Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
  • G01N15/06—Investigating concentration of particle suspensions
  • G01N15/0606—Investigating concentration of particle suspensions by collecting particles on a support
  • G01N15/0612—Optical scan of the deposits
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/36—Removing material
  • B23K26/38—Removing material by boring or cutting
  • B23K26/382—Removing material by boring or cutting by boring
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N1/00—Sampling; Preparing specimens for investigation
  • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
  • G01N1/40—Concentrating samples
  • G01N1/4077—Concentrating samples by other techniques involving separation of suspended solids
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
  • G01N15/06—Investigating concentration of particle suspensions
  • G01N15/0606—Investigating concentration of particle suspensions by collecting particles on a support
  • G01N15/0618—Investigating concentration of particle suspensions by collecting particles on a support of the filter type
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
  • G01N15/06—Investigating concentration of particle suspensions
  • G01N15/0606—Investigating concentration of particle suspensions by collecting particles on a support
  • G01N15/0618—Investigating concentration of particle suspensions by collecting particles on a support of the filter type
  • G01N15/0625—Optical scan of the deposits
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N1/00—Sampling; Preparing specimens for investigation
  • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
  • G01N1/40—Concentrating samples
  • G01N1/4077—Concentrating samples by other techniques involving separation of suspended solids
  • G01N2001/4088—Concentrating samples by other techniques involving separation of suspended solids filtration
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
  • G01N2015/0042—Investigating dispersion of solids
  • G01N2015/0053—Investigating dispersion of solids in liquids, e.g. trouble

Definitions

• the present invention relates to a filter substrate for filtering and optical characterization of microparticles.
• the filter substrate comprises a wafer having a thickness of at least 100 ⁇ m and a transmittance of at least 10% for radiation in the wavelength range of 2500 nm to 15000 nm.
• the surface of the front side and / or the surface of the backside of the wafer is completely or partially with a wafer antireflection
• the present invention relates to a method for producing the Filter substrate according to the invention and the use of the erfindungsge MAESSEN filter substrate.
• Microplastic particles in aqueous systems or their characterization with optical spectral methods are of great importance for environmental analysis, health and occupational safety.
• optical particle analysis with spectral methods requires a broadband transparency of the filter substrates down to the near / middle infrared range (FTIR) and / or broadband reduced substrate reflection (Raman, fluorescence spectroscopy).
• FTIR near / middle infrared range
• Raman broadband reduced substrate reflection
• Physico-chemical work-up steps are necessary to reduce the disturbing, inorganic and organic concomitant properties of the filter cake (inter alia density separation with various saturated salt solutions or oxidative treatment with H2O2) ⁇
• the use of various treatment steps must not impair the functionality of the filter material. This must also be ensured by the use of sanitation steps.
• fractionated filtrations are used with various plastic-based filters (including acetate, Teflon), woven or sintered metal materials, or inorganic fiber or pore filters (alumina, glass fibers). Due to the problem of completeness ended transfer of samples from the filter materials on optical sample holder analysis would be advantageous directly on the filter. In addition, direct detection (also, for example, after the physicochemical treatment steps) would minimize the problem of sample contamination.
• plastic-based filters including acetate, Teflon
• woven or sintered metal materials including woven or sintered metal materials, or inorganic fiber or pore filters (alumina, glass fibers). Due to the problem of completeness ended transfer of samples from the filter materials on optical sample holder analysis would be advantageous directly on the filter. In addition, direct detection (also, for example, after the physicochemical treatment steps) would minimize the problem of sample contamination.
• direct detection also, for example, after the physicochemical treatment steps
• the listed materials are problematic in terms of upset
• the invention thus provides a filter substrate for filtering and optical characterization of microparticles.
• the filter substrate comprises a wafer having a thickness of at least 100 pm and a transmissivity of at least 10% for radiation in the wavelength range from 2500 nm to 15000 nm.
