Chemical sensor module

Abstract

To provide a chemical sensor module capable of controlling a potential of a thin specimen liquid while covering a surface of a sensor element with the specimen liquid.SOLUTION: A chemical sensor module comprises: a first chip including a first substrate having a first surface and a sensor element disposed on the first surface; a second chip including a second substrate having a second surface and a nonpolarizable electrode disposed on the second surface; and a conductive joining member electrically connected to the nonpolarizable electrode. The second surface of the second substrate faces the first surface of the first substrate in a first direction, the joining member is disposed between the first surface of the first substrate and the second surface of the second substrate and forms a gap between the first surface of the first substrate and the second surface of the second substrate, and the nonpolarizable electrode is located in the gap and faces the first surface of the first substrate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a chemical sensor module. [Background technology]

[0002] A chemical sensor has been proposed that detects target substances while the surface of graphene is covered with a liquid. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-41626 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of an embodiment of the present invention is to provide a chemical sensor module that can control the potential of a sample liquid while coating the surface of a sensor element with a thin sample liquid. [Means for solving the problem]

[0005] According to an embodiment of the present invention, a chemical sensor module comprises a first substrate having a first surface, a first chip having a sensor element arranged on the first surface, a second substrate having a second surface, a second chip having a non-polarizable electrode arranged on the second surface, and a conductive bonding member electrically connected to the non-polarizable electrode, wherein the second surface of the second substrate faces the first surface of the first substrate in a first direction, the bonding member is arranged between the first surface of the first substrate and the second surface of the second substrate, forming a gap between the first surface of the first substrate and the second surface of the second substrate, and the non-polarizable electrode is located in the gap and faces the first surface of the first substrate in the first direction. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a schematic cross-sectional view of a chemical sensor module according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram of a sensor element according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] Each embodiment will be described below with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Even when the same part is shown, the dimensions and ratios may be different depending on the drawing. Furthermore, identical or similar elements are given the same reference numerals.

[0008] As shown in FIG. 1, the chemical sensor module of the embodiment includes a first chip 100 and a second chip 200.

[0009] The first chip 100 has a first substrate 101 and a sensor element 110. The first substrate 101 has a first surface 101A. The first substrate 101 is, for example, a silicon substrate. The sensor element 110 includes, for example, graphene. The sensor element 110 is disposed on the first surface 101A of the first substrate 101. The sensor element 110 is disposed on the first surface 101A, for example, via an insulating film.

[0010] 2, the first chip 100 may further include a drain electrode 41 and a source electrode 42. The drain electrode 41 and the source electrode 42 are arranged on the first surface 101A of the first substrate 101, for example, via an insulating film (not shown). The drain electrode 41 and the source electrode 42 are electrically connected to the sensor element 110 (graphene). The sensor element 110 (graphene) is located between the drain electrode 41 and the source electrode 42, and a current (drain current) flows between the drain electrode 41 and the source electrode 42 through the sensor element 110 (graphene).

[0011] As will be described later, a sample atmosphere flows so as to come into contact with the sample liquid that coats the surface of the sensor element 110. When target molecules that may be contained in the sample atmosphere are taken up by the sample liquid and come close to the surface of the sensor element 110, the electronic state of the sensor element 110 (graphene) changes. This change can be detected as a change in drain current, making it possible to know the presence and concentration of the target molecules in the sample atmosphere.

[0012] The first chip 100 may also have a probe molecule 120 located on the surface of the sensor element 110 (graphene). The probe molecule 120 located on the surface of the sensor element 110 means that the probe molecule 120 is bound, adsorbed, or in close proximity to the surface of the sensor element 110 by chemical or charge attraction, π-π interaction, cation-π interaction, hydrophobic interaction, or the like. The probe molecule 120 includes, for example, at least one of a protein, a peptide, an antibody, a DNA aptamer, or a biomolecule derived from these. The probe molecule 120 can be located on the surface of the sensor element 110 via, for example, a linker molecule 130. For example, pyrene or the like can be used as the linker molecule 130.

[0013] The probe molecule 120 can specifically bind to or interact with a target molecule. When the probe molecule 120 binds to or interacts with the target molecule, the target molecule approaches the surface of the sensor element 110, and the electronic state of the sensor element 110 changes due to the charge of the target molecule or the structural change of the probe molecule 120 caused by binding to or interacting with the target molecule. This can be detected as a change in drain current.

