TABLE II.
Representative examples of various reported microresonator designs and their performance parameters. Figures reproduced with permission from Narkowicz et al., J. Magn. Reson. 175(2), 275–284 (2005). Copyright 2005 Elsevier; from Dayan et al., Rev. Sci. Instrum. 89(12), 124707 (2018) with the permission of AIP Publishing; Bienfait et al., Nat. Nanotechnol. 11(3), 253–257 (2016). Copyright 2016 Springer Nature; Abhyankar et al., Sci. Adv. 6(44), eabb0620 (2020). Copyright 2020 Author(s), licensed under a Creative Commons Attribution 4.0 License; and Sidabras et al., Sci. Adv. 5(10), eaay1394 (2019). Copyright 2019 Author(s), licensed under a Creative Commons Attribution 4.0 License.
| Omega-type loop-gap (2D)73 |
|
Experimental Q-factor (T, ν) | <50 (298 K, 14 GHz) |
| Active volume | 10–100 nl | ||
| Coupling mechanism | Non-variable capacitive | ||
| coupling to coplanar microstrip | |||
| Conversion factor | 5 mT/ | ||
| π/2 pulse length (input power) | 24 ns (17 mW) | ||
| B1 homogeneity | >50% variation within | ||
| active region | |||
| Bow-tie like structures (2D)78 |
|
Experimental Q-factor (T, ν) | <100 (298 K, 35 GHz) |
| Active volume | 0.5–5 nl | ||
| Coupling mechanism | Variable inductive coupling | ||
| Conversion factor | 10 mT/ | ||
| π/2 pulse length (input power) | ⋯ | ||
| B1 homogeneity | >50% variation within | ||
| active region | |||
| Interdigitated resonators (2D)60 |
|
Experimental Q-factor (T, ν) | 3 × 105 (12 mK, 7 GHz) |
| Active volume | 0.02 nl | ||
| Coupling mechanism | Non-variable capacitive | ||
| coupling to input and | |||
| output antennas | |||
| Conversion factor | ⋯ | ||
| π/2 pulse length (input power) | ⋯ | ||
| B1 homogeneity | ⋯ | ||
| Planar inverse anapole (2D)29 |
|
Experimental Q-factor (T, ν) | 200–300 (298 K, 10 or 35 GHz) |
| Active volume | 0.1 nl | ||
| Coupling mechanism | Variable inductive | ||
| coupling to microstrip | |||
| Conversion factor | 10 mT/ | ||
| π/2 pulse length (input power) | ⋯ | ||
| B1 homogeneity | >50% variation within | ||
| active region | |||
| Self-resonant helix (3D)30 |
|
Experimental Q-factor (T, ν) | 220 (298 K, 10 GHz) |
| Active volume | 1 nl | ||
| Coupling mechanism | Variable inductive | ||
| coupling to loop | |||
| Conversion factor | 10 mT/ | ||
| π/2 pulse length (input power) | 20 ns (20 mW) | ||
| B1 homogeneity | <10% variation within | ||
| active volume |