive nanomaterial with one or more dispersion media.

[0067] The conductive nanomaterial may include, for example, any one of gold nanoparticles (Au nanoparticles, AuNPs), quantum dots (QD), reduced graphene oxide (rGO), poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS), polyaniline (PANI), carbon nanotubes (CNT), multi-walled carbon nanotubes (MWCNT), and combinations thereof. In this case, it is preferable that the nanomaterial be a polymeric conductive material, and if it is a polymeric conductive material, it is not limited to the nanomaterials exemplified above.

[0068] The dispersion medium may be a polar solvent or an electrolyte solution. In this case, the polar solvent may be any one selected from dimethyl sulfoxide (DMSO), isopropyl alcohol (IPA), ethylene glycol (EG), polyethylene glycol (PEG), and combinations thereof. Additionally, the electrolyte solution may be an electrolyte solution comprising phosphate-buffered saline (PBS) or an aqueous sodium chloride (NaCl) solution.

[0069] Polymer-based conductive nanomaterials often possess physically and chemically sensitive bonding structures; therefore, the selection of inappropriate dispersion media or the application of inappropriate composition ratios can significantly impact the surface modification quality of cell chip electrodes, leading to issues such as reduced conductivity, interfacial instability, and damage to polymer structures. In particular, this can result not only in the loss of electrical properties at the electrode surface but also in mechanical defects such as delamination, cracking, and reduced flexibility, ultimately causing a significant decline in the uniformity and reproducibility of the electrode modification.

[0070] Accordingly, the type and mixing ratio of the dispersion medium are determined by considering compatibility with the conductive nanomaterial, improvement of interfacial bonding strength, and securing dispersion stability, and the total volume of the deposition reagent is prepared at approximately 50 mL.

[0071] Next, a step (S200) of removing microbubbles by applying ultrasound to the deposition reagent and a step (S300) of uniformly applying the deposition reagent onto the working electrode are performed.

[0072] The above deposition reagent is prepared into a homogeneous solution state by removing internal aggregates and microbubbles through ultrasonic treatment for a certain period of time, e.g., 15 minutes, while heated to 50°C or lower, preferably about 40°C. After dropping the deposition reagent onto the working electrode (211), the presence of bubbles is checked through a microscope. If bubbles are observed, they are removed by pipetting or ultrasonic application. Once all bubbles are removed, about 100 μL of the deposition reagent is uniformly applied and stabilized at room temperature.

[0073] Finally, a step (S400) is performed in which an electrochemical measurement system is connected to the terminal pad for the working electrode and the terminal pad for the reference electrode, and current or voltage is applied to perform electrochemical deposition.

[0074] The method of modifying the electrode surface by depositing a conductive nanomaterial on the surface of the working electrode (211) can be performed through an electrochemical-based deposition method such as electrodeposition or electropolymerization.

[0075] In this case, electrochemical deposition is performed using an electrochemical measurement system, and the reference electrode (CE) and the working electrode (WE) are each connected to the corresponding ports of the electrochemical measurement system. To prevent current overload, the current limit range is set from 100 nA to 500 μA, and an Ag / AgCl electrode is used as the reference electrode if necessary. Electrodeposition can be performed in chronoamperometry (CA) mode, cyclic voltammetry (CV) mode, or pulsed amperometry (PA) mode. These methods allow for the precise deposition of nanomaterials only on specific regions of the electrode by applying current or voltage; they enable localized modification of the microelectrode surface of tens of micrometers or less, and offer excellent mechanical and chemical durability, making them advantageous for ensuring long-term stability. Furthermore, the electrodeposition method allows for simultaneous deposition on multiple electrodes, such as 16 or 32, with simple settings, and enables the stable performance of the desired electrochemical coating in a short period of time.

[0076] In addition, when performing electrodeposition, the current is generally measured within the range of -1 μA to -10 μA, and there should be no abnormal oscillations in the current waveform. After deposition, the electrode surface is washed twice with distilled water or the like, and the presence and uniformity of the deposition are primarily confirmed through microscopic observation. This deposition process may be repeated four times to ensure stable electrode surface modification.

[0077] On the other hand, conventional methods such as spin coating, pad printing, screen printing, and dispensing are methods that coat a material uniformly over the entire electrode surface, making it difficult to achieve precise localized coating in fine pattern areas, such as those with a diameter of 100 μm or less. Additionally, depending on the solvent evaporation or curing process, a separate thermal curing process may be required, and there are disadvantages such as variations in coating thickness and uniformity.

