Nanofabrication of deterministic diagnostic devices

Abstract

A diagnostic chip for detecting biomarkers and trace nanoparticles in chemical mixtures or water. The diagnostic chip includes one or more inputs into at least one of which a sample containing particles of different sizes is introduced. In addition, the diagnostic chip includes a plurality of separation zones through which the sample is passed under pressure. Each separation zone includes a deterministic lateral displacement array, the deterministic lateral displacement arrays of two or more of the separation zones having different etch depth profiles. In this way, the diagnostic chip can effectively detect biomarkers and trace nanoparticles in chemical mixtures or water.

Description

[0001] Cross-referencing This disclosure claims priority to U.S. Provisional Patent Application No. 63 / 058,284, filed July 29, 2020, entitled "Nanofabrication of Point-of-Use Deterministic Diagnostic Devices," the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates generally to diagnostic devices, and more specifically to the nanofabrication of a deterministic diagnostic device. Background Technology

[0003] For example, diagnostic equipment, such as medical diagnostic devices, helps clinicians measure and observe various aspects of a patient's health so they can form a diagnosis. Once a diagnosis is made, clinicians are able to develop an appropriate treatment plan.

[0004] Medical diagnostic equipment is available in outpatient nursing centers, emergency rooms, inpatient wards, and intensive care units for both adults and pediatrics.

[0005] This diagnostic device can be used to detect small concentrations of biomolecules to provide early disease detection and monitor patient response to treatment. This diagnostic tool can help clinicians make crucial decisions regarding treatment methods and improve patient outcomes. In the early stages of disease, disease biomarkers are present at very low concentrations and are difficult to detect in typical media such as blood, urine, plasma, and serum. Capturing and isolating biomarkers, such as tumor cells and exosomes, allows sensors to detect them. In a biomedical context, biomarkers or biolabels are measurable indicators of a biological state. Similarly, detecting trace amounts of nanoparticles in chemical mixtures or water also has important applications.

[0006] Unfortunately, there are currently no means for diagnostic devices to effectively detect these biomarkers or to effectively detect trace amounts of nanoparticles in chemical mixtures or water. Summary of the Invention

[0007] In one embodiment of the invention, a diagnostic chip includes one or more inputs, into which a sample containing particles of different sizes is introduced to at least one of the one or more inputs. The diagnostic chip also includes a plurality of separation zones, wherein the sample is pressurized as it passes through the plurality of separation zones, each of the plurality of separation zones including a deterministic lateral displacement array, two or more of the deterministic lateral displacement arrays having different etch depth profiles.

[0008] In another embodiment of the invention, a device for separating one or more biological species includes a separation region comprising a micrometer- or nanometer-scale structure, wherein the underlying substrate of the separation region is non-porous. The device also includes at least one output region, wherein the underlying substrate of the at least one output region is porous.

[0009] To better understand the detailed description of the invention below, the foregoing has summarized the features and technical advantages of one or more embodiments of the invention. Other features and advantages of the invention will be described below, which may form the body of the claims. Attached Figure Description

[0010] The invention can be better understood when the following detailed description is considered in conjunction with the accompanying drawings, wherein: Figure 1 A silicon nanopillar fabricated using catalyst-influenced chemical etching (CICE) according to an embodiment of the invention is shown, which is used for particle separation based on deterministic lateral displacement (DLD). Figure 2 The invention illustrates an apparatus ("desktop" device) for supplying liquid and gas to a diagnostic chip ("disposable chip") and for examining the diagnostic chip, according to an embodiment of the invention. Figures 3A to 3D An embodiment of a disposable diagnostic chip according to an embodiment of the present invention is shown; Figures 4A to 4B A second embodiment of a disposable diagnostic chip according to an embodiment of the present invention is shown; Figure 5A A top view of a column array according to an embodiment of the present invention is shown; Figure 5B Three arrangements of the column array according to an embodiment of the present invention are shown; Figure 6 An embodiment of a diagnostic chip according to an embodiment of the present invention is shown, wherein micro / nanofiber silicon is integrated with a top transparent substrate, and an array of micro / nanofiber pillars forms a microscale gap between the bottom of the pillars and the top substrate as spacers. Figure 7 A flowchart illustrating a method for manufacturing silicon nanopillars according to an embodiment of the present invention is shown; Figures 8A to 8D The use according to an embodiment of the present invention is described. Figure 7 A cross-sectional view of the silicon nanopillars fabricated using the steps described herein; Figures 9A to 9D Each of the embodiments of the present invention is shown in Figures 8A to 8D Images of a 4-inch wafer after each process step are shown; Figure 10 A top-down scanning electron microscope (SEM) image of silicon nanowires fabricated using metal-assisted chemical etching (MACE) according to an embodiment of the present invention is shown. Figure 11 A cross-sectional SEM image of silicon nanowires fabricated using MACE according to an embodiment of the present invention is shown; Figure 12 An exemplary side barrier array for particle separation according to an embodiment of the present invention is shown; Figure 13 A flowchart illustrating a method for manufacturing a self-aligned post using the MACE process according to an embodiment of the present invention is shown; and Figures 14A to 14C The use according to an embodiment of the present invention is described. Figure 13 The steps described above utilize the MACE process to create a cross-sectional view of the self-aligned column. Detailed Implementation

[0011] As described in the background section, there are currently no means for diagnostic devices to effectively detect biomarkers or to effectively detect trace amounts of nanoparticles in chemical mixtures or water.

