CN115684305A - Biological sensing device - Google Patents

Abstract

A biosensing device comprises a substrate, a plurality of metal conducting layers, a plurality of working electrodes, a counter electrode and an insulating layer. The metal conducting layers are arranged on the substrate and provided with first upper surfaces. The plurality of working electrodes and the counter electrode are arranged on the first upper surfaces of the corresponding metal conducting layers, wherein the first top surface of each working electrode is higher than the first upper surface of the metal conducting layer, and the second top surface of the counter electrode is higher than the first top surface. The insulating layer covers the metal conducting layer and surrounds the working electrode and the counter electrode, wherein the second upper surface of the insulating layer is arranged between the first top surface and the first upper surface of the metal conducting layer, so that the working electrode and the counter electrode protrude out of the second upper surface of the insulating layer. The above-described biosensing device can increase the sensing sensitivity.

Description

Biological sensing device

Technical Field

The present invention relates to a sensing device, and more particularly, to a bio-sensing device for detecting bio-molecules.

Background

In recent years, various different detection methods of biomolecules have been developed for diagnosing various diseases, conducting physiological metabolism-related studies or monitoring environmental factors, and the like. The development of Micro-electro-mechanical Systems (MEMS) is attracting attention, and a semiconductor device can be fabricated to be a microchip for sensing optical, chemical, biological molecules or other properties by combining semiconductor process technology and precision mechanical technology. However, as the semiconductor industry moves into the nanometer technology process node to seek higher device density, higher performance, and lower cost, challenges from manufacturing and design aspects drive the development of three-dimensional designs. Accordingly, there is a need to develop a biosensor chip with high performance and low cost.

Disclosure of Invention

The invention provides a biological sensing device, which comprises a plurality of protruding working electrodes and a pair of electrodes, wherein the second top surface of the pair of electrodes is higher than the first top surface of the working electrodes so as to enhance the maximum electric field value of the working electrodes and further improve the sensing sensitivity.

The biosensor device according to an embodiment of the present invention includes a substrate, a plurality of metal conductive layers, a plurality of working electrodes, a pair of electrodes, and an insulating layer. The metal conducting layers are arranged on the substrate, and each metal conducting layer is provided with a first upper surface. The plurality of working electrodes are arranged on the first upper surfaces of the corresponding metal conducting layers, wherein each working electrode comprises a first top surface, and each first top surface is higher than the first upper surface of the metal conducting layer. The counter electrode is disposed on the first upper surface of the corresponding metal conductive layer and adjacent to the plurality of working electrodes, wherein the counter electrode includes a second top surface higher than the first top surface. The insulating layer covers the metal conducting layer and surrounds the working electrodes and the counter electrodes, wherein a second upper surface of the insulating layer is arranged between the first top surfaces of the working electrodes and the first upper surface of the metal conducting layer, so that the working electrodes and the counter electrodes protrude out of the second upper surface of the insulating layer.

The purpose, technical content, features and effects of the present invention will be more readily understood by the following detailed description of the specific embodiments in conjunction with the accompanying drawings.

Drawings

Embodiments of the present invention are read in light of the following detailed description with accompanying drawings.

FIG. 1 illustrates a cross-sectional view of a biosensing assembly according to some embodiments of the present invention.

FIGS. 2-12 illustrate cross-sectional views of a bio-sensor assembly at various stages of processing, according to some embodiments of the present invention.

FIG. 13 shows a top view of a biosensing device according to some embodiments of the present invention.

FIG. 14A illustrates a cross-sectional view of a line AA of a biosensing device, according to some embodiments of the present invention.

Fig. 14B is a partially enlarged schematic view of the cross-sectional view of fig. 14A.

FIG. 15 is a cross-sectional view of a biosensing device, according to some embodiments of the present invention.

FIG. 16 is a diagram showing the arrangement of the working electrode, the counter electrode and the reference electrode of a biosensing device according to some embodiments of the present invention.

