A5101956235- Microfluidic and Capillary Electrophoresis Applications
- Advanced MEMS and NEMS Technologies
- Innovative Microfluidic and Catalytic Techniques Innovation
- 3D IC and TSV technologies
- Microfluidic and Bio-sensing Technologies
- Radio Frequency Integrated Circuit Design
- Nanofabrication and Lithography Techniques
- Semiconductor materials and devices
- Electrowetting and Microfluidic Technologies
- Advanced Surface Polishing Techniques
- Advanced Sensor Technologies Research
- Advancements in Photolithography Techniques
- Advanced Power Amplifier Design
- Nanowire Synthesis and Applications
- Plasma Diagnostics and Applications
- Catalytic Processes in Materials Science
- Mechanical and Optical Resonators
- Advanced Fiber Optic Sensors
- Photonic and Optical Devices
- Electronic Packaging and Soldering Technologies
- Additive Manufacturing and 3D Printing Technologies
- Analog and Mixed-Signal Circuit Design
- Gas Dynamics and Kinetic Theory
- Advanced Sensor and Energy Harvesting Materials
- Advancements in PLL and VCO Technologies
Leibniz Institute of Surface Engineering
2017-2024
University of Stuttgart
2009-2020
Massachusetts Institute of Technology
2005-2019
Saarland University
2018
Technische Universität Berlin
2007-2015
University of Maryland, College Park
2000-2006
University of California, Los Angeles
2006
Stanford University
2006
University of California, Santa Barbara
2006
University of Illinois Urbana-Champaign
2006
An analytic and experimental investigation into gaseous flow with slight rarefaction through long microchannels is undertaken. A two-dimensional (2-D) analysis of the Navier-Stokes equations a first-order slip-velocity boundary condition demonstrates that both compressibility rarefied effects are present in microchannels. By undertaking perturbation expansion /spl epsiv/, height-to-length ratio channel, using ideal gas equation state, it shown zeroth-order solution for streamwise mass...
A microchemical device has been built in silicon and glass by using microfabrication methods including deep-reactive-ion etch technology, photolithography, multiple wafer bonding. The system consists of a microfluidic distribution manifold, microchannel array, 25-μm microfilter for immobilizing solid particulate material within the reactor chip carrying out different heterogeneous chemistries. Multiple reagent streams (specifically, gas liquid streams) are mixed on-chip, fluid brought into...
Wafer-to-wafer bonding processes for microstructure fabrication are categorized and described. These have an impact in packaging structure design. Processes into direct bonds, anodic bonds with intermediate layers. Representative devices using wafer-to-wafer presented. methods characterization of a range discussed. Opportunities continued development outlined.
We present an integrated microfluidic system that achieves efficient mixing between two miscible liquid streams by introducing a gas phase, forming segmented gas-liquid (slug) flow, and completely separating the mixed in planar capillary separator. The recirculation motion associated with flow enhances advection straight microchannels without requiring additional fabrication steps. Instantaneous velocity fields are quantified microscopic particle image velocimetry (muPIV). Velocities...
We demonstrate the design, fabrication, and operation of microfluidic chemical reactors for synthesis colloidal silica particles. Two reactor configurations are examined: laminar flow segmented reactors. analyze particle sizes size distributions examine their change with varying linear velocity mean residence time. Laminar affected by axial dispersion at high velocities, thus leading to wide under these conditions. Gas is used create a flow, consisting liquid plugs separated inert gas...
We report the experimentally obtained response surfaces of silicon etching rate, aspect ratio dependent (ARDE), photoresist and anisotropy parameter in a time multiplexed inductively coupled plasma etcher. The data were collected while varying eight variables. relevance electrode power, pressure, gas flow rates is presented has been found to agree with observations reported literature. observed behavior this serves as tool locate optimize operating conditions etch high structures....
We have developed a microfabricated device for use in parallel luminescent single-cell assays that can sort populations upon the basis of dynamic functional responses to stimuli. This is composed regular array noncontact traps. These traps dielectrophoresis stably confine cells and hold them against disrupting fluid flows. Using quantitative modeling, we designed with novel asymmetric extruded-quadrupole geometry. new trap be physically arrayed electrically addressed, enabling our cytometer....
We demonstrate a micro-electroporation device for cell lysis prior to subcellular analysis. Simple circuit models show that electrical method is advantageous because it selective towards plasma membrane while leaving organelle undamaged. In addition, miniaturization of this concept leads negligible heat generation and bubble formation. The designed microdevices were fabricated using combination photolithography, metal-film deposition, electroplating. the electro-lysis human carcinoma cells...