[0012] The principle of this invention is to provide a method for effectively detecting biomarkers and effectively detecting trace nanoparticles in chemical mixtures or water.

[0013] In one embodiment, the principle of the invention is to perform this detection using a technique referred to herein as "deterministic lateral displacement (DLD)." DLD is a microfluidic technique that uses a specific arrangement of column arrays placed within microfluidic channels to separate particles in a fluid medium according to their size. The gaps between the columns and the placement of the columns determine the separation mechanism. Further descriptions of DLD can be found in Huang et al., "Continuous Particle Separation through Deterministic Lateral Shift," Science, Vol. 304, No. 5673, May 2004, pp. 987-990; McGrath et al., "Deterministic Lateral Displacement for Particle Separation: A Review," Lab on a Chip, Vol. 14, No. 21, 2014, pp. 4139-4158; Inglis et al., "Critical Particle Size for Fractionation by Deterministic Lateral Displacement," Lab on a Chip, Vol. 6, No. 5, May 2006, pp. 655-658; and Wunsch et al., "Nanoscale Lateral Displacement Arrays for the Separation of Exosomes and Colloids Down to 20nm," Nature Nanotechnology, Vol. 11. No. 11, November 2016, pp. 936-940, the entire contents of which are incorporated herein by reference.

[0014] Please refer to the attached diagram for details. Figure 1 A silicon nanopillar fabricated using catalyst-influenced chemical etching (CICE) according to an embodiment of the invention is shown, which is used for DLD-based particle separation.

[0015] like Figure 1As shown, the column array 101 required for DLD receives a sample containing a mixture of particles of various sizes and shapes through inlet 102, and generates multiple streams with particles separated by size and / or shape through output stream 103. In one embodiment, the DLD column array 101 generates a pattern that maximizes separation efficiency and yield using variables such as column size and spacing, column shape (e.g., circular, triangular, rhomboid, streamlined, etc.), column array position and tilt angle, and column height before collapse. Furthermore, as... Figure 1 As shown, illustration 104 of the sample in inlet 102 corresponds to a 2-micrometer-high column with a spacing of 30 nanometers, fabricated using CICE with ruthenium as a catalyst. Furthermore, as... Figure 1 As shown, Figure 105 of the output stream 103 includes silicon (Si) pillars fabricated using CICE with a height of 4 micrometers and a spacing of 30 nanometers, wherein the CICE uses gold as a catalyst. Furthermore, as... Figure 1 As shown, Figure 106 of the DLD pillar array 101 includes silicon (Si) nanopillars with a rhomboid cross-section.

[0016] In one embodiment, the DLD column array 101 is fabricated using nanolithography techniques, such as nanoimprint lithography combined with metal-assisted chemical etching (MACE) processes. Further details regarding DLD and its fabrication using MACE can be found in Cherala et al., "Nanoshape Imprint Lithography for Fabrication of Nanowire Ultracapacitors," IEEE Transactions on Nanotechnology, Vol. 15, No. 1, January 2016, pp. 448-456; Mallavarapu et al., "Enabling Ultra-High Aspect Ratio Silicon Nanowires Using Precise Experiments for Detecting Onset of Collapse," Nano Letters, Vol. 20, No. 11, 2020, pp. 7896-7905; and Mallavarapu et al., "Scalable Fabrication and Metrology of Silicon Nanowire Arrays made by Metal Assisted Chemical Etching," IEEE Transactions on Nanotechnology, Vol. 20, 2021, pp. 83-91, the entire contents of which are incorporated herein by reference.

[0017] Now for reference Figure 2 , Figure 2 The invention illustrates an apparatus (“desktop” device) for supplying liquid and gas to a diagnostic chip (“disposable chip”) and for examining the diagnostic chip, according to an embodiment of the invention.

[0018] like Figure 2 As shown. Desktop devices 201A to 201D provide multiple inputs (labeled I1, I2, I3, I4, I5, I6, I7, I8, I9, I10, I11, I20 ... S Equipment 201A to 201D can be collectively referred to as equipment 201 or referred to individually. Although Figure 2 Four devices 201 are shown, but it should be noted that the principles of the present invention can be applied to any number of desktop devices 201.