[ notation ] to show

100. Biosensing assembly

102. Base material

103. Substrate

104. A first insulating layer

105. A first upper surface

106. Metal conductive layer

107. Side wall

108. A second insulating layer

109. A first top surface

110. Working electrode

111. Side wall

112. Biological probe

113. Second upper surface

200. Biosensing assembly

202. Base material

203. Substrate

204. A first insulating layer

205. A first upper surface

206. Metal conductive layer

207. Side wall

208. Conductive layer

209. A first top surface

210. Light shield

211. Side wall

212. Working electrode

213. Second upper surface

214. Light shield

216. Layer of insulating material

218. A second insulating layer

300. Biological sensing device

302. Base material

303. Substrate

304. A first insulating layer

305. Side wall

306a metal layer

306b metal layer

307. A first upper surface

308. A second insulating layer

309. Side wall

310. Working electrode

310a, 310b, 310c working electrode

311. A first top surface

312. Counter electrode

3121. Second top surface

3122. Finger-shaped structure

312a, 312b counter electrode

313. Second upper surface

314. Biological probe

316. Signal detection unit

318. Conducting wire

319a, 319b, 319c reference electrodes

E electric field

E75 Electric field

E50 Electric field

H1 First height

H2 Second height

H3 Third height

H4 A fourth height

WEA working electrode area

Detailed Description

The invention will next be described in the context of a number of different embodiments or examples for implementing different features of the invention. The components and arrangements of specific embodiments are described below to simplify the present disclosure. These examples are given by way of illustration only and are not intended to limit the invention. For example, a first element formed "on" or "over" a second element can include the first element in direct contact with the second element in embodiments, or can include additional elements between the first element and the second element such that the first element and the second element are not in direct contact. In addition, reference numerals and/or letters may be used repeatedly in various examples of the invention. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations.

Furthermore, terms such as "below," "lower," "above," "higher," and other similar relative spatial relationships may be used herein to describe the relationship of one component or feature to another component or feature in the drawings. The relative spatial relationships are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may have other guiding ways (rotating 90 degrees or towards other directions), and the relative spatial relationship can be interpreted according to the above ways.

FIG. 1 illustrates a cross-sectional view of a biosensing assembly according to some embodiments of the present invention. As shown in fig. 1, the biosensing assembly 100 includes a substrate 103, a metal conducting layer 106, a second insulating layer 108, a plurality of working electrodes 110, and a biological probe 112. In some embodiments, the substrate 103 includes a base 102 and a first insulating layer 104. The substrate 103 may further include, but is not limited to, other semiconductor materials such as gallium nitride (GaN), silicon carbide (SiC), silicon germanium (SiGe), germanium, or combinations thereof. The substrate 102 may be, for example, a silicon substrate. The substrate 102 may comprise various doping configurations depending on design requirements in the art. In one embodiment, the substrate 102 may be a heavily doped, low resistivity semiconductor substrate. In another embodiment, the substrate 103 is a glass substrate without the first insulating layer 104.

The first insulating layer 104 is disposed on the substrate 102. In an embodiment, the first insulating layer 104 may include, but is not limited to, an oxide, a nitride, an oxynitride, or a combination thereof, such as silicon oxide, silicon nitride, silicon oxynitride. The first insulating layer 104 is made of a material with a low dielectric constant (low-K), so that the bio-sensing device 100 has good insulating properties. In some embodiments, the first insulating layer 104 has a thickness of about 0.02 microns (μm) to about 0.25 microns, such as about 0.10 microns, about 0.15 microns, or about 0.20 microns.

The metal conductive layer 106 is disposed on the substrate 103 and has a sidewall 107 and a first upper surface 105, wherein the sidewall 107 is adjacent to the first upper surface 105, and the sidewall 107 is covered by the second insulating layer 108. In an embodiment, the metal conductive layer 106 may include, but is not limited to, titanium (Ti), nickel (Ni), silver (Ag), aluminum (Al), copper aluminum alloy (AlCu), copper aluminum silicon alloy (AlSiCu), or a combination thereof. In one embodiment, the thickness of metal conductive layer 106 is about 0.02 microns to about 0.7 microns, such as about 0.1 microns, 0.2 microns, 0.3 microns, 0.4 microns, about 0.5 microns, or about 0.6 microns.

