# US 10,767,925 B2 · Method for dehydration and critical point drying > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,767,925 B2 - Document ID: US10767925B2 - Status: Granted - Kind: B2 - Application number: 16/228,879 - Filed: 2018-12-21 - Published: 2019-06-27 - Granted: 2020-09-08 - Earliest claimed: 2017-12-22 - Assignees: Safematic Oy - Applicants: safematic GmbH - Inventors: Patrick Capeder; Walter Colleoni; Christof Graf - Web page: https://patentgrep.com/patent/US10767925B2 ## CPC - F26B 3/00: Drying solid materials or objects by processes involving the application of heat (in specific machines or apparatus F26B9/00 - F26B19/00) - F26B 5/005: {by dipping them into or mixing them with a chemical liquid, e.g. organic; chemical, e.g. organic, dewatering aids (F26B3/005 takes precedence; using chemical vapours or gases F26B21/40)} - F26B 9/06: in stationary drums or chambers - F26B 25/22: Controlling the drying process in dependence on liquid content of solid materials or objects - G01N 1/28: Preparing specimens for investigation {including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q}(mounting specimens on microscopic slides G02B21/34; means for supporting the objects or the materials to be analysed in electron microscopes H01J37/20 {; laboratory gas handling apparatus B01L5/00}) - G01N 1/40: Concentrating samples - G01N 2001/4027: {evaporation leaving a concentrated sample} - F26B: DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM (drying devices for combines A01D41/133; racks for drying fruit or vegetables A01F25/12; drying foodstuffs A23; drying hair A45D20/00; body-drying implements A47K10/00; drying household articles A47L; drying gases or vapours B01D; chemical or physical processes for dewatering or like separating liquids from solids B01D43/00; centrifugal apparatus B04; drying ceramics C04B33/30; drying yarns or fabrics in association with some other form of treatment D06C; drying frames for laundry without heating or positive air circulation, domestic laundry-or spin-driers, wringing or hot pressing laundry D06F; furnaces, kilns, ovens F27) - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract A method for dehydration and critical point drying of a sample in a single chamber is introduced, comprising the steps of (a) dehydrating the sample by replacing water by an intermediate fluid, (b) replacing the intermediate fluid by a transitional fluid, (c) pressurising the transitional fluid to or beyond its critical pressure and/or heating the transitional fluid (4 to or beyond its critical temperature, and (d) in response to gradually releasing the pressure, letting the transitional fluid gasify and escape from the sample. In step (a) and/or step (b), a ratio of the fluid to-be-replaced to the replacing fluid is measured and used to control a supply of the replacing fluid. The method reduces consumption of intermediate fluid and/or transitional fluid, making the process more efficient in terms of duration and user interaction while ensuring a high degree of dryness and the integrity of the sample. ## Claims ### Claim 1 A method for dehydration and critical point drying of a sample in a single chamber, the method comprising the steps of: a) dehydrating the sample by replacing water with an intermediate fluid, b) replacing the intermediate fluid with a transitional fluid having a critical temperature and a critical pressure, c) one or more of pressurising the transitional fluid to or beyond said critical pressure and heating the transitional fluid to or beyond said critical temperature, and d) in response to gradually releasing the pressure, letting the transitional fluid gasify and escape from the sample, and wherein one or more of: in step a) a first ratio of the water to the intermediate fluid is measured and used to control a supply of the intermediate fluid; and in step b), a second ratio of the intermediate fluid to the transitional fluid is measured and used to control a supply of the transitional fluid. ### Claim 2 (depends on 1) The method according to claim 1, comprising: a combination of two or more of leaving fluid present inside the chamber at rest, circulating the fluid present inside the chamber, and flushing the chamber with at least one of fresh intermediate fluid in step a) and fresh transitional fluid in step b). ### Claim 3 (depends on 2) The method according to claim 2, wherein the combination is repeated. ### Claim 4 (depends on 1) The method according to claim 1, comprising: one or more of continuing with step b) after step a) in response to the first ratio falling below a predefined limit, and continuing with step c) after step b) in response to the second ratio falling below a second pre-defined limit. ### Claim 5 (depends on 1) The method