[0019] Refer again Figure 2 If the chip 202 is positioned with sufficient precision on the chip holder 203, which is connected to the device body via a frame, the chip 202 registers with each inlet and is able to receive buffer solutions (e.g., purified water), pressure sources, solvents required for the operation of the chip 202, etc. The chip 202 also receives "samples," which can be a patient's blood, urine, saliva, serum, etc. In one embodiment, the system is designed to prevent "samples" from flowing back into any reservoirs in the device that hold cleaning fluids. The disposable diagnostic chip 202 will be described further below.

[0020] In addition, such as Figure 2 As shown, “SZ” corresponds to sensor area 204, which is optically inspected using instrument 205 marked “M / S”. This instrument can be a microscope, fluorescence microscope, spectrometer, Raman spectrometer, etc.

[0021] Now for reference Figures 3A to 3D , Figures 3A to 3D An embodiment of a disposable diagnostic chip according to one embodiment of the present invention is shown.

[0022] Figure 3A A top view of the diagnostic chip is shown. Figure 3B It shows along Figure 3A The image shows a cross-sectional view in the vertical Y-direction. Multiple inputs (labeled I1, I2, I3, I...) S ) is also shown and represents the same as Figure 2The same inputs are shown. Although only four inputs are shown, these devices can include any number of inputs, such as 25 or more. In one embodiment, a “sample” containing particles of different sizes is introduced into one of inputs I1, I2, or I3. The sample, along with other liquids, such as buffer solutions, is pressurized and passed through regions 1 to 4 (301A to 301D, respectively) (labeled “R1”, “R2”, “R3”, and “R4”, respectively). Regions 301A to 301D can be collectively referred to or individually as region (or “separation zone”) 301. Again, it should be noted that although only four regions are shown, any number of regions may exist, including 25 or more. In one embodiment, these regions are designed to perform tiered filtration of particles such that the size of particles captured in each output reservoir (O1 to O3 and output MZ) (labeled outputs 302A to 302D, respectively) decreases monotonically. Output O4302E collects the remaining liquid and other very small residues (e.g., less than 10 nm or less than 25 nm). Outputs 302A through 302E can be collectively referred to or individually as output 302. The sample flowing through region R1 to output O1 is labeled RO1. Similarly, the sample flowing through region R2 to output O2 is labeled RO2. The size range of the particles that finally stop at O1 after passing through O3, output MZ, and O4 depends on the DLD region R. iThe design of the columns, including their size, spacing, height, arrangement, orientation relative to the flow direction, and cross-sectional shape, determines the range of particles that can be filtered, as illustrated in Huang et al.'s "Continuous Particle Separation Through Deterministic Lateral Displacement," Science, Vol. 304, No. 5673, May 2004, pp. 987-990; McGrath et al.'s "Deterministic Lateral Displacement for Particle Separation: A Review," Labon a Chip, Vol. 14, No. 21, 2014, pp. 4139-4158; and Inglis et al.'s "Critical Particle Size for Fractionation by Deterministic Lateral Displacement," Labon a Chip, Vol. 6, No. 5, May 2006, pp. "Nanoscale Lateral DisplacementArrays for the Separation of Exosomes and Colloids Down to 20 nm," As discussed in Nature Nanotechnology, Vol. 11, No. 11, November 2016, pp. 936-940.

[0023] In one embodiment, it is assumed that region 1 has a large DLD pillar array with a relatively large diameter (e.g., 25 to 50 micrometers), region 2 has a slightly smaller DLD pillar array (e.g., in the range of 5 to 25 micrometers), and region 3 has an even smaller DLD pillar array (e.g., in the range of 0.5 to 5 micrometers). Furthermore, in this design, it is assumed that region 4 has the smallest DLD pillar array (e.g., in the range of 25 nanometers to 500 nanometers). In one embodiment, the spacing between these pillars can be large, making them “sparse” (as discussed further below). Figure 5B(As shown in the figure). In one embodiment, the diameter-to-spacing ratio of "sparse" pillars is 1% to 35% (d / p = 0.01 to 0.35). In one embodiment, the diameter-to-spacing ratio of "medium" pillars is 35% to 65% (d / p = 0.35 to 0.65). In one embodiment, the diameter-to-spacing ratio of "dense" pillars is 55% to 99% (d / p = 0.65 to 0.99). In one embodiment, a combination of nanoimprinting and MACE is used to fabricate these dense pillars, particularly when the spacing between pillars is much smaller than 25 nanometers. Discussions of this fabrication are provided in Mallavarapu et al.'s "Enabling Ultra-High Aspect Ratio Silicon Nanowires Using Precise Experiments for Detecting Onset of Collapse," Nano Letters, Vol. 20, No. 11, 2020, pp. 7896-7905, and Mallavarapu et al.'s "Calable Fabrication and Metrology of Silicon Nanowire Arrays made by Metal Assisted Chemical Etchin G," IEEE Transactions on Nanotechnology, Vol. 20, 2021, pp. 83-91.

