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Abhyankar N, Agrawal A, Shrestha P, Maier R, McMichael RD, Campbell J, Szalai V. Scalable microresonators for room-temperature detection of electron spin resonance from dilute, sub-nanoliter volume solids. SCIENCE ADVANCES 2020; 6:6/44/eabb0620. [PMID: 33115735 PMCID: PMC7608791 DOI: 10.1126/sciadv.abb0620] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 09/14/2020] [Indexed: 06/11/2023]
Abstract
We report a microresonator platform that allows room temperature detection of electron spins in volumes on the order of 100 pl, and demonstrate its utility to study low levels of dopants in perovskite oxides. We exploit the toroidal moment in a planar anapole, using a single unit of an anapole metamaterial architecture to produce a microwave resonance exhibiting a spatially confined magnetic field hotspot and simultaneously high quality-factor (Q-factor). To demonstrate the broad implementability of this design and its scalability to higher frequencies, we deploy the microresonators in a commercial electron paramagnetic resonance (EPR) spectrometer operating at 10 GHz and a NIST-built EPR spectrometer operating at 35 GHz. We report continuous-wave (CW) EPR spectra for various samples, including a dilute Mn2+-doped perovskite oxide, CaTiO3, and a transition metal complex, CuCl22H2O. The anapole microresonator presented here is expected to enable multifrequency EPR characterization of dopants and defects in perovskite oxide microcrystals and other volume-limited materials of technological importance.
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Affiliation(s)
- Nandita Abhyankar
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD 20742, USA.
- National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Amit Agrawal
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD 20742, USA
- National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Pragya Shrestha
- National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Theiss Research, La Jolla, CA 92037, USA
| | - Russell Maier
- National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Robert D McMichael
- National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Jason Campbell
- National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Veronika Szalai
- National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
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Sidabras JW, Duan J, Winkler M, Happe T, Hussein R, Zouni A, Suter D, Schnegg A, Lubitz W, Reijerse EJ. Extending electron paramagnetic resonance to nanoliter volume protein single crystals using a self-resonant microhelix. SCIENCE ADVANCES 2019; 5:eaay1394. [PMID: 31620561 PMCID: PMC6777973 DOI: 10.1126/sciadv.aay1394] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 09/06/2019] [Indexed: 05/26/2023]
Abstract
Electron paramagnetic resonance (EPR) spectroscopy on protein single crystals is the ultimate method for determining the electronic structure of paramagnetic intermediates at the active site of an enzyme and relating the magnetic tensor to a molecular structure. However, crystals of dimensions typical for protein crystallography (0.05 to 0.3mm) provide insufficient signal intensity. In this work, we present a microwave self-resonant microhelix for nanoliter samples that can be implemented in a commercial X-band (9.5 GHz) EPR spectrometer. The self-resonant microhelix provides a measured signal-to-noise improvement up to a factor of 28 with respect to commercial EPR resonators. This work opens up the possibility to use advanced EPR techniques for studying protein single crystals of dimensions typical for x-ray crystallography. The technique is demonstrated by EPR experiments on single crystal [FeFe]-hydrogenase (Clostridium pasteurianum; CpI) with dimensions of 0.3 mm by 0.1 mm by 0.1 mm, yielding a proposed g-tensor orientation of the Hox state.
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Affiliation(s)
- Jason W. Sidabras
- Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Jifu Duan
- AG Photobiotechnologie, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum, Germany
| | - Martin Winkler
- AG Photobiotechnologie, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum, Germany
| | - Thomas Happe
- AG Photobiotechnologie, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum, Germany
| | - Rana Hussein
- Institut für Biologie, Humboldt-Universität zu Berlin, Philippstraße 13, 10115 Berlin, Germany
| | - Athina Zouni
- Institut für Biologie, Humboldt-Universität zu Berlin, Philippstraße 13, 10115 Berlin, Germany
| | - Dieter Suter
- Experimentelle Physik, Technische Universität Dortmund, Emil-Figge-Straße 50, 44221 Dortmund, Germany
| | - Alexander Schnegg
- Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Wolfgang Lubitz
- Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Edward J. Reijerse
- Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
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Kiss SZ, Rostas AM, Heidinger L, Spengler N, Meissner MV, MacKinnon N, Schleicher E, Weber S, Korvink JG. A microwave resonator integrated on a polymer microfluidic chip. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 270:169-175. [PMID: 27497077 DOI: 10.1016/j.jmr.2016.07.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 07/16/2016] [Accepted: 07/18/2016] [Indexed: 06/06/2023]
Abstract
We describe a novel stacked split-ring type microwave (MW) resonator that is integrated into a 10mm by 10mm sized microfluidic chip. A straightforward and scalable batch fabrication process renders the chip suitable for single-use applications. The resonator volume can be conveniently loaded with liquid sample via microfluidic channels patterned into the mid layer of the chip. The proposed MW resonator offers an alternative solution for compact in-field measurements, such as low-field magnetic resonance (MR) experiments requiring convenient sample exchange. A microstrip line was used to inductively couple MWs into the resonator. We characterised the proposed resonator topology by electromagnetic (EM) field simulations, a field perturbation method, as well as by return loss measurements. Electron paramagnetic resonance (EPR) spectra at X-band frequencies were recorded, revealing an electron-spin sensitivity of 3.7·10(11)spins·Hz(-1/2)G(-1) for a single EPR transition. Preliminary time-resolved EPR experiments on light-induced triplet states in pentacene were performed to estimate the MW conversion efficiency of the resonator.
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Affiliation(s)
- S Z Kiss
- Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
| | - A M Rostas
- Institute of Physical Chemistry (IPC), University of Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - L Heidinger
- Institute of Physical Chemistry (IPC), University of Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - N Spengler
- Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - M V Meissner
- Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - N MacKinnon
- Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - E Schleicher
- Institute of Physical Chemistry (IPC), University of Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - S Weber
- Institute of Physical Chemistry (IPC), University of Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - J G Korvink
- Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
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