Single-chip electron spin resonance detectors operating at 50 GHz, 92 GHz, and 146 GHz

Matheoud, Alessandro Valentino; Gualco, Gabriele; Jeong, Minki; Živković, Ivica; Brugger, Jürgen; Rønnow, Henrik M.; Anders, Jens; Boero, Giovanni

doi:10.1016/j.jmr.2017.03.013

Cited by 30 publications

(21 citation statements)

References 57 publications

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“…The single-chip CMOS detector offer a robust planar working surface, but its very small detection volume (about 0.2 nL) sets challenging fabrication constraints for the microfluidic design, which must hold the sample in close proximity of the microcoil without introducing significant static magnetic field inhomogeneities. To overcome these challenges, we fabricated microfluidic structures using a high spatial resolution 3D printer (Photonic Professionals GT, Nanoscribe GmbH, Germany), based on a two-photon polymerization process [ 62 , 63 ] and having a resolution better than 1 μm 3 . With this approach, we managed to fabricate microchannels capable to confine the samples under investigation at distances of about 10 μm from the microcoil surface.…”

Section: Introductionmentioning

confidence: 99%

3D printed microchannels for sub-nL NMR spectroscopy

et al. 2018

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Nuclear magnetic resonance (NMR) experiments on subnanoliter (sub-nL) volumes are hindered by the limited sensitivity of the detector and the difficulties in positioning and holding such small samples in proximity of the detector. In this work, we report on NMR experiments on liquid and biological entities immersed in liquids having volumes down to 100 pL. These measurements are enabled by the fabrication of high spatial resolution 3D printed microfluidic structures, specifically conceived to guide and confine sub-nL samples in the sub-nL most sensitive volume of a single-chip integrated NMR probe. The microfluidic structures are fabricated using a two-photon polymerization 3D printing technique having a resolution better than 1 μm3. The high spatial resolution 3D printing approach adopted here allows to rapidly fabricate complex microfluidic structures tailored to position, hold, and feed biological samples, with a design that maximizes the NMR signals amplitude and minimizes the static magnetic field inhomogeneities. The layer separating the sample from the microcoil, crucial to exploit the volume of maximum sensitivity of the detector, has a thickness of 10 μm. To demonstrate the potential of this approach, we report NMR experiments on sub-nL intact biological entities in liquid media, specifically ova of the tardigrade Richtersius coronifer and sections of Caenorhabditis elegans nematodes. We show a sensitivity of 2.5x1013 spins/Hz1/2 on 1H nuclei at 7 T, sufficient to detect 6 pmol of 1H nuclei of endogenous compounds in active volumes down to 100 pL and in a measurement time of 3 hours. Spectral resolutions of 0.01 ppm in liquid samples and of 0.1 ppm in the investigated biological entities are also demonstrated. The obtained results may indicate a route for NMR studies at the single unit level of important biological entities having sub-nL volumes, such as living microscopic organisms and eggs of several mammalians, humans included.

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Section: Introductionmentioning

confidence: 99%

3D printed microchannels for sub-nL NMR spectroscopy

et al. 2018

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“…Reducing the power consumption in LC oscillators is of crucial importance, e.g., for their application as single-chip electron spin resonance (ESR) spectroscopy detectors at low temperatures [36]- [41]. Exploring the behavior of microwave LC oscillators in cryogenic conditions is also interesting for studies of the phase noise of thermal and nonthermal origins [17], [42].…”

Section: Introductionmentioning

confidence: 99%

A Low-Power Microwave HEMT $LC$ Oscillator Operating Down to 1.4 K

Matheoud

Solmaz

Boero

2019

IEEE Trans. Microwave Theory Techn.