• the surface of the front side and / or the Surface of the back of the wafer completely or partially provided with an antireflection layer, which prevents optical reflection of radiation in the Wel lenaten Scheme from 200 nm to 10,000 nm.
• the Wa fer at least partially filter holes with a diameter of 1 pm to 5 mm.
• Microparticles are understood as meaning particles with a diameter of 1 ⁇ m to 5,000 ⁇ m.
• the transmittance can be determined according to DIN 5036-3 or according to CIE 130-1998.
• the filter holes located in the wafer can be used as a filter substrate, since the medium to be filtered (liquid or gaseous) is rinsed through the filter holes, while microparticles located in the medium to be filtered get caught on the wafer.
• the filter holes may be e.g. be introduced by laser drilling into the wafer. As a result, variable hole diameter and variable hole geometries can be obtained.
• the filter sub strate is therefore particularly suitable for use in cascade filter systems for sample volumes of up to several liters of medium (liquid or gas).
• the filter holes each extend from the front side of the filter substrate or the wafer to the rear side of the filter substrate or the wafer. In other words, the filter holes each pass completely through the wafer or the filter substrate, so that the medium to be filtered (liquid or gas) can pass through the filter through the filter holes.
• the filter holes which run in a region of the wafer whose surfaces are provided with the antireflection layer, also pass through the antireflection layer. The filter holes are thus exposed and are not obscured by the antireflection layer. In other words, the antireflective layer is not disposed over the filter holes.
• the filter substrate can be used for filtering the microparticles, for example in a suitable holder.
• the wafer can be mechanically supported by a reinforcing structure also inserted into the holder.
• This reinforcing structure may be, for example, a coarse-meshed openwork, eg made of metal or specific plastic.
• a wafer is, according to the general definition, a thin disk of any shape.
• the wafer may have a circular or square basic shape.
• the wafer has a circular basic shape.
• the diameter of the wafer may be e.g. 10 mm to 1000 mm. With a minimum thickness of 100 pm, the wafer has sufficient stability to be used as a filter substrate for filtering microparticles.
• Wafers are commonly used as a substrate for electronic devices in semiconductor technology.
• a sol cher wafer serves as a filter substrate.
• Wafers are available in suitable thicknesses and materials, so that the requirements for stability and optical transparency of the filter substrate can be easily met.
• wafers can be provided with filter holes in a simple manner (for example by means of laser drilling).
• applying an antireflective layer is possible (e.g., by incorporation of nanostructuring or application of a nanostructured coating). A wafer is thus outstandingly suitable as a basic element of the filter substrate according to the invention.
• the filter substrate Due to the high transmittance in the wavelength range of 2500 nm to 15000 nm and due to the antireflection layer, the filter substrate is not only suitable for filtering the microparticles but also as a substrate for optical characterization of the microparticles, with a very high quality measurement is achieved.
• the high degree of transmittance ensures that a sufficient amount of radiation can transmit through the substrate in order to ensure a very good measurement quality in transmission measurements (such as FTIR).
• the antireflection layer prevents the optical reflection of radiation in the wavelength range of 200 nm to 10,000 nm. In this way, the signal-to-noise ratio in reflection measurements (such as Raman measurements) significantly improved, resulting in a very good quality measurement in these Measurements leads.
• the filter substrate according to the invention can be used so well for filtering as well as for the optical characterization of the microparticles.
• the optical characterization can be done directly on the filter substrate, so that a transfer from the filter substrate to an optical sample holder is no longer necessary. In egg nem such carryover occurring problems can thus be avoided who the.
• the filter substrate according to the invention thus allows both a filtering of microparticles and a subsequent opti cal characterization of the microparticles on the filter substrate with a very high quality measurement.
• the surface of the front side and / or the back side of the wafer can be provided with an antireflection coating in full or only in regions.
• the filter substrate has at least one region without an antireflection layer on which transmission measurements (eg FTIR) can be performed and at least an area with an antireflection layer on which reflection measurements (eg Raman) can be performed.