[0014] As shown in FIG. 1, the second chip 200 has a second substrate 201 and a non-polarizable electrode 210. The second substrate 201 has a second surface 201A. The second surface 201A of the second substrate 201 faces the first surface 101A of the first substrate 101 in the first direction Z. The second substrate 201 is, for example, a silicon substrate. The non-polarizable electrode 210 is disposed on the second surface 201A of the second substrate 201. The non-polarizable electrode 210 is disposed on the second surface 201A, for example, via an insulating film.

[0015] The area of ​​first surface 101A of first substrate 101 is larger than the area of ​​second surface 201A of second substrate 201. The planar size of first chip 100 is larger than the planar size of second chip 200.

[0016] The chemical sensor module of the embodiment further includes a bonding member 50 disposed between the first surface 101A of the first substrate 101 and the second surface 201A of the second substrate 201. A plurality of bonding members 50 are disposed between the first surface 101A of the first substrate 101 and the second surface 201A of the second substrate 201.

[0017] The second chip 200 is provided on the first substrate 101 via a bonding member 50, with the second surface 201A facing the first surface 101A, and is so-called flip-chip mounted. The second chip 200 is arranged in an area of ​​the first surface 101A of the first substrate 101 where the sensor element 110 is not arranged. For example, the second chip 200 is arranged in an area close to the area where the sensor element 110 is arranged in the second direction X. The distance between the sensor element 110 and the second chip 200 in the second direction X can be, for example, 0.5 mm or more and 5 mm or less.

[0018] The bonding members 50 are conductive and are, for example, gold bumps. The non-polarizable electrodes 210 are electrically connected to the bonding members 50. For example, the non-polarizable electrodes 210 are electrically connected to the bonding members 50 by wiring 60 arranged on the second surface 201A of the second substrate 201 via an insulating film. The outermost surface of the wiring 60 is made of, for example, gold. The bonding members 50 are also connected to wiring arranged on the first surface 101A of the first substrate 101. The non-polarizable electrodes 210 and the sensor element 110 are electrically connected to an external circuit through the wiring arranged on the first surface 101A of the first substrate 101.

[0019] The bonding member 50 disposed between the first surface 101A of the first substrate 101 and the second surface 201A of the second substrate 201 forms a gap 10 between the first surface 101A of the first substrate 101 and the second surface 201A of the second substrate 201. That is, the thickness of the bonding member 50 disposed between the first surface 101A of the first substrate 101 and the second surface 201A of the second substrate 201 in the first direction Z is greater than the thicknesses of the non-polarizable electrode 210 and the wiring 60 in the first direction Z, forming a gap 10 between the first surface 101A of the first substrate 101 and the second surface 201A of the second substrate 201. The non-polarizable electrode 210 is located in the gap 10 and faces the first surface 101A of the first substrate 101 in the first direction Z. Non-polarizable electrode 210 is not in contact with first surface 101A, and sample liquid 90, which will be described later, is filled between non-polarizable electrode 210 and first surface 101A.

[0020] The sample liquid 90 coats the surface of the sensor element 110. A sample atmosphere is allowed to flow so as to come into contact with the sample liquid 90 that coats the surface of the sensor element 110. If the sample atmosphere contains target molecules, the target molecules in the sample atmosphere are taken up by the sample liquid 90 and come into close proximity to the surface of the sensor element 110 and the probe molecules 120. This causes a change in the electrical properties (e.g., drain current) of the sensor element 110, and the presence and concentration of the target molecules in the sample atmosphere can be detected from this change. The sample liquid 90 that coats the surface of the sensor element 110 coats the probe molecules 120. This increases the ability of the biologically derived probe molecules 120 (e.g., peptides, DNA aptamers, etc.) to capture the target molecules, thereby improving the detection sensitivity of the target molecules.

[0021] Furthermore, the sample liquid 90 covers the non-polarizable electrode 210 in the gap 10 between the first surface 101A of the first substrate 101 and the second surface 201A of the second substrate 201. The non-polarizable electrode 210 is in contact with the sample liquid 90. The non-polarizable electrode 210 has a characteristic that, when the voltage is changed, an oxidation-reduction reaction occurs on the electrode surface, causing a current to flow. This characteristic allows the potential difference between the non-polarizable electrode 210 and the sample liquid 90 to be kept constant, and the potential of the sample liquid 90 can be controlled or stabilized by an external power source. The non-polarizable electrode 210 can be, for example, a silver-silver chloride electrode, a hydrogen electrode, a calomel electrode, or the like. The silver-silver chloride electrode is preferable because it has a simple configuration, can be miniaturized, and has a small environmental impact.