Each working electrode 110 is disposed on the first upper surface 105 of the metal conductive layer 106, and each working electrode has a first top surface 109 and a sidewall 111. Each first top surface 109 is higher than the first top surface 105 of the metal conductive layer 106, each sidewall 111 is adjacent to each first top surface 109, and the second insulating layer 108 covers only a portion of each sidewall 111. Each working electrode 110 has a first height H1 protruding above metal conductive layer 106. In some embodiments, first height H1 of each working electrode 110 is about 0.05 microns to about 1 micron, such as about 0.05 microns, 0.1 microns, 0.2 microns, about 0.3 microns, or about 0.4 microns. In some embodiments, each working electrode 110 has a width of about 0.08 microns to about 0.4 microns, such as about 0.08 microns, 0.1 microns, 0.2 microns, or about 0.3 microns. In one embodiment, each working electrode 110 has an aspect ratio (aspect ratio) of between about 0.125 and about 7.5, such as about 0.2 or about 0.3.

In some embodiments, the working electrodes 110 may be cylinders or regular polygonal cylinders, such as regular triangular cylinders, regular rectangular cylinders, regular pentagonal cylinders, regular hexagonal cylinders, or regular octagonal cylinders. In some embodiments, such working electrodes 110 may include, but are not limited to, tantalum (Ta), tantalum nitride (TaN), copper (Cu), titanium (Ti), titanium nitride (TiN), tungsten (W), titanium (Ti), nickel (Ni), silver (Ag), aluminum (Al), copper aluminum alloy (AlCu), copper aluminum silicon alloy (AlSiCu), or combinations thereof. In some embodiments, the material of the working electrodes 110 is preferably titanium nitride (TiN).

The biological probe 112 may be modified and attached to the working electrodes 110 by various well-known methods. According to various embodiments of the present invention, the biological probe 112 may include, but is not limited to, nucleic acids, cells, antibodies, enzymes, polypeptides, peptides, aptamers, saccharides, or combinations thereof. It should be noted that the biological probe 112 can distinguish various biological molecules. For example, when the biological probe 112 is an antibody, it can bind to a target molecule (i.e., antigen) in a sample and detect the presence of the target molecule by various well-known techniques.

The second insulating layer 108 covers the metal conductive layer 106 and surrounds the working electrodes 110, wherein the second upper surface 113 of the second insulating layer 108 is between the first top surfaces 109 of the working electrodes 110 and the first upper surface 105 of the metal conductive layer 106, so that the working electrodes 110 protrude from the second upper surface 113 of the second insulating layer 108. The protruding portions have a second height H2, which is a vertical distance from the first top surfaces 109 to the second top surface 113 of the second insulating layer 108. In some embodiments, the second height H2 is about 0.01 microns to about 0.55 microns, such as about 0.05 microns, 0.15 microns, about 0.3 microns, about 0.45 microns, about 0.5 microns, or about 0.6 microns. Therefore, when a voltage is applied to the working electrodes 110, the working electrodes 110 generate an electric field to surround the protruding working electrodes 110. The electric field is not limited to the first top surface 109 of the working electrodes 110, but extends to the sidewalls 111 of the working electrodes 110, so that the electrochemical reaction is greatly increased, and the signal strength is increased. Working electrode 110 with a cubic configuration provides better sensitivity than the well-known planar working electrode under the same applied voltage.

In some embodiments, the second insulating layer 108 may include, but is not limited to, an oxide, a nitride, an oxynitride, or a combination or compound thereof, such as silicon oxide, silicon nitride, silicon oxynitride. In some embodiments, the material of the first insulating layer 104 is the same as the material of the second insulating layer 108. In some embodiments, the material of the first insulating layer 104 is different from the material of the second insulating layer 108.

In addition, when a voltage is applied to the working electrode 110, background noise is generated to interfere with the detection result, and the generation of the background noise is related to the cross-sectional area of the electrode. The larger the cross-sectional area of the electrode, the higher the intensity of the background noise. According to some embodiments of the present invention, when a voltage is applied to the working electrode 110, the electric field generated by the working electrode 110 covers a larger range than a well-known planar working electrode. The coverage of the electric field is not limited to the first top surfaces 109 of the working electrodes 110, but extends to the sidewalls 111 of the working electrodes 110. The width of the working electrodes 110 can be smaller than that of the conventional planar working electrode for the same effective electric field coverage. Accordingly, the working electrode 110 according to an embodiment of the present invention may have a width smaller than that of a known planar working electrode, and thus have a cross-sectional area smaller than that of the known planar working electrode, reducing the generation of background noise.