[0024] In one embodiment, input I S It is an optional input for a solvent or chemical, which is associated with one of the outputs (in...). Figures 3A to 3B The output MZ corresponds to the mixing region. In one embodiment, the output reaching MZ can be an exosome or antibody with a size in the range of 25 nm to 150 nm. If particles, such as exosomes, are exposed to I... S Upon arrival at MZ, a suitable chemical or solvent can break down the exosome wall and release the exosome's contents, which are biomolecules (biomarkers) representing the cell from which the exosome originated. Finally, in one embodiment, an optional sensor region 204 is present (in... Figure 2 and Figures 3A to 3B (marked as SZ). Therefore, the mixing region (MZ) may include output terminal 302 (e.g., marked as O). FOne of SZ 204 and / or SZ 204. In one embodiment, sensor region 204 captures biomarkers released from exosomes and detects them using instruments such as microscopes, fluorescence microscopes, spectrometers, Raman spectrometers, etc. In particular, if SZ 204 is designed to enhance the Raman signal, it may contain a surface-enhanced Raman spectroscopy (SERS) pattern fabricated in a plasma material, such as Au, Ag, or Cu, or in a more complex material stack, as discussed, for example, in Sharma et al., "SERS: Materials, Applications and the Future," Materials Today, Vol. 15, Nos. 1-2, January-February 2012, pp. 16-25, the entire contents of which are incorporated herein by reference.

[0025] It should be noted that there is evidence that exosomes can be used to deliver transfer growth factors, microRNAs (miRNAs), mRNAs, and enzymes, which play important roles in regulating cellular activity. In immunomodulation, exosome secretion serves as a one-way delivery carrier for miRNAs capable of regulating gene expression in target cells. Cell-free therapies based on exosomes have been identified as a potential approach in regenerative medicine without the need for stem cell implantation. Once cellular exosomes are isolated using the device described herein, these vesicles can be analyzed in two ways. First, proteomic analysis can be performed to identify surface markers such as four-permeable membrane proteins (CD9, CD63, CD81), adhesion proteins, or cell-specific surface markers (T-cell receptors, CAR-T receptors, major histocompatibility complex (MHC) proteins, etc.). These surface markers allow for preliminary identification of exosomes in solution and can provide information on the origin of the vesicles, as well as the potential for recognition between source and target in the physiological environment and the potential for cell-cell communication. The therapeutic potential of exosomes can be further evaluated by analyzing the contents of the exosomes. In one embodiment, the therapeutic potential of exosomes is assessed by cleaving and separating them using an organic solvent such as methanol, and then depositing the contents onto a SERS substrate for protein identification and analysis, or by isolating the contents for further genetic characterization analysis.

[0026] In one embodiment, it may be necessary to etch the different regions to different heights to maintain a reasonable aspect ratio for the pillars. For example, if the pillars fabricated in region 4 (R4) have a diameter of 100 nanometers and the pillars fabricated in region 1 (R1) have a diameter of 25 micrometers, then the etching depth of region 1 may be 25 micrometers, while the etching depth of region 4 may be only 1 micrometer. Figure 3B This variable etching depth in each region illustrates that the transition from one region to the next includes a step. This variation in step height can cause fluid flow problems. For example, at the step between R1 and R2, the step may cause some smaller particles that need to continue to regions 2, 3, or 4 to get stuck at the foot of the step between R1 and R2. This problem can be addressed by... Figures 4A to 4B The alternative embodiments shown solve the problem. Figures 4A to 4B A second embodiment of a disposable diagnostic chip according to an embodiment of the present invention is shown.

[0027] Figure 4A A top view of the diagnostic chip is shown. Figure 4B It shows along Figure 4A The cross-sectional view shown is in the vertical Y-direction. (See diagram below.) Figures 4A to 4B As shown, the transition (between R1 and R2, denoted as R) 12 The interval between R2 and R3 is represented by R. 23 The interval between R3 and R4 is represented as R 34 The surface is designed to be gradient, with ramps between any two regions. Manufacturing these ramps is challenging, and the methods to overcome these manufacturing challenges will be discussed later.

