A miniaturized dual-mode continuous-wave and pulsed pumping ODNP platform

Journal of Magnetic Resonance Open, vol. 21, pp. 100174

Abstract

In this paper, we present the design and experimental validation of a miniaturized Overhauser dynamic nuclear polarization (ODNP) platform for both continuous-wave (CW) and pulsed DNP enhancement experiments at a B 0 field strength of 0.25 T. The platform is centered around chip-integrated nuclear magnetic resonance (NMR) and microwave (MW) electronics and further incorporates a custom-designed laser-engraved ODNP probe, providing phase-coherent radio frequency (RF) excitation, low-noise amplification and acquisition of NMR signals, MW frequency synthesis, MW signal modulation, and MW power amplification. An experimental validation using TEMPOL solutions with different concentrations demonstrates the functionality and good performance of the presented ODNP platform. A maximum enhancement of − 92 with CW pumping was achieved using a 500 nL 10 mM non-degassed TEMPOL solution in water, representing the largest enhancement achieved to date in a chip-based ODNP platform. We also include a preliminary comparison between CW pumping and pulsed pumping using TEMPOL solutions with different electron relaxation times (apparent T 1 e ∗ and T 2e ). Our study indicates that, for a power-limited miniaturized ODNP platform, pulsed pumping can surpass CW pumping in power efficiency for a given average power when the solution possesses a sufficiently long electron spin-lattice relaxation time. • Miniaturized ODNP platform based on chip-integrated NMR and MW electronics. • CW and pulsed DNP experiments are demonstrated with the ODNP platform. • A signal enhancement of − 92 is achieved using CW pumping at room temperature. • Pulsed pumping can be more energy-efficient than CW pumping in power-limited systems.

Authors 8

1. Qing Yang

   University of Stuttgart

   Affiliation as printed

   Institute of Smart Sensors, University of Stuttgart, Pfaffenwaldring 47, Stuttgart, 70569, Germany

2. Hadi Lotfi

   University of Stuttgart

   Affiliation as printed

   Institute of Smart Sensors, University of Stuttgart, Pfaffenwaldring 47, Stuttgart, 70569, Germany

3. Michal Kern corresponding

   University of Stuttgart

   Affiliation as printed

   Institute of Smart Sensors, University of Stuttgart, Pfaffenwaldring 47, Stuttgart, 70569, Germany

4. Frederik Dreyer

   University of Stuttgart

   Affiliation as printed

   Institute of Smart Sensors, University of Stuttgart, Pfaffenwaldring 47, Stuttgart, 70569, Germany

5. Mazin Jouda

   Karlsruhe Institute of Technology

   Affiliation as printed

   Institute of Microstructure Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen, 76344, Germany

6. Jan Gerrit Korvink

   Karlsruhe Institute of Technology

   Affiliation as printed

   Institute of Microstructure Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen, 76344, Germany

7. Bernhard Blümich Aachen Institut für Technische und Makromolekulare Chemie

   RWTH Aachen University

   Affiliation as printed

   Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 2, Aachen, 52074, Germany

8. Jens Anders

   University of Stuttgart · Institut für Mikroelektronik Stuttgart

   Affiliation as printed

   Institute for Microelectronics Stuttgart (IMS CHIPS), Stuttgart, Germany

   Institute of Smart Sensors, University of Stuttgart, Pfaffenwaldring 47, Stuttgart, 70569, Germany