On-chip three dimensional microcoils for MRI at the microscale

Badilita, Vlad; Kratt, K.; Baxan, Nicoleta; Mohmmadzadeh, M.; Burger, Tobias; Weber, Hans; Elverfeldt, Dominik von; Hennig, Jürgen; Korvink, Jan G.; Wallrabe, Ulrike

doi:10.1039/c000840k

Cited by 64 publications

(54 citation statements)

References 14 publications

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“…Micro-fabricated receiver structures can be directly integrated into lab-on-achip devices, and systems with limits of detection as low as 0.025 nmol · s 1/2 have been reported in the literature 5 . Different detector geometries and microfabrication strategies for microfluidic NMR have been described, including solenoids [6][7][8] , planar spirals [9][10][11][12] , and microslots/micro striplines [13][14][15][16] . While these approaches yield similar sensitivity for a given probe volume, resolution in the vicinity of 0.01 ppm has only been achieved with very simple, linear fluidic geometries (capillar- ies).…”

Section: Introductionmentioning

confidence: 99%

“…While these approaches yield similar sensitivity for a given probe volume, resolution in the vicinity of 0.01 ppm has only been achieved with very simple, linear fluidic geometries (capillar- ies). By contrast, sample shapes with smaller aspect ratios such as circular or cylindrical chambers, while useful for microimaging, have not yielded satisfactory resolution for liquidstate proton NMR spectroscopy 8,9 .…”

Section: Introductionmentioning

confidence: 99%

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Structural shimming for high-resolution nuclear magnetic resonance spectroscopy in lab-on-a-chip devices

2014

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High-resolution proton NMR spectroscopy is well-established as a tool for metabolomic analysis of biological fluids at the macro scale. Its full potential has, however, not been realised yet in the context of microfluidic devices. While microfabricated NMR detectors offer substantial gains in sensitivity, limited spectral resolution resulting from mismatches in the magnetic susceptibility of the sample fluid and the chip material remains a major hurdle. In this contribution, we show that susceptibility broadening can be compensated even in the presence of substantial mismatch by including suitably shaped compensation structures into the chip design. An efficient algorithm for the calculation of field maps from arbitrary chip layouts based on Gaussian quadrature is used to optimise the shape of the compensation structure to ensure a flat field distribution inside the sample area. Previously, the complexity of microfluidic NMR systems has been restricted to simple capillaries to avoid susceptibility broadening. The structural shimming approach introduced here can be adapted to virtually any shape of sample chamber and surrounding fluidic network, thereby greatly expanding the design space and enabling true lab-on-a-chip systems suitable for high-resolution NMR detection.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structural shimming for high-resolution nuclear magnetic resonance spectroscopy in lab-on-a-chip devices

2014

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“…Based on the above capability, [77,78] presented the first application of wirebonded coils for on-chip magnetic resonance imaging of tiny samples (Table 2-b). Wire-bonded coils were produced, tuned and matched to 400 MHz for use in a 9.4 T Nuclear Magnetic Resonance (NMR) magnet as 1H proton spin resonance detectors.…”

Section: Unconventional Applications Of Wire Bonding Using Standard Wmentioning

confidence: 99%

Unconventional applications of wire bonding create opportunities for microsystem integration

Fischer

Korvink

Roxhed

et al. 2013

J. Micromech. Microeng.

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, G. et al. (2013) "Unconventional applications of wire bonding create opportunities for microsystem integration" Journal of Micromechanics and Microengineering, 23(8) Abstract. Automatic wire bonding is a highly mature, cost-efficient and broadly available back-end process, intended to create electrical interconnections in semiconductor chip packaging. Modern production wire bonding tools can bond wires with speeds of up to 30 bonds per second with placement accuracies of better than 2 µm, and the ability to form each wire individually into a desired shape. These features render wire bonding a versatile tool also for integrating wires in applications other than electrical interconnections. Wire bonding has been adapted and used to implement a variety of innovative microstructures. This paper reviews unconventional uses and applications of wire bonding that have been reported in the literature. The used wire bonding techniques and materials are discussed, and the implemented applications are presented. They include the realization and integration of coils, transformers, inductors, antennas, electrodes, through silicon vias (TSVs), plugs, liquid and vacuum seals, plastic fibers, shape memory alloy (SMA) actuators, energy harvesters, and sensors.

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“…One such example is a solenoidal coil with inner radius of 37.5 µm and 5 turns for which an SNR of 13.6 was reported. 4 Another miniaturized 3D solenoidlike coil, fabricated by Badilita et al, 5 exhibited a high Q factor of 46 at 400 MHz and has been successfully used for MRI.…”

Section: Appendixmentioning

confidence: 99%

Design of planar microcoil-based NMR probe ensuring high SNR

2017

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A microNMR probe for ex vivo applications may consist of at least one microcoil, which can be used as the oscillating magnetic field (MF) generator as well as receiver coil, and a sample holder, with a volume in the range of nanoliters to micro-liters, placed near the microcoil. The Signal-to-Noise ratio (SNR) of such a probe is, however, dependent not only on its design but also on the measurement setup, and the measured sample. This paper introduces a performance factor P independent of both the proton spin density in the sample and the external DC magnetic field, and which can thus assess the performance of the probe alone. First, two of the components of the P factor (inhomogeneity factor K and filling factor η) are defined and an approach to calculate their values for different probe variants from electromagnetic simulations is devised. A criterion based on dominant component of the magnetic field is then formulated to help designers optimize the sample volume which also affects the performance of the probe, in order to obtain the best SNR for a given planar microcoil. Finally, the P factor values are compared between different planar microcoils with different number of turns and conductor aspect ratios, and planar microcoils are also compared with conventional solenoids. These comparisons highlight which microcoil geometry-sample volume combination will ensure a high SNR under any external setup.

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On-chip three dimensional microcoils for MRI at the microscale

Cited by 64 publications

References 14 publications

Structural shimming for high-resolution nuclear magnetic resonance spectroscopy in lab-on-a-chip devices

Structural shimming for high-resolution nuclear magnetic resonance spectroscopy in lab-on-a-chip devices

Unconventional applications of wire bonding create opportunities for microsystem integration

Design of planar microcoil-based NMR probe ensuring high SNR

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