[0028] In multi-region cascaded DLD devices that simultaneously contain micro- and nano-scale DLD regions, a significant challenge is the need to approximately match the flow resistivity as the flow bifurcates and moves toward the respective outputs. For example, various flow resistivities (in Newton-second-meter)... -5 or Ns / m 5 It is desirable for the resistivity of the channel to be within 10 times of each other (in units). The flow resistivity of the channel is defined by the lateral (width) parameter, the channel depth, and the channel length. When the resistivity is too low, it can be increased to better match the resistivity of other paths. This increase can be achieved by using one or more of the following methods: (i) significantly increasing the length—this can be done by using a spiral channel (see e.g., see Figure 3A (i) to effectively achieve O3 output channels) or serpentine channels without any sharp bends that could cause flow interruption; (ii) to increase "dense" column regions with d / p greater than 0.9 or greater than 0.95; and (iii) to reduce the etch height of localized areas of the channel. The last concept is in Figure 3C and Figure 3DAs shown in the figure, both of these figures are Figure 3A The ZZ cross-section. In Figure 3C In this process, the etching depth is constant, which is relatively easy to manufacture. However, in... Figure 3D The etching depth varies in a complex manner, as shown in the diagram. If this variation in etching depth can be created, then cascaded fluid systems can be designed with appropriately matched flow resistance. The variation in etching depth during manufacturing will be discussed further below.

[0029] refer to Figure 5A , Figure 5A A column array 101 according to an embodiment of the present invention is shown. Figure 1 A top view of (e.g.) Figure 5A As shown, the diameter of the column decreases from region R1 to region R4, for example... Figure 3B and Figure 4B As shown in the image. Furthermore... Figure 5B Three arrangements of the column array according to an embodiment of the present invention are shown. For example... Figure 5B As shown, there are three types of column array arrangements: dense 501A, medium 501B, and sparse 501C.

[0030] Figure 6 An embodiment of a diagnostic chip according to one embodiment of the present invention is shown, wherein micro / nanofabricated silicon is integrated with a top transparent substrate 601 (e.g., glass, polydimethylsiloxane, PDMS), and a micro / nanofabrication array (not shown) forms a microscale gap 602 between the bottom of the pillars 603 (e.g., silicon pillars) and the top substrate 601 as spacers. Additionally, an plexiglass substrate 604 is shown, on which optional inlet holes 605 and outlet holes 606 are machined. In one embodiment, as... Figure 6 As shown, the interlayer of plexiglass-silicon-top substrate (604-603-601) is fixed together with screws.

[0031] Now for reference Figure 7 , Figure 7 This is a flowchart of a method 700 for manufacturing silicon nanopillars according to an embodiment of the present invention. Figures 8A to 8D The use according to an embodiment of the present invention is described. Figure 7 A cross-sectional view of the silicon nanopillars fabricated using the steps described herein; refer to Figure 7 , combined Figures 8A to 8D In step 701, thermal oxide 802 is deposited on substrate 801, such as a silicon wafer (e.g., a P-type silicon wafer (100) with a resistivity of 1-10 ohm-cm), as... Figure 8AAs shown. In one embodiment, a thermal oxide 802 with a thickness of 30 to 100 nanometers is grown on a substrate 801.

[0032] In step 702, a thin layer of resist material 803 (e.g., a polymer) is deposited on the oxide 802 and then patterned to form resist pillars 804 (circular), such as pillars of a deterministic lateral displacement pillar array, as... Figure 8A As shown. In one embodiment, the thickness of the resist material is between 10 and 30 nanometers. In another embodiment, the resist material is patterned using imprint lithography.

[0033] In step 703, as Figure 8B As shown, a thin layer of resist 803 and an underlying oxide 802 are etched. In one embodiment, a 10 to 30 nanometer thin layer of resist 803 is removed by oxygen plasma etching (pretreatment). In another embodiment, the oxide layer 802 is etched isotropically using a short-time buffered oxide etch (BOE) (e.g., 6:1) or by using reactive ion etching of the oxide 802 followed by a short-time immersion in BOE.

[0034] In step 704, an optional adhesion layer is deposited ( Figures 8A to 8D (not shown in the image), and then thin film deposition of catalyst 805 is performed, such as... Figure 8C As shown in the figure. In one embodiment, an adhesion layer, such as titanium (Ti), is deposited on the resist pillar 804 and the remaining oxide 802, followed by thin-film deposition of a catalyst 805, such as silver, gold, palladium, platinum, and ruthenium. In one embodiment, the thickness of the adhesion layer is 2 nanometers. In one embodiment, the catalyst type is a MACE catalyst. In one embodiment, the thickness of the catalyst layer 805 is between 2 nanometers and 50 nanometers. In one embodiment, the material of the catalyst 805 is gold with a thickness of 10 nanometers or 4 nanometers.

[0035] In step 705, as Figure 8D As shown, Figure 8C The patterned wafer is immersed in a MACE solution. In one embodiment, the patterned wafer is immersed in a MAC solution containing 12.5 moles of hydrofluoric acid (HF) and 1 mole of hydrogen peroxide (H2O2). In one embodiment, etching can be performed by quenching the wafer, followed by rinsing with water and drying with an air gun supplied with clean dry air (CDA). In one embodiment, Transene can be used. TM Potassium iodide-based etchant selectively removes catalyst 805 (e.g., gold catalyst). Residual resist can be selectively removed using short-duration oxygen plasma.