• transmission measurements eg FTIR
• reflection measurements eg Raman
• an antireflection layer is arranged on the entire surface of the front side and / or the back side of the wafer. It should be noted, however, that the area above the filter holes does not belong to the surface of the wafer. In the Consequently, even in the event that the surface of the front side and / or the back side of the wafer is completely provided with an antireflection layer, the antireflection layer is not arranged above the filter holes. Here again, the filter holes are free and are not covered by the anti-reflection coating.
• the antireflection layer should have a transmittance of at least 10% for radiation in individual sections from the wavelength range of 2500 nm to 15000 nm.
• the antireflection layer could, for example, be designed as a spectral filter which influences both the reflection and the transmission only in selected wavelength ranges.
• the antireflection layer prevents the optical reflection of at least 90%, preferably of at least 99%, more preferably of more than 99%, of the radiation impinging on it in the wavelength range from 200 nm to 10000 nm.
• a preferred embodiment of the filter substrate according to the invention is characterized in that the antireflection layer is a nanostructuring introduced into the surface of the wafer or a nanostructured coating applied to the surface of the wafer.
• the antireflection layer is a nanostructuring introduced into the surface of the wafer or a nanostructured coating applied to the surface of the wafer.
• Such nanostructures and nanostructured coatings are particularly suitable as antireflection layers, since in the desired wavelength range no radiation or almost no radiation is reflected.
• the nanostructuring can be a local nanostructuring, which is introduced by means of plasma etching, for example.
• the nanostructured-structured coating may be, for example, the coating Nanoblack ® from ACKTAR.
• the wafer has a thickness greater than 100 pm, preferably greater than 250 pm, particularly preferably greater than 500 pm.
• a higher thickness of the wafer leads to a higher stability of the filter substrate. It can then be used eg for even stronger currents for filtering.
• the filter substrate has a reinforcing structure for the mechanical stabilization of the wafer.
• This reinforcing structure may be e.g. around a roughly perforated base, e.g. made of metal or specific plastic. Due to the reinforcing structure, the wafer is supported and thus stabilized even better.
• the reinforcing structure may be used together with the filter substrate in a geeigne te holder. Due to the better mechanical stabilization due to the reinforcing structure, the filter substrate can be used in even stronger flows, e.g. in waters with stronger current, who used the.
• a further preferred embodiment of the filter substrate according to the invention is characterized in that the wafer is a silicon wafer.
• the water preferably has a degree of doping of at most 10 18 atoms / cm 3 , more preferably of at most 10 17 atoms / cm 3 .
• silicon wafers have high mechanical stability and, on the other hand, high optical transparency in the range of 4000 to 600 cm 1 relevant for FTIR microscopy.
• silicon wafers are stable over reasonable rilisationsclar Ste, with no influence by the use of saturated salt solutions (such as ZnCl 2, NaCl, CaCl 2) or oxidative Behandlun gene with H 2 0 2 takes place.
• Silicon wafers are therefore particularly suitable as a basic element of the filter substrate according to the invention.
• the optical transparency or the transmittance of the wafer can be increased, whereby the measurement quality in Transmissi ons horren increases even further.
• Fil tersubstrats the number of filter holes is at least 100, preferably at least 10,000, more preferably at least 1000000. Such a high number of filter holes, a particularly effective and fast le filtering can be achieved.
• Another preferred embodiment is characterized in that the filter holes
• a diameter of 1 miti to 4000 miti preferably from 1 miti to 2500 miti, more preferably from 1 miti to 1000 miti, very particularly preferably from 1 miti to 500 miti, have, and / or at least partially with a density of 1 filter hole per cm 2 to 1,000,000 filter holes per cm 2 , preferably with a density of 100 filter holes per cm 2 to 10,000 filter holes per cm 2 , are arranged in the tersubstrat Fil, and / or
• the filter holes can all have the same diameter and / or the same geometry. Alternatively, however, the filter holes may also have different diameters and / or different geometries. Also, the areas with filter holes on the wafer can be subdivided into subregions that differ from one another by the density of filter holes per cm 2 . Thus, there can be areas of high density and areas of low density of filter holes per cm 2 on the wafer.