As previously described, in certain embodiments, the first height H1 of each working electrode 110 is about 0.05 microns to about 0.6 microns. When first height H1 of each working electrode 110 is less than 0.05 microns, second height H2 of the protruding portion of each working electrode 110 will be less than 0.01 microns. In this case, when a voltage is applied to the working electrode 110, the effective electric field range is increased to a limited extent, resulting in insignificant effects of improving the electrochemical reaction of the biological probe 112. Accordingly, it can be seen that the higher the protruding portion of the working electrode 110 is, the wider the effective electric field is covered, and the better the electrochemical reaction is. It is noted that the aspect ratio of the working electrode 110 is about 0.125 to about 7.5. When the aspect ratio of the working electrode 110 is greater than 7.5, the working electrode is prone to structural defects, which reduces the reliability of the entire device.

Fig. 2-12 illustrate cross-sectional views of a method of fabricating a biosensing assembly 200 at various stages of processing, according to some embodiments of the present invention. As shown in fig. 2 to 3, a substrate 203 is provided. In some embodiments, the substrate 203 comprises a substrate 202 and a first insulating layer 204, wherein the first insulating layer 204 is formed on the substrate 202. The first insulating layer 204 may be formed by Atomic Layer Deposition (ALD), physical Vapor Deposition (PVD), chemical Vapor Deposition (CVD), chemical Oxidation (Chemical Oxidation), thermal Oxidation (Heat Oxidation), and/or other suitable methods. In an embodiment, the first insulating layer 204 may include, but is not limited to, an oxide, a nitride, an oxynitride, or a combination thereof, such as silicon oxide, silicon nitride, silicon oxynitride. In some embodiments, the first insulating layer 204 is formed to a thickness of about 0.02 microns to about 0.25 microns, such as about 0.10 microns, about 0.15 microns, or about 0.20 microns.

Continuing with fig. 4, in this step, a metal conductive layer 206 is formed over the first insulating layer 204. In some embodiments, the metal conductive layer 206 can be formed using PVD, CVD, electron Beam Evaporation (Electron Beam Evaporation), sputtering, electroplating, and/or other suitable processes. In an embodiment, the metal conductive layer 206 may include, but is not limited to, titanium (Ti), nickel (Ni), silver (Ag), aluminum (Al), copper aluminum alloy (AlCu), copper aluminum silicon alloy (AlSiCu), or a combination thereof. In one embodiment, the metal conductive layer 206 is formed to a thickness of about 0.3 microns to about 0.5 microns, such as about 0.3 microns, about 0.4 microns, or about 0.5 microns.

Referring now to fig. 5, in this step, a conductive layer 208 is deposited over the metal conductive layer 206. In some embodiments, the conductive layer 208 can be formed by PVD, CVD, electron Beam Evaporation (Electron Beam Evaporation), sputtering, electroplating, and/or other suitable processes. In some embodiments, conductive layer 208 can include, but is not limited to, tantalum (Ta), tantalum nitride (TaN), copper (Cu), titanium (Ti), titanium nitride (TiN), tungsten (W), or a combination thereof. In some embodiments, the thickness of the conductive layer 208 is about 0.05 microns to about 0.6 microns, such as about 0.1 microns, about 0.2 microns, about 0.3 microns, or about 0.4 microns.

Referring now to fig. 6-7, the conductive layer 208 is patterned to form a plurality of working electrodes 212 (only a single working electrode is shown for illustrative purposes). As shown in fig. 6, a patterned photoresist layer (not shown) is formed over the conductive layer 208 by using a mask 210 and a photolithography process, and the photoresist layer may be, for example, a positive photoresist or a negative photoresist. Referring to fig. 7, an etching process is performed on the conductive layer 208 using the patterned photoresist layer to form a plurality of working electrodes 212 and expose the first top surface 205 of the metal conductive layer 206. Each working electrode 212 has a first height H1. Each working electrode 212 has a first top surface 209 and sidewalls 211. Each first top surface 209 is higher than the first top surface 205 of the metal conductive layer 206. Each sidewall 211 is adjacent to each first top surface 209.

With continued reference to fig. 8-9, the metal conductive layer 206 is subjected to a patterning process. As shown in FIG. 8, a patterned photoresist layer (not shown), such as a positive photoresist or a negative photoresist, is formed over the working electrode 212 and the conductive metal layer 206 by using a mask 214 and a photolithography process. Next, referring to fig. 9, an etching process is performed on the metal conductive layer 206 by using the patterned photoresist layer to expose a portion of the upper surface of the underlying first insulating layer 204, such that the metal conductive layer 206 has a sidewall 207 adjacent to the first upper surface 205 and the portion of the upper surface of the underlying exposed first insulating layer 204.