[0036] In one embodiment, using method 700, the corrosion-resistant column 804 is designed to prevent particle blockage in the sample fluid.

[0037] Figures 9A to 9D Each of the embodiments of the present invention is shown in Figures 8A to 8D Images of a 4-inch wafer after each process step are shown.

[0038] Figure 10 An embodiment of the invention is shown, as described above regarding Figure 7 as well as Figures 8A to 8D The images discussed are top-down scanning electron microscope (SEM) images of silicon nanowires fabricated using MACE. Figure 10 In this context, the scale bar is 1 micrometer.

[0039] Figure 11 An embodiment of the invention is shown, as described above regarding Figure 7 as well as Figures 8A to 8D The discussed section contains cross-sectional SEM images of silicon nanowires fabricated using MACE. Figure 11 In this context, the scale bar is 1 micrometer.

[0040] refer to Figure 7 , Figures 8A to 8D , Figures 9A to 9D , Figure 10 and Figure 11 The aforementioned process offers nanoscale resolution and can be used to fabricate pillars with diameters of 50 nanometers or smaller and spacing of less than 5 nanometers. This process can also simultaneously fabricate small (below 100 nanometers) and large (greater than 25 micrometers) pillars, as well as large etched areas (e.g., square or circular areas with dimensions or diameters ranging from at least 25 micrometers to up to millimeters), on a device region. In one embodiment, such large etched areas are fabricated using a gold catalyst deposited as a thin film (less than 15 nanometers) with or without Ti and featuring an optional annealing step. This results in a gold film with very fine pores, allowing etchant to penetrate the microporous gold to etch large areas. A discussion of porous gold is provided in Nichkalo et al., "Silicon Nanostructures Produced by Modified MacEtchMethod for Antireflective Si Surface," Nanoscale Research Letters, Vol. 12, No. 106, 2017, pp. 1-6, the entire contents of which are incorporated herein by reference.

[0041] In one embodiment, the porous gold film results in the formation of silicon "nanowhiskers" in regions corresponding to the pore locations on the gold film. These silicon nanowhiskers can be selectively removed using techniques such as silicon etching with potassium hydroxide (KOH), or oxidation and etching of the nanowhiskers using hydrofluoric acid (HF), wherein oxidation is performed using oxygen plasma, oxidants such as nitric acid, electrochemical anodizing, etc.

[0042] In one embodiment, to nanoimprint these features, a template copy is fabricated using an electron beam master with holes in the master, and pillars are generated in fused silica after imprinting and reactive ion etching. The fused silica master is then coated with an atomically layered oxide to generate pillars of increased size at a given spacing, as discussed in Cherala et al., "Nanoshape Imprint Lithography for Fabrication of Nanowire Ultracapacitors," IEEE Transactions on Nanotechnology, Vol. 15, No. 1, January 2016, pp. 448-456. The resulting fused silica copy can be used in the aforementioned MACE process following nanoimprinting, such as... Figure 7 and Figures 8A to 8D As shown.

[0043] In one embodiment, Figure 3C and Figure 4B The controllable etching depth variation shown is achieved by using one or more of the following methods.

[0044] In one method, localized temperature is used to control the etch rate of silicon during the MACE process, as discussed in International Application No. PCT / US2018 / 060176, the entire contents of which are incorporated herein by reference. This allows for increased etch rates in regions of the silicon wafer with higher temperatures and enables a gradient etch rate in transition regions from hotter to cooler areas.

[0045] In another approach, the etching rate of a local area is controlled by controlling the amount of etchant supplied to each part of the wafer. This idea of ​​generating variations in etching depth by controlling etchant delivery is illustrated in Figure 3 of Mallavarapu et al.'s "Enabling Ultra-High Aspect Ratio Silicon Nanowires Using Precise Experiments for Detecting Onset of Collapse," Nano Letters, Vol. 20, No. 11, 2020, pp. 7896-7905. One method to create such etchant flow control is: (i) first using... Figure 7 and Figures 8A to 8D The process involves (ii) using the MACE process to generate short-distance uniform etching (e.g., an etching depth of 100 nm) of silicon nanowires; then (ii) removing the wafer from the etchant, quenching it with water, and drying it; then (iii) depositing an inkjet-based ultraviolet (UV)-curable monomer material (e.g., acrylates discussed in Choi et al., "Handbook of Nanofabrication", edited by Gary Wiederrecht, Elsevier Press, October 2009, 310 pages, see pp. 149-181, the entire contents of which are incorporated herein by reference) to selectively block portions of the silicon wafer, followed by (iv) reinserting the wafer into the MACE etchant to continue the MACE process in the unblocked areas. The UV-curable material can be inkjet-sprayed onto any of the following locations: (1) Areas that are completely blocked, where further etching will cease (e.g., areas R4, MZ, and SZ, once their sufficient etching depth is reached), or (2) Partially blocked areas (where the individual inkjet droplets are distributed and UV-cured before they fully fuse, thus leaving small gaps in the gap regions between the droplets, which define the amount of etchant that penetrates into the underlying silicon for MACE etching), or (3) An area without obstruction, in which there are no inkjet monomers, so that MACE etching can continue unimpeded.