according to claim 1, comprising: one or more of stopping the supply of the intermediate fluid in step a) in response to the first ratio falling below a third predefined limit, and stopping the supply of the transitional fluid in step b) in response to the second ratio falling below a fourth predefined limit. ### Claim 6 (depends on 1) The method according to claim 1, comprising: sensing a temperature of the intermediate fluid outside the chamber in step a) and, respectively, of the transitional fluid outside the chamber in step b), and a temperature of fluid present inside the chamber. ### Claim 7 (depends on 6) The method according to claim 6, comprising: cooling the fluid present inside the chamber below the temperature of the intermediate fluid in step a), causing the intermediate fluid to stay liquid when entering the chamber, and cooling the fluid present inside the chamber below the temperature of the transitional fluid in step b), causing the transitional fluid to stay liquid when entering the chamber. ### Claim 8 (depends on 7) The method according to claim 7, wherein the temperature of the fluid present inside the chamber is controlled to a temperature level at least 5° C. below the temperature of the intermediate fluid in step a) and at least 5° C. below the temperature of the transitional fluid in step b). ### Claim 9 (depends on 1) The method according to claim 1, comprising: sensing a fill level of fluid present inside the chamber. ### Claim 10 (depends on 1) The method according to claim 1, comprising: heating fluid present inside the chamber to raise a pressure in the chamber and measuring the pressure in the chamber. ### Claim 11 (depends on 1) The method according to claim 1, comprising: sensing a fill level of fluid present inside the chamber, heating the fluid present inside the chamber to raise a pressure in the chamber and measuring the pressure in the chamber, and switching to step b), only if the fill level of the fluid present inside the chamber is equal to or greater than a predefined value in order to immerse the sample in the intermediate fluid, and if a pressure level of the transitional fluid outside the chamber and the pressure in the chamber match within a predefined margin, in order to avoid or reduce a pressure shock. ### Claim 12 (depends on 1) The method according to claim 1, wherein the intermediate fluid is one of ethanol, acetone, isopropanol, amyl acetate, or a solution of one of ethanol, acetone, isopropanol and amyl acetate in water, and the transitional fluid is liquid carbon dioxide. ### Claim 13 (depends on 1) A computer readable product, comprising computer readable code for causing a performance of a method according to claim 1 when operated on a control unit. ### Claim 14 An apparatus to perform dehydration and critical point drying of a sample, comprising: a chamber configured to host the sample, a supply for an intermediate fluid into the chamber to dehydrate the sample by replacing water, a supply for a transitional fluid into the chamber to replace the intermediate fluid, the transitional fluid having a critical temperature and a critical pressure, a sensor configured to measure one or more of a first ratio of the water to the intermediate fluid, and a second ratio of the intermediate fluid to the transitional fluid, a heating element configured to perform critical point drying of the sample, and a control unit configured to control one or more of the supply of intermediate fluid into the chamber depending on the first ratio and the supply of transitional fluid into the chamber depending on the second ratio, control one or more of pressurising the transitional fluid to or beyond said critical pressure and heating the transitional fluid with the heating element to or beyond said critical temperature, and control, in response to gradually releasing the pressure, letting the transitional fluid gasify and escape from the sample. ### Claim 15 (depends on 14) The apparatus according to claim 14, comprising: a pump configured to circulate fluid present inside the chamber. ### Claim 16 (depends on 14) The apparatus according to claim 14, comprising one or more of: a temperature sensor as well as a pressure sensor arranged inside the chamber, a temperature sensor as well as a pressure sensor configured to sense one or more of the intermediate fluid and the transitional fluid outside the chamber, and a cooling element configured to cool fluid present inside the chamber. ### Claim 17 (depends on 14) The apparatus according to claim 14, comprising: a sensor configured to measure a fill level in the chamber for controlling the fill level of the intermediate fluid in such a way that a pressure shock is avoided or reduced when supplying pressurised transitional fluid.