Referring to fig. 10, an insulating material layer 216 is deposited on the first insulating layer 204, the metal conductive layer 206 and the working electrodes 212. In this step, an insulating material layer 216 may, for example, conformally cover the first insulating layer 204, the metal conductive layer 206, and the working electrodes 212. In some embodiments, the insulating material layer 216 may be multiple layers, with the layers being dissimilar from one another. In some embodiments, the layer of insulating material 216 may be multiple layers, with the layers of material being the same as one another. In some embodiments, the layer of insulating material may be formed using PVD, CVD, plasma Enhanced Chemical Vapor Deposition (PECVD), and/or other suitable processes.

In one embodiment, the insulating material layer 216 may include, but is not limited to, an oxide, a nitride, an oxynitride, or a combination thereof, such as silicon oxide, silicon nitride, silicon oxynitride. In one embodiment, the insulating material layer 216 is tetraethoxysilane.

Referring next to fig. 11, a planarization process is performed on the insulating material layer 216 to form a second insulating layer 218. In this step, a planarization process is performed on the insulating material layer 216 to obtain a second insulating layer 218 having a substantially flat upper surface. In one embodiment, the planarization process may be Chemical Mechanical Planarization (CMP) and/or other suitable processes. In some embodiments, the insulating material layer 216 is a plurality of insulating material layers, and the layers of material are different from each other, so that the planarization process is more efficient.

Referring finally to fig. 12, a portion of second insulating layer 218 is removed by an appropriate etching process such that second upper surface 213 of second insulating layer 218 is interposed between first upper surface 205 of metal conductive layer 206 and first top surface 209 of working electrodes 212. The working electrodes 212 protrude from the second top surface 213 of the second insulating layer 218, and the protruding portions have a second height H2, which is a vertical distance from the first top surface 209 to the second top surface 213 of the second insulating layer 218. In some embodiments, the second height H2 is about 0.01 microns to about 0.5 microns, such as about 0.05 microns, 0.15 microns, about 0.3 microns, or about 0.45 microns. In some embodiments, a biological probe may be further modified over the working electrodes 212 such that the biological probe is attached to the first top surface 209 of the working electrodes 212.

The biosensing assembly manufactured according to various embodiments of the present invention is compatible with various biosensing devices. FIG. 13 is a top view of a biosensing device 300 according to some embodiments of the present invention, and FIG. 14A is a cross-sectional view taken along line AA in FIG. 13. As shown in fig. 13 and 14A, the biosensor device 300 includes a substrate 303, a metal conductive layer 306a, a metal conductive layer 306b, a second insulating layer 308, a plurality of working electrodes 310, a counter electrode 312, a biological probe 314, a signal detection unit 316, and a conducting wire 318.

Each of the working electrode 310 and the counter electrode 312 may be electrically connected to the signal detection unit 316 by one or more wires 318. Accordingly, as shown in fig. 14A, when a voltage is applied to the working electrodes 310, the electrodes 310 generate respective electric fields E surrounding the corresponding working electrodes 310. At this time, a sample to be tested is then provided to contact the biological probe 314. If the target molecule in the sample to be detected binds to the bio-probe 314, the working electrodes 310 generate a signal, and the generated signal is transmitted to the signal detection unit 316 through the conducting wire 318, so as to detect the presence of the target molecule.

With reference to fig. 14A, a metal conductive layer 306b is disposed on the first insulating layer 304. The counter electrode 312 is disposed on the metal conductive layer 306 b. The plurality of working electrodes 310 are disposed on the first upper surface 307 of the metal conductive layer 306 a. In some embodiments, the material of metal conductive layer 306b is the same as the material of metal conductive layer 306 a. In some embodiments, the material of metal conductive layer 306b is different from the material of metal conductive layer 306 a. The substrate 303, the base 302, the metal conductive layer 306a, the second insulating layer 308, the working electrodes 310, and the biological probes 314 may be the same as the substrate 103, the base 102, the metal conductive layer 106, the second insulating layer 108, the working electrodes 110, and the biological probes 112, and thus, the description thereof is not repeated.

