A chemical gas sensor chip based on metal atom clusters using dielectrophoresis technology

Abstract

This invention discloses a chemical gas sensor chip based on metal atom clusters, belonging to the field of gas detection technology. The chip, from the inside out, includes a silicon oxide substrate, an oxide layer, metal electrodes, and a metal atom cluster channel. The metal electrodes in this invention are deposited on the oxide layer and include three electrodes: a bias electrode 2, a coupling electrode 3, and a counter electrode 4. The metal atom cluster channel uses nanoscale metal atom clusters as the material, assembled between the coupling electrode 3 and the counter electrode 4 using dielectrophoresis to form an atomic-level metal atom cluster channel. This not only improves the channel's conductivity and gas sensitivity but also facilitates the large-scale manufacturing and integration of the sensor.

Description

Technical Field

[0001] This invention belongs to the field of gas detection technology, specifically relating to a chemical gas sensor chip based on metal atom clusters using dielectrophoresis technology. Background Technology

[0002] Chemical gas sensors play an irreplaceable role in fields such as trace hazardous gas monitoring, early warning of explosive environments, and biological metabolic analysis. Existing sensors mostly rely on metal oxides, conductive polymers, or noble metal nanostructures as sensing materials. In recent years, scientists have integrated various nanocluster materials into sensors, thereby creating highly stable and sensitive sensors.

[0003] However, the main limitations of current technology stem from three dimensions: First, traditional nanomaterials (such as gold and silver nanoparticles with a particle size >3nm) suffer from weakened quantum confinement effects, and their surface electronic state distribution is close to that of bulk metals, resulting in low charge transfer efficiency when adsorbing gas molecules; second, conventional deposition techniques (such as inkjet printing and spin coating) are difficult to construct a uniform and dense active layer in submicron-level electrode gaps, which can easily lead to broken conductive channels or excessively high interfacial contact resistance; third, most nano-atomic cluster materials rely on other conductive materials to form devices, which makes the device manufacturing process complex and introduces additional noise sources and reduces sensing stability.

[0004] However, achieving high-density integration of clusters in micro / nano devices simply and at low cost while maintaining their catalytic activity and structural integrity to ultimately realize highly sensitive chemical gas sensors remains a technological bottleneck. Existing methods are complex and place extremely high demands on conductive channel materials and nano-atomic clusters. Summary of the Invention

[0005] The purpose of this invention is to provide a chemical gas sensor chip based on metal atom clusters using dielectrophoresis technology, so as to improve the detection limit of metal atom cluster-based sensors in the field of chemical gas detection.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A chemical gas sensor chip based on metal atom clusters using dielectrophoresis technology comprises, from the inside out, a silicon oxide substrate, an oxide layer, metal electrodes, and a metal atom cluster channel; the chemical gas sensor structure is fabricated through the following steps:

[0008] The pattern of micro / nano metal electrodes 1 was written on the oxide layer using an electron beam direct writing exposure device. Gaps existed between the nano-metal electrodes 1. Then, development and deposition of a chromium alloy were performed. Next, measurement electrodes (2, 3, 4) were exposed on the surface using ultraviolet lithography. Gaps existed between one of the measurement electrodes (i.e., bias electrode 2 and coupling electrode 3), and chromium alloy was deposited on them through development and vapor deposition. Finally, the device structure was obtained after cleaning with acetone, ethanol, and deionized water, and then drying.

[0009] Furthermore, the silicon substrate is a silicon oxide substrate or an oxide wafer of silicon.

[0010] Furthermore, the thickness of the chromium alloy metal electrode is 55 nm, wherein 5 nm of chromium metal is first deposited at a deposition rate of [missing information]. Gold was deposited at a depth of 50 nm at a deposition rate of [missing information].

[0011] Furthermore, the gap between the nano-metal electrodes 1 is 50 nm, the electrode width is 50 nm, the gap between the measuring electrode on one side (i.e., the bias electrode 2 and the coupling electrode 3) is 2 μm, and the electrode width is 300 μm.