[0046] In another embodiment, the DLD column array 101 (see...) Figure 1 It can act as a barrier for fluid flow and lateral leakage (see discussion below). Figure 12 A dense array of pillars (interlaced or otherwise). These barrier arrays are essentially like... Figure 5B The term "dense pillars" is used here, and can be "super-dense." "Super-dense" refers to a d / p ratio greater than 0.9 or greater than 0.95. The cross-sections of the individual pillars in the barrier array are not necessarily circular and symmetrical. For example, they can also be asymmetrical. Asymmetrical shapes will restrict fluid leakage from the DLD pillar array 101 to the outside, but allow fluid to be injected into the DLD pillar array 101 from the outside, such as... Figure 12 As shown, this can be used to perform in-situ operations on the contents of a DLD. Figure 12 An exemplary side barrier array for particle separation is shown according to an embodiment of the present invention.

[0047] refer to Figure 12 , Figure 12 The diagram illustrates a DLD column array 101, an inlet 102, and an outlet flow 103. In one embodiment, the barrier layer / array 1201 can be fabricated together with the DLD column array 101 discussed above without any separate fabrication steps. The width of the side barrier array can range from less than one micrometer to more than one millimeter. The advantage of these barrier arrays is that, over a time span in these devices, the barriers prevent any relevant particles from passing through, allowing only a very small percentage of liquid to permeate.

[0048] In one embodiment, the principle of the invention is to generate a porous layer for draining liquid prior to surface-enhanced Raman spectroscopy (SERS) detection.

[0049] In one embodiment, when detecting a buffer solution containing biological or chemical particles using the detection device discussed herein, if SERS detection is used, drainage can be achieved using a porous silicon layer beneath the gold pattern to enhance SERS detection. In one embodiment, the porous silicon layer is designed as a drain for the sample liquid while preventing particles in the fluid from penetrating into the pores of the porous silicon layer. In one embodiment, the porous silicon layer is used in MACE... Figure 2 , Figures 3A to 3B and Figures 4A to 4BThe SERS “bathtub” is formed after the SZ region in the DLD array is generated. In one embodiment, the SERS “bathtub” has an area of ​​2 mm × 2 mm and a depth of 1 μm and is connected to the desired DLD array outlet. The “bathtub” is etched together with the remaining portions of the DLD array, inlet, and outlet. The gold catalyst is etched away using wet etching (e.g., based on potassium iodide or aqua regia), plasma etching, or atomic layer etching (e.g., as discussed by TA Green in “Gold Etching for Microfabrication,” Gold Bulletin, Vol. 47, No. 3, 2014, pp. 205-216, the entire contents of which are incorporated herein by reference). In one embodiment, a polymer barrier material is sprayed onto all regions except the SERS “bathtub” region using inkjet printing. In one embodiment, a porous layer is generated by electrochemically etching the silicon in the SERS “bathtub” region using an electric field and an electrolyte composed of HF. In one embodiment, the morphology (porosity, pore size, and pore orientation) of the porous layer is controlled by varying the voltage and / or current density on the wafer, as discussed by Volker Lehmann in "Electrochemistry of Silicon: Instrumentation, Science, Materials and Applications," Wiley-VCHVerlag GmbH, Weinheim, 2002, pp. 1-115, and by Alexey Ivanov in "Silicon Anodization as a Structuring Technique: Literature Review, Modeling and Experiments," 2018, pp. 1-316, the entire contents of which are incorporated herein by reference.

[0050] In another embodiment, an optimized combination of MACE etchants is used, and an electric field is applied after using a polymer coating, such as inkjet and UV-cured acrylate materials, to block all other regions except the SZ region, employing a gold catalyst (e.g., catalyst 805) to generate a porous layer beneath the bathtub, as discussed in Choi et al., "UV NanoimprintLithography," Handbook of Nanofabrication, edited by Gary Wiederrecht, Elsevier Press, October 2009, 310 pages, see pp. 149-181. Alternatively, in the absence of an electric field, an etchant consisting of HF and a strong oxidant, such as nitric acid, can be used to generate a porous silicon layer in the bathtub region using a staining etching technique.