• the filter holes can be introduced into the wafer by means of laser drilling.
• Laser drilling enables the simple and cost-effective production of variable filter holes> 1 pm in a variable arrangement and geometry, as well as with acceptable filter surfaces and mechanical stability.
• the filter substrate is therefore particularly suitable for use in Kaskadenfil tersystemen for sample volumes of up to several liters of medium (liquid or gas).
• Filter holes in the wafer produced by laser drilling have characteristic damage due to laser ablation.
• the filter holes produced in the wafer by means of laser drilling thus differ from otherwise prepared filter holes.
• the production of the filter holes by laser drilling can be proven by microanalyses.
• the present invention also relates to a method for producing a filter substrate according to one of the preceding claims, in which in a wafer with a thickness of 100 .mu.m and a transmittance of at least 10% for radiation in the wavelength range of 2500 nm to 15000 nm at least partially filter holes with a Diameter from 1 pm to 5 mm are introduced, and the surface of the front side and / or the surface of the back of the wafer completely or area wise with an antireflection layer is provided, the optical reflection of radiation in the wavelength range of 200 nm to 10,000 nm prevented.
• the method thus comprises two main steps, namely, on the one hand Ver see the surface of the wafer with the antireflection layer and on the other hand, the introduction of the filter holes in the wafer.
• These two steps can be done in any order.
• first the wafer can be provided with the antireflection layer, in which case subsequently the filter holes are introduced into the wafer.
• the filter holes in this case are then introduced so that they run through the entire thickness of the wafer or the filter substrate including the antireflection layer - if this is present in the region of the respective filter hole.
• first the filter holes can be introduced into the wafer, in which case the wafer is then provided with the antireflection coating. In this case, the application of the antireflection layer takes place so that the filter holes are exposed and are not covered by the antireflection layer.
• the filter substrate is therefore particularly suitable for use in cascade filter systems for
• the front side and / or the back side of the wafer is provided with the antireflection layer by introducing a nanostructure into the surface of the wafer or by applying a nano-structured coating to the surface of the wafer.
• a structured coating is first applied to the surface of the wafer, in which case the filter holes are subsequently introduced into the wafer.
• the filter holes are in this case then introduced so that they strate through the entire thickness of the wafer or the Filterub including the antireflection layer - if this is present in the region of the respec conditions filter hole - run.
• the filter holes are introduced into the wafer, in which case then a nanostructuring is introduced into the surface of the wafer.
• the application of the antireflection layer thus takes place so that the filter holes are exposed and are not covered by the antireflection layer.
• the generation of the antireflection layer preferably takes place before or after the introduction of the filter holes.
• a further preferred variant of the method according to the invention is characterized in that the wafer is provided with a reinforcing structure to be ner mechanical reinforcement.
• the wafer and the reinforcing structure are placed in a common holder is inserted.
• the reinforcing structure may be e.g. around a roughly perforated underlay, e.g. made of metal or specific plastic.
• the present application also relates to the use of the inventions to the invention filter substrate for filtering microparticles and the closing optical characterization of the microparticles on the filter substrate by transmission spectroscopy, preferably IR spectroscopy, eg FTIR spectroscopy, and / or reflection spectroscopy, preferably Raman spectroscopy ,
• the filter substrate according to the invention finds application in Kaskadenfiltersys systems for environmental monitoring of the entry paths of micro plastic in flowing waters.
• IR, Raman, chemometric data evaluation IR, Raman, chemometric data evaluation.
• the filter substrate comprises a wafer 1 with a thickness of at least 100 ⁇ m and a transmittance of at least 10% for radiation in the wavelength range from 2500 nm to 15000 nm.
• the wafer 1 is a silicon wafer, softening a maximum doping level 10 17 atoms / cm 3 .