[0012] Furthermore, the metal atom cluster-based chemical gas sensor chip based on dielectric electrophoresis is fabricated through the following steps:

[0013] Metal atom clusters were dispersed in a solution to form a 3.25 mM metal atom cluster solution. The atom cluster solution was then dropped into the area between nanoelectrodes 1 using a pipette to cover nanoelectrodes 1. A high-frequency pulse voltage was applied between bias electrode 2 and counter electrode 4. After half an hour, the surface metal atom clusters were washed away with ethylene glycol and ethanol, respectively, and then dried with nitrogen gas to obtain a chemical gas sensor chip based on metal atom clusters using dielectrophoresis technology.

[0014] Furthermore, the applied pulsed high-frequency voltage has a frequency of 10MHz and an amplitude of 1V.

[0015] Beneficial effects of the present invention:

[0016] The device structure in this invention has two capacitors. The first capacitor exists between the coupling electrode 3 and the counter electrode 4. Because the electrode pair area is small, the capacitance is small and the capacitive reactance is large. The second capacitor exists between the bias electrode 2 and the coupling electrode 3. Its electrode pair area is large, so the capacitance is relatively large and the capacitive reactance is small. When a high-frequency voltage is applied, a strong electric field is formed between the coupling electrode 3 and the counter electrode 4. The strongest electric field is located in the region where the electrode and the oxide layer are in contact. Under the influence of the strong electric field, metal atom clusters are orderly arranged and assembled between the two electrodes, connecting at the bottom to form a conductive channel with only two or three layers. This structure allows for the large-scale assembly of tens of thousands of sensing units on a wafer, which plays an important role in improving the device fabrication rate and reducing costs.

[0017] Metal atom clusters are recognized as highly efficient catalysts, possessing excellent gas adsorption and desorption properties. Gas molecules can rapidly adsorb onto the surface of metal atom clusters and undergo chemical reactions, leading to significant changes in electrical signals that facilitate detection. In the presence of gas, electron transfer occurs on the surface of the metal atom clusters, and the resulting resistance changes can be accurately detected to quantify gas concentration. With the aid of dielectrophoresis, metal atom clusters are orderly assembled in channels without aggregation, forming relatively thin and dispersed nanoscale conductive channels, increasing channel conductivity. This structure significantly increases the specific surface area of ​​the metal atom clusters, exposing more metal atoms and increasing the probability of contact with gas molecules. This structure not only improves gas adsorption efficiency but also promotes gas decomposition and reaction on the surface of the metal atom clusters, further enhancing sensor sensitivity. Specifically, the channel structure provides more reaction sites, allowing more gas molecules to interact with the metal atom clusters, resulting in more significant resistance changes and thus achieving highly sensitive detection. Attached Figure Description

[0018] The invention will now be further described with reference to the accompanying drawings.

[0019] Figure 1 This is a structural diagram of the chemical gas sensor prepared in Example 1 of the present invention.

[0020] Figure 2 This is a response diagram of the platinum metal atom cluster sensor prepared in Example 2 of the present invention to different concentrations of hydrogen gas. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] A gas sensor chip based on metal atom clusters using dielectrophoresis technology comprises, from the inside out, a silicon oxide substrate, an oxide layer, metal electrodes, and metal atom cluster channels. The oxide layer has a thickness of 300 nm.

[0023] Example 1

[0024] This embodiment provides a gas sensor structure, which is prepared through the following steps:

[0025] The silicon oxide substrate was cleaned with acetone, isopropanol, and deionized water. Then, a 250nm PMMA electron beam resist was spin-coated onto the silicon wafer surface. Nanoscale metal electrode patterns were then written on the resist using electron beam exposure. After development, a 5nm chromium metal layer was deposited on the surface at a deposition rate of [missing information]. Gold was deposited at a depth of 50 nm at a deposition rate of [missing information]. After stripping, measurement electrodes are exposed on the surface using ultraviolet lithography, with a gap between one side of the measurement electrodes. A chromium alloy of the same thickness is then deposited through development and vapor deposition. Finally, the device structure is obtained by cleaning with acetone, ethanol, and deionized water, followed by drying. (See device structure reference). Figure 1 As shown.

