Template-Stripped Multifunctional Wedge and Pyramid Arrays for Magnetic Nanofocusing and Optical Sensing

Shailabh Kumar; Timothy W. Johnson; Christopher K. Wood; Tao Qu; Nathan J. Wittenberg; Lauren M. Otto; Jonah Shaver; Nicholas J. Long; Randall H. Victora; Joshua B. Edel; Sang Hyun Oh

doi:10.1021/acsami.5b12157

Template-Stripped Multifunctional Wedge and Pyramid Arrays for Magnetic Nanofocusing and Optical Sensing

Shailabh Kumar, Timothy W. Johnson, Christopher K. Wood, Tao Qu, Nathan J. Wittenberg, Lauren M. Otto, Jonah Shaver, Nicholas J. Long, Randall H. Victora, Joshua B. Edel, Sang Hyun Oh

Electrical and Computer Engineering

Research output: Contribution to journal › Article › peer-review

13 Scopus citations

Abstract

We present large-scale reproducible fabrication of multifunctional ultrasharp metallic structures on planar substrates with capabilities including magnetic field nanofocusing and plasmonic sensing. Objects with sharp tips such as wedges and pyramids made with noble metals have been extensively used for enhancing local electric fields via the lightning-rod effect or plasmonic nanofocusing. However, analogous nanofocusing of magnetic fields using sharp tips made with magnetic materials has not been widely realized. Reproducible fabrication of sharp tips with magnetic as well as noble metal layers on planar substrates can enable straightforward application of their material and shape-derived functionalities. We use a template-stripping method to produce plasmonic-shell-coated nickel wedge and pyramid arrays at the wafer-scale with tip radius of curvature close to 10 nm. We further explore the magnetic nanofocusing capabilities of these ultrasharp substrates, deriving analytical formulas and comparing the results with computer simulations. These structures exhibit nanoscale spatial control over the trapping of magnetic microbeads and nanoparticles in solution. Additionally, enhanced optical sensing of analytes by these plasmonic-shell-coated substrates is demonstrated using surface-enhanced Raman spectroscopy. These methods can guide the design and fabrication of novel devices with applications including nanoparticle manipulation, biosensing, and magnetoplasmonics.

Original language	English (US)
Pages (from-to)	9319-9326
Number of pages	8
Journal	ACS Applied Materials and Interfaces
Volume	8
Issue number	14
DOIs	https://doi.org/10.1021/acsami.5b12157
State	Published - Apr 27 2016

Bibliographical note

Funding Information:
This work was supported by grants from the National Science Foundation (NSF CAREER Award for S.K., N.J.W., L.M.O., S.H.O.; NSF Graduate Research Fellowship for L.M.O.), Seagate Technology through the Center for Micromagnetics and Information Technologies (MINT) at the University of Minnesota (J.S., T.Q., S.H.O., R.H.V.), EPSRC (J.B.E., C.K.W., and N.J.L.), ERC (J.B.E.), and the MnDrive Initiative (N.J.W. and S.H.O). S.H.O. also acknowledges the NSF program: Research Opportunities in Europe for NSF CAREER awardees (DBI 1338654), which supported this collaboration between the University of Minnesota and Imperial College London. S.K. was supported by the Doctoral Dissertation Fellowship from the University of Minnesota. Device fabrication was performed at the Minnesota Nano Center at the University of Minnesota, which receives support from the NSF through the National Nanotechnology Coordinated Infrastructure. Computational modeling using COMSOL Multiphysics was performed through the University of Minnesota Supercomputing Institute.

Publisher Copyright:
© 2016 American Chemical Society.

Keywords

SERS
magnetic nanofocusing
magnetic trapping
magnetoplasmonics
template stripping

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10.1021/acsami.5b12157

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title = "Template-Stripped Multifunctional Wedge and Pyramid Arrays for Magnetic Nanofocusing and Optical Sensing",

abstract = "We present large-scale reproducible fabrication of multifunctional ultrasharp metallic structures on planar substrates with capabilities including magnetic field nanofocusing and plasmonic sensing. Objects with sharp tips such as wedges and pyramids made with noble metals have been extensively used for enhancing local electric fields via the lightning-rod effect or plasmonic nanofocusing. However, analogous nanofocusing of magnetic fields using sharp tips made with magnetic materials has not been widely realized. Reproducible fabrication of sharp tips with magnetic as well as noble metal layers on planar substrates can enable straightforward application of their material and shape-derived functionalities. We use a template-stripping method to produce plasmonic-shell-coated nickel wedge and pyramid arrays at the wafer-scale with tip radius of curvature close to 10 nm. We further explore the magnetic nanofocusing capabilities of these ultrasharp substrates, deriving analytical formulas and comparing the results with computer simulations. These structures exhibit nanoscale spatial control over the trapping of magnetic microbeads and nanoparticles in solution. Additionally, enhanced optical sensing of analytes by these plasmonic-shell-coated substrates is demonstrated using surface-enhanced Raman spectroscopy. These methods can guide the design and fabrication of novel devices with applications including nanoparticle manipulation, biosensing, and magnetoplasmonics.",

keywords = "SERS, magnetic nanofocusing, magnetic trapping, magnetoplasmonics, template stripping",

author = "Shailabh Kumar and Johnson, {Timothy W.} and Wood, {Christopher K.} and Tao Qu and Wittenberg, {Nathan J.} and Otto, {Lauren M.} and Jonah Shaver and Long, {Nicholas J.} and Victora, {Randall H.} and Edel, {Joshua B.} and Oh, {Sang Hyun}",