• the surface of the front side of the wafer 1 is provided in regions with an antireflection layer 2, which prevents optical reflection of radiation in the wavelength range of 200 nm to 10,000 nm. It is an antireflective layer that prevents the optical reflection of more than 99% of the radiation impinging on it in the wavelength range from 200 nm to 10,000 nm.
• the wafer 1 has at least partially filter holes 3 with a diameter of 1 .mu.m to 5 mm.
• the filter holes 3 are introduced by means of laser drilling and each form a straight channel which is perpendicular to the front and the back of the wafer 1.
• the medium to be filtered 4 (liquid or gas) pass through the filter holes 3, wherein the microparticles contained in the medium 5 get stuck on the front side of the filter substrate.
• the optical characterization of the microparticles can take place directly on the filter substrate, the microparticles 5 being irradiated with light 6.
• the optical characterization can take place by means of transmission measurement (eg FTIR). Due to the high transmissivity of the wafer, much of the light can pass through the wafer. The transmitted light 7 can then be analyzed. The high transmittance of the wafer results in a very good measurement quality.
• the optical characterization can also take place by means of reflection measurements (for example Raman).
• the incident light 6 strikes the microparticles 5 and is reflected.
• the reflected light 8 can then be analyzed. Due to the antireflection layer 2, a very good signal-to-noise ratio is obtained, resulting in a very good measurement quality.
• FIG. 2 shows a second embodiment of the filter substrate according to the invention and its use is shown schematically.
• This second embodiment differs from the above-described first embodiment only in that the surface of the front surface of the wafer 1 is completely provided with the antireflective layer 2. Otherwise, the filter substrates of both embodiments are identical.
• the optical characterization at each point of the wafer 1 and the filter substrate by means of reflection measurements can take place.
• the incident light 6 strikes the microparticles 5 and is reflected.
• the reflected light 8 can then analyzed who the. Due to the antireflection layer 2, a very good signal-to-noise ratio is obtained, resulting in a very good measurement quality.
• the optical characterization can in principle also be carried out by means of transmission measurement (eg FTIR) (not shown in FIG. 2).
• transmission measurement eg FTIR
• the antireflection layer should have a transmittance of at least 10% for radiation in the wavelength range from 2500 nm to 15000 nm.
• Si filter substrates (thickness 150 ⁇ m) were produced by laser drilling in polished silicon wafers.
• a laser process was used with the following parameters: wavelength 532 nm, pulse duration 8 ns, repetition rate 50 kHz, power 3 W.
• variable hole structures with diameters in the ns-laser can be used Realize range of a few millimeters to about 50 pm (see Figure 3). Smaller filter holes have already been produced with ultra short pulse lasers and / or electrochemical etching processes.
• FIG. 3 shows in a) an incident-light microscopy image of an Si filter for the particle size class 3000 pm (all particles larger than 3000 pm are collected in this filter). In b) a transmitted light microscopy image of a filter for the particle size class 30 pm is shown.
• an antireflection layer can be easily produced by sputter deposition methods.
• an SiN x layer is deposited with the optical thickness of l / 4, which performs interference to a reduced reflection in the wavelength l.
• broadband antireflection layers can be produced by a nanostructuring (black-silicon) with plasma etching processes.
• the layer deposition can be done before or after the introduction of the filter holes in the Si wafer.
• the process sequence layer deposition / laser drilling depends on the required precision of the hole diameter and the respective deposition process. For conformal deposition methods and small hole diameters, antireflective layer fabrication results in more precise hole geometries.

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• 2018
  • 2018-04-12 DE DE102018205529.7A patent/DE102018205529A1/de active Pending
• 2019
  • 2019-04-11 CN CN201980025363.1A patent/CN112041656A/zh active Pending
  • 2019-04-11 WO PCT/EP2019/059275 patent/WO2019197542A1/de active Application Filing
  • 2019-04-11 US US17/045,976 patent/US11879823B2/en active Active
  • 2019-04-11 KR KR1020207032743A patent/KR20210015783A/ko unknown
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