Referring to fig. 14B, a partial enlarged view is shown in fig. 14A. When a voltage is applied to the working electrodes 310, the working electrodes 310 generate respective electric fields. Illustratively, the E75 field plots the field lines that connect 75% of the maximum field strength at each point in space. In other words, the electric field intensity at each point in the range "covered by the electric field E75" is greater than 75% of the maximum electric field intensity. Illustratively, the E50 field depicts the field lines that connect 50% of the maximum electric field strength at each point in space. In other words, the electric field intensity at each point in the range "covered by the electric field E50 is greater than 50% of the maximum electric field intensity. According to some embodiments, when a voltage is applied to the working electrodes 310, 75% of the maximum electric field strength (i.e., the maximum electric field strength multiplied by 0.75) occurs at a position displaced from the first top surface 311 downward by about 27-40% of the second height H2 (i.e., where the electric field lines connected by the electric field E75 meet the working electrodes 310); in other words, 75% of the maximum electric field strength occurs at about 60-73% of the second height H2 above the second upper surface 313. According to some embodiments, applying a voltage to the working electrodes 310 causes 50% of the maximum electric field strength (i.e., the maximum electric field strength multiplied by 0.5) to occur at a location displaced from the first top surface 311 downward by about 80-93% of the second height H2 (i.e., where the electric field lines connected by the electric field E50 meet the working electrodes 310); in other words, 50% of the maximum electric field strength occurs at about 7-20% of the second height H2 above the second upper surface 313.

Electric field analysis simulation

In the experiment, COMSOL Multiphysics 4.4 simulation analysis software is used for simulating and analyzing the electric field intensity. As shown in the table one below, when the working electrode is circular, example 1 is a circular working electrode with a radius of 0.05 microns and the maximum electric field value is 2.86x 106 (v/m); example 2 is a circular working electrode with a radius of 0.1 micron, with a maximum electric field value of 1.85x 106 (v/m); example 3 is a circular working electrode with a radius of 0.2 microns and a maximum electric field value of 7.75x 105 (v/m).

Watch 1

Working electrode	Radius of electrode (mum)	Maximum electric field value (v/m)
			Example 1	0.05	2.86x 10 6
Example 2	0.1	1.85x 10 6
			Example 3	0.2	7.75x 10 5

From the above, it can be seen that the maximum electric field value increases as the radius of the working electrode decreases. Next, as shown in Table II below, the coverage and strength of the electric field in the salient portion of the working electrode were simulated. When the working electrode is a conventional planar working electrode, the height is 0 microns, so there is no sidewall, no matter 100%, 75% or 50% of the maximum electric field strength is present on the surface of the working electrode. Then, as shown in the second table below, when the second height H2 of the working electrode is 0.15 μm, calculated from the top surface of the working electrode to the lower insulating layer, 75% of the maximum electric field intensity occurs at a distance of 0.05 μm from the top surface of the working electrode; and 50% of the maximum electric field intensity occurs at a distance of 0.13 microns from the top surface of the working electrode.

Watch two

In summary, according to various embodiments of the present invention, the bio-sensing device has a working electrode protruding from the insulating layer. In electrochemical reactions, charged objects move faster when the electric field is larger. The higher the current density results.

An Electrochemical reaction formula (Electrochemical Methods: fundamentals and applications, allen J.Bard, larry R.Faulkner, wiley. ISBN: 0471043729) is known as follows:

J _A (x, t) represents the current density of the charged object A at position x, time t. z is a radical of formula _A Representing the valence of the charged object a. D _A Representing the diffusion coefficient of the charged object a. C _A (x, t) represents the concentration of the charged object A at position x, time t. ε (x) represents the electric field experienced by the charged object A at location x. The protruding working electrode enables the electric field to cover a wider range, and movement of the charged object is influenced by the wider electric field covering range, so that the electrochemical reaction efficiency is improved, and the signal intensity is further increased. Therefore, the working electrode made by the embodiment of the invention has smaller width than the area of the conventional plane electrode, thereby improving the sensitivity.

