# US 10,870,781 B2 · Compositions and methods for probing adhesive interfaces > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,870,781 B2 - Document ID: US10870781B2 - Status: Granted - Kind: B2 - Application number: 15/942,245 - Filed: 2018-03-30 - Published: 2019-10-03 - Granted: 2020-12-22 - Earliest claimed: 2018-03-30 - Assignees: The Boeing Company - Applicants: The Boeing Company - Inventors: Om Prakash; Megha Sahu - Web page: https://patentgrep.com/patent/US10870781B2 ## CPC - C09J 9/00: Adhesives characterised by their physical nature or the effects produced, e.g. glue sticks (C09J7/00 takes precedence) - C09J 5/06: involving heating of the applied adhesive - C09J 11/06: organic - G06T 7/001: {using an image reference approach} - C09J 2463/00: Presence of epoxy resin - G06T 2207/30108: Industrial image inspection - G06T 2207/30208: Marker matrix - C09J: ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES (preparation of glue or gelatine C09H) - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL ## Abstract Systems and methods for monitoring the health of an adhesive interface include the formation of an adhesive bond using an adhesive system incorporating molecular-scale magnetic markers covalently attached to polymer components, acquisition of images representing the distribution of magnetic markers within the adhesive bond at a first time and at a later time, and comparison of the images to detect displacement of the magnetic markers between the first time and the later time. The covalent link between the magnetic markers and the adhesive polymer components locks the magnetic markers in place as long as the adhesive bond remains healthy, so displacement of the magnetic markers between the first time and the later time indicates the presence of a bond defect. The images may be acquired using magnetic particle imaging and compared using digital image correlation. Chemical compositions for the magnetic markers are disclosed. ## Claims ### Claim 1 A method for joining parts, comprising: covalently linking a plurality of magnetic markers to an adhesive polymer component; applying the adhesive polymer component to an interface space between a first surface and a second surface; curing the adhesive polymer component to form a cured adhesive bond between the first and second surfaces; wherein the magnetic markers are randomly distributed and locked in a random spatial orientation within the cured adhesive bond. ### Claim 2 (depends on 1) The method of claim 1, wherein the cured adhesive bond includes location-specific indicia. ### Claim 3 (depends on 2) The method of claim 2, wherein the location-specific indicia includes distinctive random distribution of the magnetic markers. ### Claim 4 (depends on 1) The method of claim 1, wherein the linking step is carried out prior to the curing step. ### Claim 5 (depends on 1) The method of claim 1, wherein the magnetic marker includes a charge-transfer salt comprising: (a) a plurality of organometallic charge-transfer complexes having the formula M(TCNE)x where M is selected from the group consisting of Fe, Co, Ni, Mn(porphyrin), and [Fe(C5Me5)2]; and x is 1-4; or (b) a spinel structure having the formula J[Fe2O4] where J is selected from the group consisting of Cu, Ni, Mn, and Mg. ### Claim 6 (depends on 1) The method of claim 1, further comprising: detecting structural changes in the adhesive bond over time. ### Claim 7 (depends on 6) The method of claim 6, wherein the detecting step includes acquiring images of the adhesive bond using magnetic particle imaging. ### Claim 8 (depends on 6) The method of claim 6, wherein the detecting step includes correlating digital images of the bond acquired at different times. ### Claim 9 A method of monitoring a characteristic of an adhesive bond over time, comprising: creating an adhesive bond between two structures, wherein the adhesive bond includes a plurality of randomly distributed magnetic markers covalently attached to a polymer component; applying a magnetic field by a mobile device spaced away from the adhesive bond, and configured to induce a change in magnetization of the magnetic markers; recording by the mobile device an induced voltage of the magnetic markers in a magnetic field free region; acquiring a first digital image of the adhesive bond by the mobile device using magnetic particle imaging at a first time point; acquiring a second digital image of the adhesive bond by the mobile device using magnetic particle imaging at a second time point; and comparing the second digital image to the first digital image. ### Claim 10 (depends on 9) The method of claim 9, wherein the creating step includes applying an adhesive system incorporating a magnetic marker covalently attached to a polymer component. ### Claim 11 (depends on 10) The method of claim 10, wherein the magnetic marker is about 1 mg/Kg concentration in the adhesive bond. ### Claim 12 (depends on 9) The method of claim 9, wherein the adhesive bond includes location-specific indicia, further comprising: rotating one of the first and second digital images until the location-specific indicia in the digital images have the same orientation. ### Claim 13 (depends on 9) The method of claim 9, wherein the acquiring steps are performed in situ. ### Claim 14 (depends on 9) The method of claim 9, wherein the acquiring steps are performed with the mobile device configured for movement throughout an aircraft. ### Claim 15 (depends on 14) The method of claim 14, wherein the mobile device is configured to be manually held and operated. ### Claim 16 An adhesive system, comprising: an epoxy resin comprising polymers having epoxide groups; a curing agent formulated for combining with the resin, and causing crosslinking between polymers in the resin; and a plurality of magnetic markers configured for covalent attachment to the polymer, wherein the magnetic markers are randomly distributed and locked in a random spatial orientation within the adhesive system and form a subset of magnetic markers disposed in a plurality of patterns. ### Claim 17 (depends on 16) The adhesive system of claim 16, wherein the magnetic marker is included in the epoxy resin prior to combining the resin with the curing agent. ### Claim 18 (depends on 16) The adhesive system of claim 16, wherein the magnetic marker is provided in the curing agent. ### Claim 19 (depends on 16) The adhesive system of claim 16, wherein the magnetic marker includes a charge-transfer salt that comprises: (a) a plurality of organometallic charge-transfer complexes having the formula M(TCNE)x where M is selected from the group consisting of Fe, Co, Ni, Mn(porphyrin), and [Fe(C5Me5)2] where x is 1-4; or (b) a spinel structure having the formula J[Fe2O4] where J is selected from the group consisting of Cu, Ni, Mn, and Mg. ### Claim 20 (depends on 12) The method of claim 12, wherein the rotating step is carried out in three dimensions.