Planar microcoil-based microfluidic NMR probes

Massin, C.; Vincent, Franck; Homsy, Alexandra; Ehrmann, Klaus; Boero, Giovanni; Besse, P.‐A.; Daridon, Antoine; Verpoorte, Elisabeth; Rooij, N. F. de; Popović, R.S.

doi:10.1016/s1090-7807(03)00151-4

Cited by 195 publications

(204 citation statements)

References 31 publications

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“…However, all of these techniques require low temperatures. For liquid samples at room temperature, pioneering work on fabrication of solenoids around capillary tubes (16,24) and microfabrication techniques to create planar coils on semiconductor substrates (1,25) demonstrates that miniaturization of probes is possible and substantially reduces sample quantity while retaining signal sensitivity (15). Solenoidal microcoils detect nanomole quantities with high sensitivity but have not been successfully fabricated below Ϸ300 m inner diameter (26), whereas planar coils on semiconductor substrates are scalable but show lower signal sensitivity due to inhomogeneous broadening and path loss.…”

Section: N Uclear Magnetic Resonance (Nmr) Is a Powerful Analyticalmentioning

confidence: 99%

Ultra-small-sample molecular structure detection using microslot waveguide nuclear spin resonance

Maguire

Chuang

Zhang

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

102

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We here report on the design of a planar microslot waveguide NMR probe with an induction element that can be fabricated at scales from centimeters to nanometers to allow analysis of biomolecules at nano-or picomole quantities, reducing the required amount of materials by several orders of magnitude. This device demonstrates the highest signal-to-noise ratio for a planar detector to date, measured by using the anomeric proton signal from a 15.6-nmol sample of sucrose. This probe had a linewidth of 1.1 Hz for pure water without susceptibility matching. Analysis of 1.57 nmol of ribonuclease-A shows high sensitivity in one-and twodimensional NMR spectra. Along with reducing required sample volumes, this integrated geometry can be packed in parallel arrays and combined with microfluidic systems. Further development of this device may have broad implications not only for advancing our understanding of many intractable protein structures and their folding, molecular interactions, and dynamic behaviors, but also for high-sensitivity diagnosis of a number of protein conformational diseases.inductive microslot ͉ miniature probe fabrication ͉ nanomole RNAase-A structural detection ͉ nuclear magnetic resonance scaling ͉ ultra-sensitivity N uclear magnetic resonance (NMR) is a powerful analytical tool not only for determining complex biomolecular structures (1-4) but also for monitoring molecular dynamics (5-7). Despite its versatility, NMR protein and large-molecule structural analyses currently require large quantities of protein material at high concentration and purity (8-10), and timeconsuming data gathering (11-13). Furthermore, it has been difficult to obtain adequate amounts of proteins with high molecular weight, many protein complexes, and especially membrane proteins for structural analysis because they can form insoluble aggregates (14). We here report design and fabrication of a microdevice that can analyze nanomole quantities of proteins (15)(16)(17)(18)(19), and that can be integrated in microfabricated systems.The ultimate sensitivity limit is a single spin. Single-electron spins have been detected by using mechanical oscillations (20) and by single nuclear spins using optical methods (21,22). For a volume on the order of Ϸ10 8 spins, a report of a novel semiconductor detection mechanism shows electronic detection of small quantities of spin 3/2 nuclei at the nanoscale (23). However, all of these techniques require low temperatures. For liquid samples at room temperature, pioneering work on fabrication of solenoids around capillary tubes (16, 24) and microfabrication techniques to create planar coils on semiconductor substrates (1, 25) demonstrates that miniaturization of probes is possible and substantially reduces sample quantity while retaining signal sensitivity (15). Solenoidal microcoils detect nanomole quantities with high sensitivity but have not been successfully fabricated below Ϸ300 m inner diameter (26), whereas planar coils on semiconductor substrates are scalable but show lower signal sensitivit...