In the embodiment shown in fig. 14A, the protrusion heights of the working electrode 310 and the counter electrode 312 are the same, i.e., the first top surface 311 of the working electrode 310 and the top surface of the counter electrode 312 are located on the same plane, but not limited thereto. In one embodiment, referring to fig. 15, the second insulating layer 308 covers the metal conductive layers 306a and 306b and the sidewalls 305 thereof, and partially covers the sidewalls 309 of the working electrode 310 and the counter electrode 312, such that the working electrode 310 and the counter electrode 312 protrude from the second upper surface 313 of the second insulating layer 308. Unlike the embodiment shown in fig. 14A, the second top surface 3121 of the counter electrode 312 shown in fig. 15 is higher than the first top surface 311 of the working electrode 310. For example, the difference in height from the first top surface 311 of the working electrode 310 to the second top surface 3121 of the counter electrode 312 is less than 0.15 microns, and in some embodiments, the difference in height from the first top surface 311 of the working electrode 310 to the second top surface 3121 of the counter electrode 312 is less than 0.12 microns, or less than 0.1 microns, or less than 0.05 microns.

For example, the third height H3 of the counter electrode 312 protruding from the metal conductive layer 306b, i.e. the third height H3 from the second top surface 3121 of the counter electrode 312 to the first top surface of the metal conductive layer 306b, is between 0.05 micrometers and 1 micrometer. In some embodiments, the third height H3 of the counter electrode 312 may be 0.1 microns, 0.15 microns, 0.2 microns, 0.25 microns, 0.3 microns, 0.35 microns, 0.4 microns, 0.45 microns, 0.5 microns, 0.55 microns, 0.6 microns, or 0.65 microns. In one embodiment, the counter electrode 312 protrudes beyond the fourth height H4 of the second insulating layer 308, i.e., the fourth height H4 from the second top surface 3121 of the counter electrode 312 to the second top surface 313 of the second insulating layer 308 is between 0.01 micrometers and 0.55 micrometers. In some embodiments, the fourth height H4 of the counter electrode 312 may be 0.1 microns, 0.15 microns, 0.2 microns, 0.25 microns, 0.3 microns, 0.35 microns, 0.4 microns, 0.45 microns, or 0.5 microns.

The second height H2 of the working electrode was set to 0.05 μm, and the electric field strength was simulated and analyzed by COMSOL Multiphysics 4.4 simulation analysis software, and the analysis results are shown in table three. The maximum electric field value is decreased when the fourth height H4 of the counter electrode is less than the second height H2 of the working electrode (comparative example 1) compared to when the fourth height H4 of the counter electrode is equal to the second height H2 of the working electrode (comparative example 2). When the fourth height H4 of the counter electrode is greater than the second height H2 of the working electrode (examples 4 and 5), the maximum electric field value can be enhanced. It should be noted that, when the height difference between the fourth height H4 of the counter electrode and the second height H2 of the working electrode is greater than 0.15 μm (embodiment 6), the maximum electric field value is also decreased, and therefore, the height difference between the fourth height H4 of the counter electrode and the second height H2 of the working electrode should be less than 0.15 μm.

Watch III

It will be appreciated that the distance between the working electrode and the counter electrode will also affect the maximum electric field value of the working electrode. For example, in a plurality of working electrodes arranged in an array, the maximum electric field value of the working electrode far from the counter electrode is relatively small. In order to increase the maximum electric field value of the working electrodes, referring to fig. 16, in an embodiment, the substrate may be divided into a plurality of working electrode areas WEA, and a plurality of working electrodes 310a, 310b or 310c are disposed in each working electrode area WEA. The counter electrodes 312a, 312b include a plurality of finger structures 3122. The finger 3122 of the counter electrode 312a, 312b extends to between the working electrode areas WEA to form a structure in which the counter electrode 312a, 312b surrounds each working electrode area WEA in a U-shape or a ring shape, so that the distances from the working electrodes 310a, 310b or 310c to the counter electrode 312a or 312b in each working electrode area WEA are similar to enhance the maximum electric field value of the working electrodes 310a, 310b or 310c far from the counter electrode 312a or 312b, thereby enhancing the signal strength. In one embodiment, the major-axis to minor-axis ratio of each working electrode region WEA is between 0.8 and 1.2. In a preferred embodiment, the major-to-minor axis ratio of each working electrode region WEA is approximately 1.