note = "Funding Information: This work was supported by grants from the National Science Foundation (NSF CAREER Award for S.K., N.J.W., L.M.O., S.H.O.; NSF Graduate Research Fellowship for L.M.O.), Seagate Technology through the Center for Micromagnetics and Information Technologies (MINT) at the University of Minnesota (J.S., T.Q., S.H.O., R.H.V.), EPSRC (J.B.E., C.K.W., and N.J.L.), ERC (J.B.E.), and the MnDrive Initiative (N.J.W. and S.H.O). S.H.O. also acknowledges the NSF program: Research Opportunities in Europe for NSF CAREER awardees (DBI 1338654), which supported this collaboration between the University of Minnesota and Imperial College London. S.K. was supported by the Doctoral Dissertation Fellowship from the University of Minnesota. Device fabrication was performed at the Minnesota Nano Center at the University of Minnesota, which receives support from the NSF through the National Nanotechnology Coordinated Infrastructure. Computational modeling using COMSOL Multiphysics was performed through the University of Minnesota Supercomputing Institute. Publisher Copyright: {\textcopyright} 2016 American Chemical Society.",

year = "2016",

month = apr,

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doi = "10.1021/acsami.5b12157",

language = "English (US)",

volume = "8",

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T1 - Template-Stripped Multifunctional Wedge and Pyramid Arrays for Magnetic Nanofocusing and Optical Sensing

AU - Kumar, Shailabh

AU - Johnson, Timothy W.

AU - Wood, Christopher K.

AU - Qu, Tao

AU - Wittenberg, Nathan J.

AU - Otto, Lauren M.

AU - Shaver, Jonah

AU - Long, Nicholas J.

AU - Victora, Randall H.

AU - Edel, Joshua B.

AU - Oh, Sang Hyun

N1 - Funding Information: This work was supported by grants from the National Science Foundation (NSF CAREER Award for S.K., N.J.W., L.M.O., S.H.O.; NSF Graduate Research Fellowship for L.M.O.), Seagate Technology through the Center for Micromagnetics and Information Technologies (MINT) at the University of Minnesota (J.S., T.Q., S.H.O., R.H.V.), EPSRC (J.B.E., C.K.W., and N.J.L.), ERC (J.B.E.), and the MnDrive Initiative (N.J.W. and S.H.O). S.H.O. also acknowledges the NSF program: Research Opportunities in Europe for NSF CAREER awardees (DBI 1338654), which supported this collaboration between the University of Minnesota and Imperial College London. S.K. was supported by the Doctoral Dissertation Fellowship from the University of Minnesota. Device fabrication was performed at the Minnesota Nano Center at the University of Minnesota, which receives support from the NSF through the National Nanotechnology Coordinated Infrastructure. Computational modeling using COMSOL Multiphysics was performed through the University of Minnesota Supercomputing Institute. Publisher Copyright: © 2016 American Chemical Society.

PY - 2016/4/27

Y1 - 2016/4/27

N2 - We present large-scale reproducible fabrication of multifunctional ultrasharp metallic structures on planar substrates with capabilities including magnetic field nanofocusing and plasmonic sensing. Objects with sharp tips such as wedges and pyramids made with noble metals have been extensively used for enhancing local electric fields via the lightning-rod effect or plasmonic nanofocusing. However, analogous nanofocusing of magnetic fields using sharp tips made with magnetic materials has not been widely realized. Reproducible fabrication of sharp tips with magnetic as well as noble metal layers on planar substrates can enable straightforward application of their material and shape-derived functionalities. We use a template-stripping method to produce plasmonic-shell-coated nickel wedge and pyramid arrays at the wafer-scale with tip radius of curvature close to 10 nm. We further explore the magnetic nanofocusing capabilities of these ultrasharp substrates, deriving analytical formulas and comparing the results with computer simulations. These structures exhibit nanoscale spatial control over the trapping of magnetic microbeads and nanoparticles in solution. Additionally, enhanced optical sensing of analytes by these plasmonic-shell-coated substrates is demonstrated using surface-enhanced Raman spectroscopy. These methods can guide the design and fabrication of novel devices with applications including nanoparticle manipulation, biosensing, and magnetoplasmonics.

AB - We present large-scale reproducible fabrication of multifunctional ultrasharp metallic structures on planar substrates with capabilities including magnetic field nanofocusing and plasmonic sensing. Objects with sharp tips such as wedges and pyramids made with noble metals have been extensively used for enhancing local electric fields via the lightning-rod effect or plasmonic nanofocusing. However, analogous nanofocusing of magnetic fields using sharp tips made with magnetic materials has not been widely realized. Reproducible fabrication of sharp tips with magnetic as well as noble metal layers on planar substrates can enable straightforward application of their material and shape-derived functionalities. We use a template-stripping method to produce plasmonic-shell-coated nickel wedge and pyramid arrays at the wafer-scale with tip radius of curvature close to 10 nm. We further explore the magnetic nanofocusing capabilities of these ultrasharp substrates, deriving analytical formulas and comparing the results with computer simulations. These structures exhibit nanoscale spatial control over the trapping of magnetic microbeads and nanoparticles in solution. Additionally, enhanced optical sensing of analytes by these plasmonic-shell-coated substrates is demonstrated using surface-enhanced Raman spectroscopy. These methods can guide the design and fabrication of novel devices with applications including nanoparticle manipulation, biosensing, and magnetoplasmonics.

KW - SERS

KW - magnetic nanofocusing

KW - magnetic trapping

KW - magnetoplasmonics

KW - template stripping

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JO - ACS applied materials & interfaces

JF - ACS applied materials & interfaces

SN - 1944-8244

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ER -

Template-Stripped Multifunctional Wedge and Pyramid Arrays for Magnetic Nanofocusing and Optical Sensing

Abstract

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