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Section: N Uclear Magnetic Resonance (Nmr) Is a Powerful Analyticalmentioning

confidence: 99%

Ultra-small-sample molecular structure detection using microslot waveguide nuclear spin resonance

Maguire

Chuang

Zhang

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

102

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“…6 the Joule heating threshold has been determined for all three side channel lengths (20,50 and 100 m) with a 1 M buffer, as well as for all three buffer concentrations (0.25, 0.5 and 1 M) in a pump with 20 m long side channels. Table 4 summarizes those values.…”

Section: Joule Heating and Power Consumptionmentioning

confidence: 99%

“…The MHD body force (180.5 Pa) and flow velocity (2.8 mm s −1 ) performance in NMR environment of our pump surpassed any previously published MHD pumps of similar dimensions (see Table 1). The final aim of this work is to integrate our MHD pump together with planar coils in a microfluidic system for NMR analysis [20]. The high performance of the pump at relatively low flow rates is seen as an asset for NMR and MRI applications.…”

Section: Measurements In Nmr Superconductive Magnetmentioning

confidence: 99%

Magnetohydrodynamic pumping in nuclear magnetic resonance environments

Homsy

Linder

Lucklum

et al. 2007

Sensors and Actuators B: Chemical

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We present a DC magnetohydrodynamic (MHD) pump as component of a nuclear magnetic resonance (NMR) microfluidic chip. This is the first time that MHD pumping in an NMR environment was observed and demonstrated. This chip generates a maximum flow rate of 1.5 L min −1 (2.8 mm s −1 in the microchannel) for an applied voltage of 19 V with only 38 mW of power consumption in a 7 T superconductive magnet. We developed a simple method of flow rate measurement inside the bulky NMR magnet by monitoring the displacement of a liquid-liquid interface of two immiscible liquids in an off-chip capillary. We compared and validated this flow measurement technique with another established technique for microfluidics based on the displacement of microbeads. This allowed us to characterize and compare the flow rate generated by the micropump on top of a permanent magnet (B 1 = 0.33 T) with the superconductive magnet (B 0 = 7.05 T). We observed a 21-fold increase in flow rate corresponding to the ratio of the magnetic field intensities (B 0 /B 1 = 21) in accordance with the theoretical flow dependence on the magnetic field intensity. The final aim is to integrate MHD pumps together with planar coils in a microfluidic system for NMR analysis. The high performance of MHD pumps at relatively low flow rates is seen as an asset for NMR and MRI applications.

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“…Massin et al [25] micromachined planar copper electroplated microcoils on a Pyrex-glass substrate with etched microchannels. They recorded the 1 H spectrum at 300 MHz for 160 mg sucrose in 470 nL D 2 O (a 1 M solution) using two different designs of the microcoil.…”

Section: Nmr Detectionmentioning

confidence: 99%

Unconventional detection methods for microfluidic devices

2006

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The direction of modern analytical techniques is to push for lower detection limits, improved selectivity and sensitivity, faster analysis time, higher throughput, and more inexpensive analysis systems with ever-decreasing sample volumes. These very ambitious goals are exacerbated by the need to reduce the overall size of the device and the instrumentation -the quest for functional micrototal analysis systems epitomizes this. Microfluidic devices fabricated in glass, and more recently, in a variety of polymers, brings us a step closer to being able to achieve these stringent goals and to realize the economical fabrication of sophisticated instrumentation. However, this places a significant burden on the detection systems associated with microchip-based analysis systems. There is a need for a universal detector that can efficiently detect sample analytes in real time and with minimal sample manipulation steps, such as lengthy labeling protocols. This review highlights the advances in uncommon or less frequently used detection methods associated with microfluidic devices. As a result, the three most common methods -LIF, electrochemical, and mass spectrometric techniques -are omitted in order to focus on the more esoteric detection methods reported in the literature over the last 2 years.

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Planar microcoil-based microfluidic NMR probes

Cited by 195 publications

References 31 publications

Ultra-small-sample molecular structure detection using microslot waveguide nuclear spin resonance

Ultra-small-sample molecular structure detection using microslot waveguide nuclear spin resonance

Magnetohydrodynamic pumping in nuclear magnetic resonance environments

Unconventional detection methods for microfluidic devices

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