# US 7,745,249 B2 · Multi-scale cantilever structures having nano sized holes and method of preparing the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,745,249 B2 - Document ID: US7745249B2 - Status: Granted - Kind: B2 - Application number: 12/245,940 - Filed: 2008-10-06 - Published: 2010-06-03 - Granted: 2010-06-29 - Earliest claimed: 2005-10-27 - Assignees: Postech Foundation; Postech Academy-Industry Foundation - Inventors: Jung Hyun Lee; Pyung Soo Lee; Kun Hong Lee; Nayoung Shin - Web page: https://patentgrep.com/patent/US7745249B2 ## CPC - B81C 1/0015: {Cantilevers (switches using MEMS H01H1/0036; electrostatic relays using micromechanics H01H59/0009; microelectro-mechanical resonators H03H9/02244)} - G01N 29/036: by measuring frequency or resonance of acoustic waves - G01N 2291/0256: Adsorption, desorption, surface mass change, e.g. on biosensors - B81C: PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS (making microcapsules or microballoons B01J13/02; processes or apparatus specially adapted for the manufacture or treatment of piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/01) - 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 Provided are a multi-scale cantilever structure having nano-sized holes prepared by anodic oxidation and a method of preparing the same. The multi-scale cantilever structure is prepared using anodic oxidation and electro-polishing so that a manufacturing process is simple and a manufacturing cost is inexpensive. In addition, the multi-scale cantilever structure has a porous structure having a plurality of nano-sized holes inside thereof, and thus a surface area of the cantilever structure can be maximized. Therefore, when the cantilever structure is used in a sensor, the sensor can have improved sensitivity and selectivity. ## Claims ### Claim 1 A method of preparing a multi-scale cantilever structure, comprising: forming an alumina layer having a plurality of nano-sized holes by anodic oxidizing an aluminum substrate; forming a first structure by sequentially depositing a metal thin film layer and a photoresist layer on the alumina layer; forming a photoresist layer pattern having a convex cross section by arranging a mask having a pattern of a convex cross section on the first structure and then exposing the photoresist layer to light and developing the photoresist layer; forming a metal thin film layer pattern having a convex cross section by wet etching the metal thin film layer using the photoresist layer pattern as a mask and a metal etching solution to remove the metal thin film layer on a region that is not covered by the pattern; forming a second structure having a convex cross section by wet etching the alumina layer using the metal thin film layer pattern as a mask and an alumina etching solution to remove the alumina layer that is not covered by the metal thin film layer pattern; and forming a cantilever separated from a surface of the first region of the aluminum substrate by electro-polishing the aluminum substrate to remove, by a surface reaction, a top portion of the aluminum substrate in the first region which is not covered by the second structure. ### Claim 2 (depends on 1) The method of preparing the multi-scale cantilever structure of claim 1, wherein an electrolyte used in the anodic oxidation process is an aqueous electrolyte solution of a phosphoric acid, an oxalic acid, a sulfuric acid, a sulfonic acid or a chromic acid. ### Claim 3 (depends on 1) The method of preparing the multi-scale cantilever structure of claim 1, wherein the cantilever is a porous structure comprising nano-sized holes. ### Claim 4 (depends on 3) The method of preparing the multi-scale cantilever structure of claim 3, wherein the nano-sized holes have a hexagonal cross section. ### Claim 5 (depends on 3) The method of preparing the multi-scale cantilever structure of claim 3, wherein the nano-sized holes have a round, triangular or rectangular cross section. ### Claim 6 (depends on 1) The method of preparing the multi-scale cantilever structure of claim 1, further comprising removing the photoresist layer and forming a nanobead layer, a cavitand receptor layer, a thin polymeric film layer, a metal oxide thin film layer, an organism receptor layer or a self-assembly monolayer (SAM) on the metal thin film layer, after the cantilever is formed. ### Claim 7 (depends on 1) The method of preparing the multi-scale cantilever structure of claim 1, further comprising filling the nano-sized holes with a predetermined material, after the alumina layer is formed. ### Claim 8 (depends on 7) The method of preparing the multi-scale cantilever structure of claim 7, wherein the predetermined material is metal, metal oxide, conductive polymer, a magnetic material, a piezoelectric material, a fluorescent material, a light emitting material, a carbon nanotube (CNT), nanowire, DNA or a stem cell. ### Claim 9 (depends on 1) The method of preparing the multi-scale cantilever structure of claim 1, wherein the metal thin film layer is an aluminum thin film layer. ### Claim 10 (depends on 1) The method of preparing the multi-scale cantilever structure of claim 1, wherein the metal etching solution is an aluminum etching solution. ### Claim 11 (depends on 10) The method of preparing the multi-scale cantilever structure of claim 10, wherein the aluminum etching solution is a solution comprising H3PO4, H2O, CH3COOH and HNO3 in a mass ratio of 16:2:1:1. ### Claim 12 (depends on 1) The method of preparing the multi-scale cantilever structure of claim 1, wherein the alumina etching solution is 5 weight % of a H3PO4 solution. ### Claim 13 (depends on 1) The method of preparing the multi-scale cantilever structure of claim 1, further comprising exposing nano-sized holes of the cantilever by removing the photoresist layer using an organic solvent, and performing wet etching to remove the metal thin film layer after the second structure having a convex cross section is formed. ### Claim 14 (depends on 1) The method of preparing the multi-scale cantilever structure of claim 1, wherein an aluminum etching solution used in the electro-polishing is a solution comprising a perchloric acid and ethanol in a volume ratio of 1:4. ### Claim 15 (depends on 1) The method of preparing the multi-scale cantilever structure of claim 1, further comprising removing the photoresist layer and the metal thin film layer after the second structure having a convex cross section is formed, and removing a barrier layer disposed on a lower portion of the alumina using wet etching after the cantilever is formed to thus form a cantilever having a membrane structure.