[0078] In this way, by depositing the conductive nanomaterial on the surface of the externally exposed working electrode (211), the interfacial impedance of the working electrode (211) is lowered, and the sensitivity and accuracy of the electrical impedance measurement can be further improved.

[0079] FIG. 8 is a micrograph of the surface of a working electrode whose surface has been modified by a conductive nanomaterial according to an example of the present invention.

[0080] Referring to Fig. 8, the central image is an optical microscope (low magnification) photograph of the entire modified working electrode, and the bottom left and right images are photographs of two different regions of the modified working electrode, respectively, magnified 400 times. The left image shows the outer edge of the electrode, and the right image shows the center of the electrode, and it can be confirmed that conductive nanomaterials are uniformly coated in both regions. It can be confirmed that the deposited nanomaterials have uniformity across the entire surface of the electrode without clumping or concentration variations.

[0081] FIG. 9 is a micrograph showing an example of a defect occurring during the manufacturing process of a working electrode whose surface is modified by a conductive nanomaterial according to an example of the present invention.

[0082] Referring to Fig. 9, the image on the left shows an electrode array area containing multiple working electrodes, and the image on the right is a photograph of one of the defective electrodes magnified 400 times. According to the magnified image on the right, traces of nanomaterials being unevenly deposited at the center or edges of the electrode surface, or partially peeled or shrunken, can be observed. Such defects can lead to increased signal deviation between electrodes, impedance imbalance, and reduced accuracy of LFP measurements.

[0083] FIG. 10 shows the results of electrochemical measurements of a cell chip according to an example of the present invention, (a, c) the results of cyclic voltammetry (CV) and chronoamperometry (CA), respectively, using a cell chip with an unmodified electrode surface, and (b, d) the results of measurements taken in the same manner using a cell chip with an electrode surface modified with a conductive nanomaterial.

[0084] In the non-modified electrode of Fig. 10(a), the current increases linearly or shows an unstable pattern with increasing voltage, and since no oxidation-reduction peaks characteristic of electrochemical reactions appear, it can be confirmed that the deposition failed. Fig. 10(c) also shows that the change in current is irregular and does not reach a distinct equilibrium state, confirming that a stable interfacial reaction did not occur.

[0085] In contrast, in Fig. 10(b), distinct oxidation and reduction peaks are observed when the electrode surface is modified, indicating that the nanomaterial was evenly deposited at the electrode interface, leading to active electrochemical reactions. Additionally, in the time-current response of Fig. 10(d), the current converges to a stable saturation state after a certain period, indicating that the reproducibility and stability of the interfacial reaction have been secured. Thus, it can be confirmed that modifying the electrode surface with conductive nanomaterials significantly enhances electrochemical reactivity and improves the sensitivity and stability of electrical signals. Furthermore, as the capacitance at the electrode interface remains constant, the current response in the time-current method stabilizes, and reaction delays or signal distortions caused by capacitance are effectively suppressed, demonstrating that highly reliable signal measurement is possible.

[0086] FIGS. 11 and 12 are local field potential measurement results (Fig. 11) and impedance measurement results (Fig. 12) measured using (a) a cell chip with its surface modified by a conductive nanomaterial and (b) a cell chip with its surface not modified, according to an example of the present invention.

[0087] Referring to FIGS. 11 and 12, it can be seen that when the surface of the working electrode is modified with a conductive nanomaterial, the average voltage level of the measured LFP signal is stable and noise is significantly reduced compared to the case where it is not modified. This is a result of reduced impedance at the electrode interface and reduced thermal noise. Furthermore, when a cell chip with a working electrode surface modified with a conductive nanomaterial is used, the electrode interface impedance shows a reduction in impedance of about 80% compared to an electrode without surface modification, and it can be seen that low electrode interface impedance is maintained across the entire frequency range. On the other hand, it can be seen that a cell chip without surface modification exhibits high impedance at the level of tens of MΩ across the entire frequency range, which directly leads to signal loss and increased noise in LFP measurement.

