Microfluidic sub-millisecond mixers for the study of chemical reaction kinetics

Desai, Amish; Bökenkamp, Dirk; Yang, Xing; Tai, Yu-Chong; Marzluff, Elaine M.; Mayo, Stephen L.

doi:10.1109/sensor.1997.613609

Cited by 8 publications

(3 citation statements)

References 11 publications

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“…Mixing is usually evaluated by visualization methods using fluorescent dyes [6], [9], [13], [15], [16], pH indicators [20], [31] and color dyes [19], [32]. In this paper, we use food color dyes (orange and blue colored) for their simplicity and high contrast.…”

Section: Experimental Investigationmentioning

confidence: 99%

A magnetic microstirrer and array for microfluidic mixing

Ryu

Liu

2002

J. Microelectromech. Syst.

384

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We report the development of a micromachined magnetic-bar micromixer for microscale fluid mixing in biological laboratory-on-a-chip applications. The mixer design is inspired by large scale magnetic bar mixers. A rotating magnetic field causes a single magnetic bar or an array of them to rotate rapidly within a fluid environment. A fabrication process of the magnetic bar mixer is developed. Results of fluid mixing in micro channels and chambers are investigated using experimental means and computer-aided fluid simulation.[729]

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Section: Experimental Investigationmentioning

confidence: 99%

A magnetic microstirrer and array for microfluidic mixing

Ryu

Liu

2002

J. Microelectromech. Syst.

384

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“…To date, micromixing devices − operate in low Reynolds number regimes and have mixing times on the order of seconds. We show here that decreasing mixer volume and distances between the mixing chambers combined with high flow velocities enabled us to achieve greatly reduced dead times …”

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confidence: 94%

Microfabricated Silicon Mixers for Submillisecond Quench-Flow Analysis

et al. 1998

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Elucidation of fast chemical reactions such as protein folding requires resolution on a submillisecond time scale. However, most quench-flow and stop-flow techniques only allow chemical processes to be studied after a few milliseconds have elapsed. In order to shorten the minimum observation time for quench-flow experiments, we designed a miniaturized mixer assembly. Two “T” mixers connected by a channel are etched into a 1 cm × 1 cm silicon chip which is interfaced with a commercially available quench-flow instrument. Decreasing the volume of the mixing chambers and the distance between them results in an instrument with greatly reduced dead times. As a test of submillisecond measurements, we studied the basic hydrolysis of phenyl chloroacetate. This reaction proceeds with a second-order rate constant, k = 430 M-1 s-1, and shows pseudo-first-order kinetics at high hydroxide concentrations. The chemical reaction data demonstrate that the silicon device is capable of initiating and quenching chemical reactions in time intervals as short as 110 μs. The performance of these mixers was further confirmed by visualization using acid−base indicators.

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“…The potential to study millisecond rate dynamics with MRI would open up a variety of potential applications. An extremely fast imaging technique could allow MRI of turbulent flow in stenotic vessels (23)(24)(25)(26)(27) and in microfluidic lab-on-a-chip devices where chaotic flow is desired for mixing (28)(29)(30)(31)(32)(33)(34)(35)(36), or to follow millisecond kinetics in chemical reactions (37)(38)(39), or even to enable imaging of destructive events (40)(41)(42)(43)(44)(45) or single-shot imaging of pressure waves in MR elastography (46)(47)(48)(49)(50). Emerging applications, such as hyperpolarized 13 C imaging, which have the potential to enable direct molecular imaging using MRI (51)(52)(53), will require the entire imaging study to be completed in tens rather than hundreds of seconds, placing a premium on dynamic MRI methods.…”

Section: Introductionmentioning

confidence: 99%

Single echo acquisition MRI using RF encoding

Wright

McDougall

2009

NMR in Biomedicine

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Encoding of spatial information in magnetic resonance imaging is conventionally accomplished by using magnetic field gradients. During gradient encoding, the position in k-space is determined by a time-integral of the gradient field, resulting in a limitation in imaging speed due to either gradient power or secondary effects such as peripheral nerve stimulation. Partial encoding of spatial information through the sensitivity patterns of an array of coils, known as parallel imaging, is widely used to accelerate the imaging, and is complementary to gradient encoding. This paper describes the one-dimensional limit of parallel imaging in which all spatial localization in one dimension is performed through encoding by the radiofrequency (RF) coil. Using a one-dimensional array of long and narrow parallel elements to localize the image information in one direction, an entire image is obtained from a single line of k-space, avoiding rapid or repeated manipulation of gradients. The technique, called single echo acquisition (SEA) imaging, is described, along with the need for a phase compensation gradient pulse to counteract the phase variation contained in the RF coil pattern which would otherwise cause signal cancellation in each imaging voxel. Image reconstruction and resolution enhancement methods compatible with the speed of the technique are discussed. MR movies at frame rates of 125 frames per second are demonstrated, illustrating the ability to monitor the evolution of transverse magnetization to steady state during an MR experiment as well as demonstrating the ability to image rapid motion. Because this technique, like all RF encoding approaches, relies on the inherent spatially varying pattern of the coil and is not a time-integral, it should enable new applications for MRI that were previously inaccessible due to speed constraints, and should be of interest as an approach to extending the limits of detection in MR imaging.

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Microfluidic sub-millisecond mixers for the study of chemical reaction kinetics

Cited by 8 publications

References 11 publications

A magnetic microstirrer and array for microfluidic mixing

A magnetic microstirrer and array for microfluidic mixing

Microfabricated Silicon Mixers for Submillisecond Quench-Flow Analysis

Single echo acquisition MRI using RF encoding

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