The next step in miniaturization of analytical devices involves the use of MEMS and Lab-on-a-Chip applications, where many biological or chemical reactions are carried out on the device in real time. Since detection mechanisms occur almost immediately after the reactions, inefficient mixing of reagents could cause a decrease in sensing capability, especially on micro- and nano-scaled devices. Thus a microfluidic mixer has become a crucial component in these applications. Here we propose a new design of a passive microfluidic mixer that utilizes the theories of chaotic advection to enhance mixing. The micro-channels for the mixer have dimensions with width ranging from 10µm to 40µm, depth 40µm, and a total length of 280µm. First the designs are simulated using CFD-ACE+ for computational analysis. After the device geometry has been decided, the actual devices are fabricated using traditional UV photolithography on silicon and bonded with pyrex glass by anodic bonding. To test the actual device mixing efficiency, we used a fluorescent dye rhodamine B solution to mix with DI water and put the devices under fluorescent microscope observations for real-time analysis. Images of fluorescent light intensities are taken at different flow rates during the analysis and are later used to study the experimental results calculated using a published mixing efficiency formula for comparison.

The next step in miniaturization of analytical devices involves the use of MEMS and Lab-on-a-Chip applications, where many biological or chemical reactions are carried out on the device in real time. Since detection mechanisms occur almost immediately after the reactions, inefficient mixing of reagents could cause a decrease in sensing capability, especially on micro- and nano-scaled devices. Thus a microfluidic mixer has become a crucial component in these applications. Here we propose a new design of a passive microfluidic mixer that utilizes the theories of chaotic advection to enhance mixing. The micro-channels for the mixer have dimensions with width ranging from 10µm to 40µm, depth 40µm, and a total length of 280µm. First the designs are simulated using CFD-ACE+ for computational analysis. After the device geometry has been decided, the actual devices are fabricated using traditional UV photolithography on silicon and bonded with pyrex glass by anodic bonding. To test the actual device mixing efficiency, we used a fluorescent dye rhodamine B solution to mix with DI water and put the devices under fluorescent microscope observations for real-time analysis. Images of fluorescent light intensities are taken at different flow rates during the analysis and are later used to study the experimental results calculated using a published mixing efficiency formula for comparison.

No description available.

M.Ing. (Electrical and Electronic Engineering) / An extensive literature survey revealed that the existing process design methods for specifying the power requirements of industrial mixers depended either upon an assumption of laminar flow conditions, or on a comparison with a Newtonian liquid, or both. In fact, real industrial mixers often experience flow regimes ranging from laminar near the walls of the vessel to fully turbulent in the impeller zone. Moreover, industrial liquids are rarely Newtonian in character. A method of torque monitoring is proposed for fully describing the power requirements of an industrial mixer to suspend a mineral slurry. This method, by incorporating a critical dimension, the impeller diameter, is suitable for scale-up. It was tested in a uranium leaching application with good results. The "comparative viscosity" of the slurry can also be derived. This parameter is suitable for process control purposes.

Thesis (M.S.)--Rutgers University, 2009. / "Graduate Program in Food Science." Includes bibliographical references (p. 88-90).

Thesis (Ph. D.)--Rutgers University, 2008. / "Graduate Program in Food Science." Includes bibliographical references (p. 147-152).

Thesis (MScEng) -- Stellenbosch University, 2002. / Some digitised pages may appear illegible due to the condition of the original hard copy. / ENGLISH ABSTRACT: Harmonic mixers are capable of extended frequency operation by mixing with a harmonic of the LO (local oscillator) signal, eliminating the need for a high frequency, high power LO. Their output spectra also have certain characteristics that make them ideal for a variety of applications. The operation of the harmonic mixer is investigated, and the mixer is analyzed using an extension of the classic mixer theory. The synthesis of harmonic mixers is also investigated, and a design procedure is proposed for the design and realization of a variety of harmonic mixers. This design procedure is evaluated with the design and realization of two harmonic mixers, one in X-band and the other in S-band. Measurements suggest that the procedure is successful for the specific applications. / AFRIKAANSE OPSOMMING: Harmoniese mengers kan by hoer frekwensies gebruik word as gewone mengers deurdat hulle gebruik maak van ‘n harmoniek van die LO. ‘n Hoe-frekwensie, hoe-drywing LO word dus nie benodig nie. Die mengers se uittreespektra het ook ‘n aantal karakteristieke wat hulle goeie kandidate maak vir ‘n verskeidenheid van toepassings. Die werking van die harmoniese menger word ondersoek deur uit te brei op die klassieke menger-teorie. Die ontwerp van die harmoniese menger word vervolgens ondersoek, waama ‘n ontwerpsprosedure voorgestel word vir die ontwerp van ‘n verskeidenheid van harmoniese mengers. Hierdie prosedure word getoets met die ontwerp en realisering van twee harmoniese mengers, een in X-band en die ander in S-band. Vanuit die metings is dit duidelik dat die ontwerpsprosedure geslaagd is vir die spesifieke geval.

No description available.

In this thesis, three low-noise active mixing circuits are presented in CMOS technology. Mixers can be found at the front-end of almost every communication systems. However, despite many advantages the active mixers have, one drawback is their poor noise performance. One mixer that has been widely used in integrated circuit is the Gilbert cell. This thesis demonstrated that by merging the low-noise amplifier (LNA) with the Gilbert cell, a low-noise active mixer can be realized. This kind of mixer relaxes the front-end design, allows higher circuit integration, and reduces power consumption. The first circuit is a narrowband low-noise mixer that operates at 5.4 GHz in 0.18 um CMOS. An inductive degenerated LNA is used as the transconductor. Together with a current bleeding circuit, a gain of 13.1 dB and a low 7.8 dB single-sideband noise figure are achieved. The circuit was fabricated and measured. Simulation and measurement results are compared and discussed. The second circuit is a broadband low-noise mixer that operates between 1 and 5.5 GHz in 0.13 um CMOS. The noise-cancelling technique is used to design the transconductors. This technique does not require the use of inductors while able to achieve a sub 3 dB noise figure and input matching over a large bandwidth. To further extend the mixer bandwidth, the series inductive peaking was used. Measured and simulated results showed great agreement. It has a high gain of 17.5 dB, a bandwidth of 4.5 GHz, and a low average double-sideband noise figure of 3.9 dB. This mixer has the best broadband noise performance ever reported in CMOS. Finally, a double-balanced low-noise self-oscillating mixer (SOM) in 0.13 um CMOS is presented. This is a current-reuse, highly integrated circuit that combines an LNA, mixer, and oscillator seamlessly into a single component. The oscillator generates the required LO while serving as the mixer load simultaneously. Measured and simulated results showed excellent agreement. A low double-sideband noise figure of 4.4 dB and a gain of 11.6 dB were measured. This type of SOM and loading structure are the first ever reported. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2009-08-23 12:41:20.445

This report is a product of Bachelor Degree Project at Mechanical Engineering department inLinnaeus University, Växjö, Sweden. The project is about a design improvement of industrialcompact mixers.This project is accomplished with Xylem, one of the main suppliers of compact mixers in theindustry, located at Emmaboda, Sweden. The company has a problem with the existing designof the two part, oil housing and entrance cover, in 4610/20 compact mixers. The 4610/20compact mixers has suffered from quality problems which affect the production and the endcustomer because of the existing design of these part. The aim of this study is to improve thequality of the product by redesigning of oil housing and entrance cover. In addition to theredesigning of these parts, another important purpose of the project is to produce these partsfrom different material than existing one.The computer aided design programs are widely used, Solid Works, during the project. Forselection of a new material a wide literature research has been accomplished.