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High-electron-mobility transistors (HEMTs) based on 2-D electron gases (2DEGs) in III-V heterostructures have superior mobility compared with the transistors of silicon-based complementary metal-oxide-semiconductor technologies. The large mobility makes them attractive not only for low-noise and high-power microwave applications but also for low-power applications down to deep cryogenic temperatures. Here, we report on the design and characterization of a low-power HEMT LC Colpitts oscillator operating at 11 GHz whose minimum power consumption is 90 µW at 300 K and 4 µW at 1.4 K. The fully integrated oscillator is based on a single HEMT transistor having a gate length of 70 nm and realized using a 2DEG in In 0.7 Ga 0.3 As. The power consumption of the realized oscillator is the lowest reported in the literature so far for an LC oscillator operating in the same frequency range. In order to investigate the behavior of the oscillator, we also performed a detailed characterization of a stand-alone HEMT transistor from 1.4 to 300 K with a static magnetic field from 0 to 8 T. From the extracted values of the transistor parameters, we estimate and compare the minimum power necessary to start-up oscillations for two different Colpitts topologies.

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“…been reported in the literature, cf. Anders et al (2012a); Twig et al (2013); Gualco et al (2014); Matheoud et al (2017Matheoud et al ( , 2018.…”

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confidence: 99%

“…By using integrated LC tank oscillators, this approach removes the need for expensive external B 1 -field sources and also benefits from the great scaling potential of modern nanometer-scaled CMOS technologies and their very high maximum operating frequencies. Exploiting these advantages and utilizing a 45 µm detection coil inside an LC tank oscillator operating around 146 GHz, the design presented by Matheoud et al (2017) achieves a spin sensitivity of about 2 × 10 7 spins/(G • √ Hz). The oscillator-based detection concept was then extended to the use of voltage-controlled oscillators (VCOs) by Handwerker et al (2016), which allows for a great simplification of the experimental setup, thereby, for the first time, enabling the design of battery-operated, portable ESR spectrometers.…”

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confidence: 99%

“…While in reports by Anders et al (2012a), Matheoud et al (2017) and Yalcin and Boero (2008) only the frequency-sensitive detection option of an LC tank oscillator was discussed, a second mode of detection is available in oscillator-based ESR detectors because the oscillation amplitude is also affected by the ESR signal. This concept was first published by Matheoud et al (2018) using an LC Colpitts oscillator.…”

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On the modeling of amplitude-sensitive ESR detection using VCO-based ESR-on-a-chip detectors

Chu¹,

Schlecker²,

Kern³

et al. 2021

Preprint

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Abstract. In this paper, we present an in-depth analysis of a voltage-controlled oscillator (VCO) based sensing method for electron spin resonance (ESR) spectroscopy, which greatly simplifies the experimental setup compared to conventional detection schemes. In contrast to our previous oscillator-based ESR detectors, where the ESR signal was encoded in the oscillation frequency, in the amplitude-sensitive method, the ESR signal is sensed as a change of the oscillation amplitude of the VCO. Therefore, using a VCO architecture with a built-in amplitude demodulation scheme, the experimental setup reduces to a single permanent magnet in combination with a few inexpensive electronic components. We present a theoretical analysis of the achievable limit of detection, which uses a perturbation theory based VCO-modeling for the signal and applies a stochastic averaging approach to obtain a closed-form expression for the noise floor. Additionally, the paper also introduces a numerical model suitable for simulating oscillator-based ESR experiments in a conventional circuit simulator environment. This model can, e.g., be used to optimize sensor performance early on in the design phase. Finally, all presented models are verified against measured results from a prototype VCO operating at 14 GHz inside a 0.5 T magnetic field.

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Single-chip electron spin resonance detectors operating at 50 GHz, 92 GHz, and 146 GHz

Cited by 30 publications

References 57 publications

3D printed microchannels for sub-nL NMR spectroscopy

3D printed microchannels for sub-nL NMR spectroscopy

A Low-Power Microwave HEMT $LC$ Oscillator Operating Down to 1.4 K

On the modeling of amplitude-sensitive ESR detection using VCO-based ESR-on-a-chip detectors

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