# US 2022/0276201 A1 · Ion mobility spectrometer with center rod > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2022/0276201 A1 - Document ID: US20220276201A1 - Status: Published application - Kind: A1 - Application number: 17/698,048 - Filed: 2022-03-18 - Published: 2022-09-01 - Earliest claimed: 2018-07-10 - Assignees: Ion Dx, Inc. - Applicants: Ion Dx, Inc. - Inventors: W. Henry Benner; Michael J. Bogan; Ben Aguilar - Web page: https://patentgrep.com/patent/US20220276201A1 ## CPC - G01N 27/622: Ion mobility spectrometry - 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 Apparatuses and methods are described for determining properties of ions travelling through a gas under the influence of an electric field. The apparatuses and methods can be understood to provide measurements of the electrical mobility of ions as useful for determining the electrical mobility constant Ko of electrosprayed substances, such as proteins. The apparatuses and methods relate to the scientific discipline of ion mobility spectrometry. Modules connected to ion mobility spectrometers provide stress to substances for the purpose of investigating, for example, the thermal stability of proteins. One form of the technology includes a tubular spectrometer body having an electrically conductive inner wall; a rod positioned along the longitudinal center of the body and electrodes positioned on, but electrically isolated from, the inner wall, where the ratio of the radius of the tubular spectrometer body to the ratio of the radius of the rod is at least 20. ## Claims ### Claim 1 An apparatus, comprising: a tubular spectrometer body having an electrically conductive inner wall; a rod positioned along the longitudinal center of said tubular spectrometer body; and one or more ring electrodes positioned on, but electrically isolated from, said inner wall. ### Claim 2 (depends on 1) The apparatus of claim 1, further comprising means for applying a voltage between said rod and said inner wall. ### Claim 3 (depends on 2) The apparatus of claim 2, wherein said voltage is a ramped voltage. ### Claim 4 (depends on 1) The apparatus of claim 1, further comprising means for flowing gas through said spectrometer body. ### Claim 5 (depends on 1) The apparatus of claim 1, further comprising means for generating and introducing gas-phase ions in a flow of gas into said spectrometer body. ### Claim 6 (depends on 1) The apparatus of claim 1, further comprising means for measuring an output voltage from at least one of said electrodes, wherein said output voltage is proportional to ion current. ### Claim 7 (depends on 1) The apparatus of claim 1, wherein said electrodes are operatively positioned within said tube to detect specific ions. ### Claim 8 (depends on 2) The apparatus of claim 2, wherein said means for applying a voltage is configured such that said ions will be repelled from said rod toward said one or more electrodes. ### Claim 9 (depends on 1) The apparatus of claim 1, further comprising means for generating an ion mobility spectrum by recording an ion current while voltage applied to said center rod is ramped. ### Claim 10 (depends on 1) The apparatus of claim 1, further comprising means for generating an ion mobility spectrum in which the widths of the ion mobility peaks are used to determine the variation of the size of an ion. ### Claim 11 (depends on 1) The apparatus of claim 1, further comprising means for generating an ion mobility spectrum by recording an ion current during the time the voltage applied to the center rod is ramped and the sample is heated. ### Claim 12 (depends on 1) The apparatus of claim 1, further comprising means for determining the thermal stability of a substance by monitoring the ion current for the substance while the sample is heated. ### Claim 13 (depends on 1) The apparatus of claim 1, further comprising the use of image recognition software and feedback control to provide stable electrospray. ### Claim 14 (depends on 1) The apparatus of claim 1, further comprising a means for controlling a charge-reduction process by providing a physical restriction between the electrospray source and a polonium source. ### Claim 15 (depends on 1) The apparatus of claim 1, further comprising a means for producing an electric field that decreases logarithmically in strength between a center rod and a surrounding cylindrical metal cylinder. ### Claim 16 (depends on 1) The apparatus of claim 1, further comprising a means for producing the body of the spectrometer as the combination of two half-pipes. ### Claim 17 (depends on 1) The apparatus of claim 1, further comprising a means for automated sample analysis. ### Claim 18 A method, comprising: providing a tubular spectrometer body having an electrically conductive inner wall; providing a rod positioned along the longitudinal center of said tubular spectrometer body; providing one or more ring electrodes positioned on, but electrically isolated from, said inner wall; directing a flow of gas-phase ions into said spectrometer body while applying a voltage between said rod and said inner wall; and measuring an output voltage from at least one of said electrodes. ### Claim 19 (depends on 18) The method of claim 18, wherein said voltage is a ramped voltage. ### Claim 20 (depends on 18) The method of claim 18, further comprising flowing gas through said spectrometer body, wherein said gas-phase ions flow in said flowing gas. ### Claim 21 (depends on 18) The method of claim 18, further comprising measuring an output voltage from at least one of said electrodes, wherein said output voltage is proportional to ion current. ### Claim 22 (depends on 18) The method of claim 18, wherein said electrodes are operatively positioned within said tube to detect specific ions. ### Claim 23 (depends on 18) The method of claim 18, wherein said voltage is applied such that said ions will be repelled from said rod toward said one or more electrodes. ### Claim 24 (depends on 18) The method of claim 18, further comprising generating an ion mobility spectrum by recording an ion current determined from said output voltage. ### Claim 25 (depends on 18) The method of claim 18, further comprising generating an ion mobility spectrum by recording an ion current determined from said output voltage while voltage applied to said center rod is ramped. ### Claim 26 (depends on 18) The method of claim 18, further comprising generating an ion mobility spectrum from said output voltage and determining the variation of the size of an ion from the widths of the ion mobility peaks. ### Claim 27 (depends on 18) The method of claim 18, further comprising generating an ion mobility spectrum from said output voltage by recording an ion current during the time said voltage applied to said center rod is ramped and a sample is heated. ### Claim 28 (depends on 18) The method of claim 18, further comprising means for determining the thermal stability of a substance by monitoring the ion current for a substance while the sample is heated. ### Claim 29 (depends on 18) The method of claim 18, further comprising using image recognition software and feedback control to provide stable electrospray. ### Claim 30 (depends on 18) The method of claim 18, further comprising a controlling a charge-reduction process by providing a physical restriction between an electrospray source and a polonium source. ### Claim 31 (depends on 18) The method of claim 18, further comprising producing an electric field that decreases logarithmically in strength between said center rod and a surrounding cylindrical metal cylinder located within said tubular spectrometer body.