Referring to fig. 16 again, in an embodiment, the bio-sensing device of the invention further includes reference electrodes 319a, 319b, 319c, which have a structure similar to the counter electrode, that is, the top surfaces of the reference electrodes 319a, 319b, 319c are higher than the top surfaces of the working electrodes 310a, 310b, 310c, and the functions thereof are well known in the art of the invention and thus are not described herein again. Working electrodes 310a, 310b are mated to counter electrode 312a, and working electrode 310c is mated to counter electrode 312 b. The working electrodes 310a and 310b can be connected to different biological probes to detect different target molecules simultaneously. Alternatively, the working electrodes 310a, 310b may be connected to the same biological probe to enhance the sensing signal. In one embodiment, limited to the area of the substrate, a plurality of working electrode areas WEA can be arranged in an array and electrically connected to each other, and the working electrodes 310c can be connected to the same biological probe to enhance the sensing signal.

In summary, the plurality of working electrodes and the pair of electrodes of the bio-sensing device of the invention respectively protrude the insulating layer, and the protruding height of the counter electrode is greater than the protruding height of the working electrode, so that the maximum electric field value of the working electrode can be enhanced to increase the electrochemical reaction and further improve the sensitivity of sensing.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that the summary is readily utilized as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. It should also be understood by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the present disclosure.

Claims (16)

1. A biosensing device, comprising:

a substrate;

a plurality of metal conducting layers, each of which is configured on the substrate and has a first upper surface;

a plurality of working electrodes disposed on the first top surfaces of the corresponding metal conductive layers, wherein each working electrode includes a first top surface, and each first top surface is higher than the first top surface of the metal conductive layer;

a pair of electrodes disposed on the first top surfaces of the corresponding metal conductive layers and adjacent to the plurality of working electrodes, wherein the pair of electrodes includes a second top surface higher than the first top surface; and

an insulating layer covering the metal conductive layer and surrounding the plurality of working electrodes and the counter electrode, wherein a second upper surface of the insulating layer is interposed between the plurality of first top surfaces of the plurality of working electrodes and the first upper surface of the metal conductive layer such that the plurality of working electrodes and the counter electrode protrude from the second upper surface of the insulating layer.

2. The biosensing device of claim 1, wherein the difference in height from said first top surface of each said working electrode to said second top surface of said counter electrode is less than 0.15 microns.

3. The biosensing device of claim 1, wherein the difference in height from said first top surface of each said working electrode to said second top surface of said counter electrode is less than 0.1 microns.

4. The biosensing device of claim 1, wherein a difference in height from said first top surface of each said working electrode to said second top surface of said counter electrode is less than 0.05 micrometers.

5. The biosensing device of claim 1, wherein each of said working electrodes has an aspect ratio of between 0.125 and 7.5.

6. The biosensing device of claim 1, wherein a first height from said first top surface to said first top surface of each of said working electrodes is between 0.05 microns and 1 micron.

7. The biosensing device of claim 1, wherein a second height from said first top surface to said second top surface of each of said working electrodes is between 0.01 microns and 0.55 microns.

8. The biosensing device of claim 1, wherein a third height from said second top surface to said first top surface of said counter electrode is between 0.05 microns and 1 micron.

9. The biosensing device of claim 1, wherein a fourth height from said second top surface to said second top surface of said counter electrode is between 0.01 microns and 0.55 microns.

10. The biosensing device of claim 1, wherein said substrate comprises a plurality of working electrode regions, a plurality of said working electrodes disposed within each of said working electrode regions, and said counter electrode comprises a plurality of fingers extending between said plurality of working electrode regions.

11. The biosensing device of claim 10, wherein each of said working electrode regions has a ratio of major to minor axes of between 0.8 and 1.2.

12. The biosensing device of claim 10, wherein said counter electrode surrounds each of said working electrode regions in a U-shape or a ring shape.

13. The biosensing device of claim 1, wherein said insulating layer covers a sidewall of said metal conductive layer.

14. The biosensing device of claim 1, wherein said insulating layer partially covers each of said working electrode and a sidewall of said counter electrode.

15. The biosensing device of claim 1, wherein each of said working electrodes is a cylinder or a regular polygonal cylinder.

16. The biosensing device of claim 1, wherein each of the working electrodes comprises at least one biological probe, and the biological probe is a nucleic acid, a cell, an antibody, an enzyme, a polypeptide, a peptide, an aptamer, a carbohydrate, or a combination thereof.

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