[0088]

[0089] Although embodiments of the present invention have been described above with reference to the attached drawings, those skilled in the art will understand that the present invention may be implemented in other specific forms without changing its technical concept or essential features. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

[0090] 1: Cell chip

[0091] 10: Well

[0092] 100: Reception Department

[0093] 110: Bulkhead

[0094] 20: Substrate

[0095] 200: Electrode pad

[0096] 210: Electrode array

[0097] 211: Working electrode

[0098] 212: Reference electrode

[0099] 220: Transmission line

[0100] 230: Terminal pad section

[0101] 231: Terminal pad for operating electrode

[0102] 232: Terminal pad for reference electrode

[0103] 240: Cell Induction Guide

Claims

1. A well having a receiving portion that is open at the top and can accommodate cells and culture medium; and A substrate disposed at the lower part of the well and having an electrode pad formed thereon; comprising The electrode pad comprises: an electrode array formed on the substrate and including a plurality of working electrodes arranged to correspond to the well and a reference electrode arranged spaced apart from the working electrodes; a transmission line electrically connected to the working electrodes and the reference electrodes, respectively; and a terminal pad section including a terminal pad for the working electrode connected to the transmission line of the working electrode and a terminal pad for the reference electrode connected to the transmission line of the reference electrode. A cell chip having a surface of the above-mentioned working electrode exposed to the outside and a conductive nanomaterial deposited thereon.

2. In Paragraph 1, The above conductive nanomaterial is a cell chip deposited by an electrochemical deposition method of electrodeposition or electropolymerization.

3. In Paragraph 1, The above conductive nanomaterial comprises any one of gold nanoparticles (Au nanoparticles, AuNPs), quantum dots (QD), reduced graphene oxide (rGO), poly(3,4-ethylenedioxoythiophene)-polystyrene sulfonate (PEDOT:PSS), polyaniline (PANI), carbon nanotubes (CNT), multi-walled carbon nanotubes (MWCNT), and combinations thereof, in a cell chip.

4. In Paragraph 1, A cell chip having a diameter of 100 μm or less of the above-mentioned working electrode.

5. In Paragraph 1, The above-mentioned operating electrodes are spaced apart in a matrix form with respect to the center, and The above reference electrode is arranged in a U-shape or U-shape to surround the above working electrode, and A cell chip in which the transmission lines correspond to each of the operating electrodes and are arranged to converge toward the center where the operating electrodes are positioned.

6. In Paragraph 1, The above-mentioned operating electrodes are spaced apart in a matrix form with respect to the center, and The reference electrode is arranged in a U-shape and a U-shape, respectively, on the upper and lower sides of the plurality of working electrodes to surround the working electrode, and A cell chip in which the transmission lines correspond to each of the operating electrodes and are arranged to extend parallel to the left and right directions from the center where the operating electrodes are placed.

7. In Paragraph 1, The cell chip, wherein the electrode array further comprises a cell induction guide formed between the working electrode and the reference electrode.

8. An electrode array comprising an operating electrode having a surface exposed to the outside and a reference electrode spaced apart from the operating electrode; a transmission line electrically connected to the operating electrode and the reference electrode, respectively; and a terminal pad portion comprising a terminal pad for the operating electrode connected to the transmission line of the operating electrode and a terminal pad for the reference electrode connected to the transmission line of the reference electrode; wherein A step of preparing a deposition reagent including a conductive nanomaterial and one or more dispersion media (S100); A step of removing microbubbles by applying ultrasound to the deposition reagent (S200); Step of uniformly applying the deposition reagent onto the above working electrode (S300); and A method for modifying an electrode surface, comprising the step (S400) of connecting an electrochemical measurement system to the terminal pad for the working electrode and the terminal pad for the reference electrode, and applying current or voltage to perform electrochemical deposition.

9. In Paragraph 8, The above electrochemical deposition is an electrode surface modification method performed by an electrodeposition or electropolymerization method.

10. In Paragraph 8, A method for modifying an electrode surface, wherein the conductive nanomaterial comprises any one of gold nanoparticles (Au nanoparticles, AuNPs), quantum dots (QD), reduced graphene oxide (rGO), poly(3,4-ethylenedioxoythiophene)-polystyrene sulfonate (PEDOT:PSS), polyaniline (PANI), carbon nanotubes (CNT), multi-walled carbon nanotubes (MWCNT), and combinations thereof.

11. In Paragraph 8, A method for modifying an electrode surface, wherein the dispersion medium comprises any one polar solvent selected from dimethyl sulfoxide (DMSO), isopropyl alcohol (IPA), ethylene glycol (EG), polyethylene glycol (PEG), and combinations thereof; or an electrolyte solution.

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