[0022] For example, the sample solution 90 contains chloride ions, and the non-polarizable electrode 210 is a silver-silver chloride electrode having silver chloride on its surface. The silver-silver chloride electrode (non-polarizable electrode 210) comes into contact with the sample solution 90 containing chloride ions, and an oxidation-reduction reaction occurs, thereby applying a potential to the sample solution 90. This stabilizes the potential of the sample solution 90, reducing noise in the drain current of the sensor element 110. The potential of the sample solution 90 is controlled to a constant potential difference with respect to the potential of the silver-silver chloride electrode according to the Nernst equation. The oxidation-reduction reaction with silver chloride (AgCl) (AgCl + e - → Ag + Cl - ) to measure the chloride ions (Cl - ) moves between the sample solution 90 and the surface of the silver-silver chloride electrode until the potential of the sample solution 90 stabilizes.

[0023] The chemical sensor module of the embodiment may further include a sample liquid supply section 400 and a water-absorbent member 300.

[0024] Sample liquid supply unit 400 supplies sample liquid 90 to side surface 201C of second substrate 201 of second chip 200. Sample liquid supply unit 400 is, for example, a nozzle that supplies sample liquid 90 using a dispenser or an inkjet method.

[0025] Sample liquid 90 supplied to side surface 201C of second substrate 201 moves from first surface 101A located below side surface 201C to gap 10 by capillary action. The size of gap 10 in first direction Z is, for example, 10 μm or more and 100 μm or less. This ensures that non-polarizable electrode 210 located in gap 10 is covered with sample liquid 90. Sample liquid 90 supplied to side surface 201C of second substrate 201 forms a fillet 90A on side surface 201C. Once fillet 90A is formed, sample liquid 90 may be supplied to fillet 90A from sample liquid supply unit 400.

[0026] Sensor element 110 is located between second chip 200 and water-absorbent member 300 in second direction X. Second chip 200 is located between sample liquid supply unit 400 and sensor element 110 in second direction X. Side 201C of second substrate 201, to which sample liquid 90 is supplied, is located on the opposite side in second direction X to side 201D of second substrate 201 that is close to sensor element 110.

[0027] The sample liquid 90 leaking from the gap 10 flows into the region where the sensor element 110 is disposed, and covers the surface of the sensor element 110. The sample liquid 90 that covers the non-polarizable electrode 210 in the gap 10 and the surface of the sensor element 110 spreads continuously in the first direction X over the first surface 101A of the first substrate 101.

[0028] The water-absorbent member 300 is disposed on the first surface 101A of the first substrate 101 and comes into contact with the sample liquid 90. The water-absorbent member 300 is, for example, a nonwoven fabric that has water-absorbency to the sample liquid 90.

[0029] As the sample liquid 90 is supplied from the sample liquid supply section 400, the absorbent member 300 absorbs the sample liquid 90, and a slow flow of the sample liquid 90 is formed from the side surface 201C or fillet 90A of the second substrate 201 to which the sample liquid 90 is supplied, through the gap 10 and the sensor element 110, to the absorbent member 300.

[0030] When sample liquid 90 accumulates in water-absorbent member 300 and the water-absorbing power of water-absorbent member 300 decreases, water-absorbent member 300 can be replaced. Also, the parts themselves, including first tip 100 and second tip 200 joined to first tip 100 by joining member 50, can be replaced.

[0031] When the thickness (thickness in the first direction Z) of the sample liquid 90 covering the surface of the sensor element 110 is thin, the target molecules in the sample atmosphere taken up by the sample liquid 90 are more likely to come close to the surface of the sensor element 110 and the probe molecules 120, and the change in concentration of the target molecules in the sample liquid 90 is greater, thereby improving the detection sensitivity of the target molecules.