[0026] Example 2

[0027] This embodiment provides a hydrogen sensor chip based on platinum metal atom clusters using dielectrophoresis technology, which is fabricated through the following steps:

[0028] Platinum metal clusters were dispersed in solution to form a 3.25 mM metal cluster solution. This solution was then dropped into the region between nanoelectrodes using a pipette to cover the nanoelectrodes. A high-frequency pulsed voltage (10 MHz frequency, 1 V amplitude) was applied between the bias and counter electrodes. After half an hour, the platinum metal clusters on the surface were washed away with ethylene glycol and ethanol, respectively, and then dried with nitrogen gas to obtain a hydrogen sensor chip based on platinum metal clusters using dielectrophoresis.

[0029] Performance testing was conducted on Example 2:

[0030] The prepared sample is bonded to a chip carrier using aluminum wire bonding, and the chip carrier is then placed in a custom-made test base containing a sealed cavity. The test base has two vents at the top, used for introducing the test gas or background gas and for venting gas, respectively. The test base is connected to a high-precision measuring instrument to monitor and capture changes in the electrical signal.

[0031] The tests were conducted at room temperature. Different concentrations (20-1000 ppb) of the test gas (hydrogen) were introduced, and the electrical signals were recorded. Each time, hydrogen was introduced for 30 seconds, followed by nitrogen for analysis and recovery, also for 30 seconds. Different concentrations were sequentially introduced from low to high. Test results are available in the reference section. Figure 2 As shown.

[0032] The recorded results show that the hydrogen sensor prepared in this invention maintains high detection performance even at extremely low hydrogen concentrations. The pink area in the figure represents the time periods when different concentrations of hydrogen were introduced.

[0033] The time taken from the start of the response to reaching 10% of the response current value was recorded and denoted as the response time; the results are shown in Table 1 below:

[0034] Table 1

[0035]

[0036]

[0037] The test results show that the hydrogen sensor structure prepared by this invention has good sensitivity, low operating temperature requirements, and fast response time to different concentrations of hydrogen.

[0038] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A chemical gas sensor chip based on metal atom clusters using dielectrophoresis technology, comprising, from the inside out, a silicon oxide substrate, an oxide layer, metal electrodes, and metal atom cluster channels; characterized in that, The gas sensor chip is manufactured from an oxide wafer. The device structure of the gas sensor chip is prepared through the following steps: a micro / nano metal electrode pair pattern is written on the oxide layer using an electron beam direct writing exposure device, with gaps between the micro / nano metal electrode pairs. Then, a chromium alloy is deposited after development. Next, a measurement electrode is exposed on the surface using ultraviolet lithography. One side of the measurement electrode is a bias electrode and a coupling electrode, with gaps between them. The other side of the measurement electrode is a reverse electrode, and the coupling electrode is connected to one micro / nano metal electrode, while the reverse electrode is connected to another micro / nano metal electrode. Then, a chromium alloy is deposited by development and vapor deposition. Finally, the device structure is obtained by cleaning with acetone, ethanol, and deionized water and drying. The chemical gas sensor chip based on metal atom clusters using dielectric electrophoresis technology is fabricated through the following steps: Metal atom clusters were dispersed in a solution to form a 3.25 mM metal atom cluster solution. The metal atom cluster solution was then dropped into the region between micro / nano metal electrode pairs using a pipette, covering the micro / nano metal electrode pairs. A high-frequency pulse voltage was applied between the bias electrode and the counter electrode. After half an hour, the surface metal atom clusters were washed away with ethylene glycol and ethanol, respectively, and then dried with nitrogen gas to obtain a chemical gas sensor chip based on metal atom clusters using dielectrophoresis technology. The gap between the micro / nano metal electrode pairs was 50 nm, the electrode width was 50 nm, and the gap between the bias electrode and the coupling electrode was 2 μm.

2. A chemical gas sensor chip based on metal atom clusters using dielectrophoresis technology according to claim 1, characterized in that, The metal atom clusters mentioned include gold, silver, platinum, or palladium.

3. A chemical gas sensor chip based on metal atom clusters using dielectrophoresis technology according to claim 1, characterized in that, The high-frequency pulse voltage has a frequency of 10 MHz and an amplitude of 1 V.

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