[0051] In one embodiment, after creating a porous region beneath the gold, the gold can be patterned and etched to generate an optimal SERS pattern required for signal enhancement. Exemplary SERS patterns are discussed in Sharma et al.'s "SERS: Materials, Applications and the Future," Materials Today, Vol. 15, Nos. 1-2, January-February 2012, pp. 16-25. This patterning step can be performed using nanoimprint lithography and wet etching steps as described below: (1) After generating a porous region under the bathtub in the SZ part of the wafer, the wafer is cleaned with oxygen plasma or UV ozone cleaner to remove all polymer materials. (2) Coating a thin (less than 10 nm) adhesion layer over the entire wafer, such as the adhesion layer reported in Choi et al., "UV Nanoimprint Lithography," Handbook of Nanofabrication, edited by Gary Wiederrecht, Elsevier Press, October 2009, 310 pages, see pp. 149-181; (3) Imprinting a template containing the desired SERS pattern onto the adhesive layer at the bottom of the "bathtub". The template has the desired SERS pattern on the "countertop" suitable for the bathtub. Once this imprinting step is completed, there will be a residual polymer layer with a thickness of 15 to 40 nanometers under the SERS pattern, while the rest of the wafer is covered by a residual polymer film of at least 75 nanometers or more; (4) Next, perform something similar to Figure 7 and Figures 8A to 8D The residual layer (base coat) etching discussed in the paper is used to etch the residual layer and the adhesion layer, thereby exposing the gold film in the recessed resist areas; (5) Next, the wafer is placed in a gold wet etchant to etch the gold SERS structure at the bottom of the bath; and (6) Finally, the polymer imprint material is removed at various locations to complete the fabrication of the integrated SERS sensor on the porous silicon material in the SZ region. This allows the solvent and buffer to be absorbed into the porous silicon and to sense materials such as exosomes, biomacromolecules, proteins, etc.

[0052] Figure 13 A flowchart illustrating a method for manufacturing a self-aligned column using the MACE process according to an embodiment of the present invention is shown. Figures 14A to 14C The use according to an embodiment of the present invention is described. Figure 13 The steps described above utilize the MACE process to create a cross-sectional view of the self-aligned column.

[0053] refer to Figure 13 , combined Figures 14A to 14C In step 1301, the MACE catalyst 1401 is deposited on the opening portion of the substrate 1402, wherein the opening portion refers to the portion of the substrate 1402 that does not include the pillar 1403 (e.g., a conical pillar), such as... Figure 14A As shown. In one embodiment, this tapered pillar 1403 is generated by a MACE process for DLD array 101. Figure 14A The self-aligned multi-step MACE process shown allows these pillars to be fabricated with specific tapered geometries.

[0054] In step 1302, as Figure 14B As shown, oxide 1404 is deposited and / or grown on pillar 1403, for example, along its sidewalls. In one embodiment, the sidewall oxidation step is performed using common semiconductor oxidation techniques, such as thermal oxidation or exposure to oxygen plasma.

[0055] In step 1303, as Figure 14C As shown, the sidewall oxide 1404 is removed (dissolved) along with a portion of the silicon 1402. For example, in one embodiment, HF vapor or a short BOE impregnation is used to remove the thin walls of the formed oxide 1404.

[0056] Using the principles of the present invention discussed above, trace amounts of nanoparticles in biomarkers and chemical mixtures or water can be effectively detected.

[0057] The description of various embodiments of the present invention is for illustrative purposes and is not intended to be exhaustive or to limit the technology to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is for the purpose of best explaining the principles of the embodiments, their practical application, or improvements to technology found in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A diagnostic chip, comprising: One or more inputs, wherein a sample containing particles of different sizes is introduced into at least one of the one or more inputs; and Multiple separation zones, wherein the sample is pressurized as it passes through the multiple separation zones, each of the multiple separation zones includes a deterministic lateral displacement array, and two or more of the deterministic lateral displacement arrays in the multiple separation zones have different etching depth profiles; The transition portion between adjacent separation zones in the plurality of separation zones includes a gradually changing slope, which is configured to prevent particles from getting stuck at the foot of the step between the adjacent separation zones.

2. The diagnostic chip of claim 1, wherein, The pillars in the deterministic lateral displacement array are manufactured using metal-assisted chemical etching.

3. The diagnostic chip of claim 1, wherein, The pillars in the deterministic lateral displacement array are fabricated using nanoimprint lithography.

4. The diagnostic chip of claim 1, wherein, The deterministic lateral displacement array is used for particle separation.

5. The diagnostic chip according to claim 1, wherein, The columns in the deterministic lateral displacement array are conical.

6. The diagnostic chip according to claim 1, wherein, The pillars in the deterministic lateral displacement array are generated using metal-assisted chemical etching and silicon oxidation.

7. The diagnostic chip according to claim 1, wherein, The ratio of the diameter to the spacing of the columns in the deterministic lateral displacement array is greater than 0.8, wherein the columns are designed to prevent particle blockage in the sample.

8. The diagnostic chip according to claim 1, further comprising: A side barrier array is located within the deterministic lateral displacement array used for particle separation.

9. The diagnostic chip according to claim 1, wherein, The sample includes one of blood, serum, saliva, and urine.

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