[0032] Because water has a high surface tension, it tends to form beads on the surface of the sensor element 110, increasing the thickness of the sample liquid on the surface of the sensor element 110. Furthermore, such beads of water tend to be absorbed the moment they come into contact with the nonwoven fabric, making it difficult to constantly maintain a thin sample liquid on the surface of the sensor element 110.

[0033] Therefore, it is preferable to use an organic solvent such as dimethyl sulfoxide (DMSO), dimethylformamide (DMF), or N-methyl-2-pyrrolidone (NMP), which has a surface tension lower than that of water, as the sample liquid 90. These organic solvents can spread thinly over the surface of the sensor element 110, thereby improving the detection sensitivity of the target molecule. Furthermore, even if the organic solvent comes into contact with the nonwoven fabric, it can remain thinly on the surface of the sensor element 110. The thickness of the sample liquid 90 on the surface of the sensor element 110 is, for example, 10 μm or more and 0.5 mm or less.

[0034] Specimen liquid 90, which covers non-polarizable electrode 210 in gap 10 and also covers the surface of sensor element 110, is spread thinly and continuously in first direction X on first surface 101A of first substrate 101. Since such specimen liquid 90 is held on first surface 101A by surface tension, specimen liquid 90 is held on first surface 101A even when first surface 101A is oriented downward (in the direction of gravity).

[0035] When supplying the sample liquid 90 directly to the surface of the sensor element 110, in order to maintain a thin sample liquid 90 on the surface of the sensor element 110, the sample liquid 90 must be supplied in small, constant amounts at all times, which is difficult to control.

[0036] According to this embodiment, gap 10 and fillet between second substrate 201 and first substrate 101 function as a temporary liquid reservoir buffer for sample liquid 90, stabilizing the amount of sample liquid 90 on the surface of sensor element 110. Therefore, to prevent sample liquid 90 on first surface 101A from running out and overflowing, sample liquid 90 can be intermittently dropped onto side surface 201C or fillet 90A of second substrate 201 by, for example, an inkjet method, thereby facilitating supply control of sample liquid 90.

[0037] Furthermore, according to this embodiment, the sample liquid 90 does not connect between the surface of the sensor element 110 and the sample liquid supply unit 400, thereby reducing the backflow of sample liquid 90 contaminated by the sample atmosphere on the surface of the sensor element 110 to the upstream side. Furthermore, the non-polarizable electrode 210 is covered and protected by the sample liquid 90 in the gap 10, and therefore does not come into contact with the sample atmosphere, preventing contamination of the non-polarizable electrode 210. This allows for highly reliable detection.

[0038] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0039] 10...gap, 41...drain electrode, 42...source electrode, 50...bonding member, 90...analyte liquid, 100...first chip, 101...first substrate, 101A...first surface, 110...sensor element, 120...probe molecule, 200...second chip, 201...second substrate, 201A...second surface, 210...non-polarizable electrode, 300...water-absorbing member, 400...analyte liquid supply unit

Claims

1. a first chip having a first substrate having a first surface and a sensor element disposed on the first surface; a second chip having a second substrate having a second surface and a non-polarizable electrode disposed on the second surface; a conductive joining member electrically connected to the non-polarizable electrode; Equipped with the second surface of the second substrate faces the first surface of the first substrate in a first direction; the bonding member is disposed between the first surface of the first substrate and the second surface of the second substrate, and forms a gap between the first surface of the first substrate and the second surface of the second substrate; The non-polarizable electrode is located in the gap and faces the first surface of the first substrate in the first direction.

2. 2. The chemical sensor module according to claim 1, wherein the sample liquid covering the non-polarizable electrode in the gap and covering the surface of the sensor element is spread continuously on the first surface of the first substrate.

3. the sample liquid contains chloride ions, The chemical sensor module according to claim 2 , wherein the non-polarizable electrode is a silver-silver chloride electrode.

4. a sample liquid supply unit that supplies the sample liquid to a side surface of the second substrate; a water-absorbent member disposed on the first surface of the first substrate and having water-absorbency with respect to the sample liquid; Equipped with The chemical sensor module according to claim 2 , wherein the sensor element is located between the second chip and the water-absorbing member in a second direction perpendicular to the first direction.

5. The chemical sensor module according to claim 4 , wherein the second chip is located between the sample liquid supply unit and the sensor element in the second direction.

6. The chemical sensor module according to claim 1 , wherein the sensor element comprises graphene.

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