High-precision experimental results are reported showing the tangential momentum accommodation coefficient (TMAC) for several gases in contact with single-crystal silicon to be less than unity. A precise and robust platform is demonstrated measurement of mass flows through micromachined channels due an imposed pressure gradient. Analytic expressions isothermal Maxwellian slip long used determine TMAC at a variety Knudsen numbers. Results from experiments using nitrogen, argon carbon dioxide...
Monodisperse CdSe quantum dots (QDs) with excellent optical properties can be prepared a gas–liquid segmented flow microreactor multiple temperature zones (see picture; red=heated; blue=cooled quench zone). The enhanced mixing and narrow residence time distributions of produce QDs superior to those in single-phase operations. Microfluidic reactors enable number advantages over conventional chemical processes including control heat mass transfer, lower reagent consumption during optimization,...
Abstract Silicon‐based microfabrication of a novel chemical reactor (microreactor) having submillimeter flow channels with integrated heaters, and temperature sensors is described. The potential application this to partial‐oxidation reactions explored by using Pt‐catalyzed NH 3 oxidation as model reaction. Investigation behavior function operating conditions shows that conversion selectivity conventional laboratory reactors can be reproduced demonstrates the feasibility conducting in...
Using silicon microfabrication technology, microchemical devices have been constructed for the purpose of conducting heterogeneously catalyzed multiphase reactions. The motivation behind design, fabrication approach, and experimental characterization are presented two classes devices. first design involves multiple parallel channels with integrated filter structures to incorporate standard catalytic materials. These catalysts in form finely divided porous particles a packed-bed arrangement....
This paper describes a method for fabricating microfluidic devices in photodefinable epoxy (SU-8). technique is compatible with, and complementary to, conventional fabrication techniques. It allows microstructures formed SU-8 to be bonded produce sealed channels. A micromixer fabricated entirely SU-8, using this technique, performing liquid-phase reactions shown suitable visible spectroscopy. also the incorporation of materials that are often difficult integrate. By hybrid incorporate quartz...
This work presents an application of microfabricated reactors and detectors for photochemical reactions. Two fabrication schemes were demonstrated the integration reaction detection modules: coupling individually packaged chips, monolithic two functions. In latter scheme, we have succeeded in bonding quartz wafers to patterned silicon at low temperature using a Teflon-like polymer-CYTOP[trade mark sign]. Using substrates allows with UV light lower wavelengths than Pyrex permit. The pinacol...
A microfabricated floating-element shear-stress sensor for measurements in turbulent boundary-layers is reported. Using surface micromachining of polyimide, a 500- mu m*500- m probe has been fabricated incorporating differential-capacitor readout circuit. model the response described and used design an element to measure shear stresses 1 Pa air. The packaged calibration laminar flow, electrical results obtained match expected response.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML"...
Continuous-flow dielectrophoretic (DEP) particle separation based on size is demonstrated in a microfluidic device. Polystyrene microspheres suspended neutrally buoyant aqueous solution are used as model particles to study DEP induced by an array of slanted, planar, interdigitated electrodes inside soft-lithography microchannel. The E-field gradients from the slanted impart net transverse force component that causes them "ratchet" across channel. Over length device, larger deflected more...
Nucleated red blood cells (NRBCs) have been identified in maternal circulation and potentially provide a resource for the monitoring diagnosis of maternal, fetal, neonatal health disease. Past strategies used to isolate enrich NRBCs are limited complex approaches that result low recovery less than optimal cell purity. Here we report development high-throughput highly efficient microfluidic device isolating rare from blood.NRBCs were isolated peripheral 58 pregnant women using process...
Many microfabricated systems require metallizations that can withstand high temperatures. In particular, a chemical reactor system which we are investigating needs thin metal films for heating and temperature sensing prolonged 1000/spl deg/C exposure. The current microreactor metallization, 100-nm platinum film with 10-nm titanium adhesion layer, degrades at temperatures greater than 700/spl deg/C. This degradation was examined custom-built high-temperature resistance measurement apparatus...
We describe a microchemical reactor built by silicon processing and metal deposition techniques that enables efficient safe direct fluorination of toluene, highly exothermic process difficult to implement conventionally on macroscopic scale. Gas liquid reagents were contacted cocurrently at room temperature in the microfabricated reactor, gas−liquid distribution patterns characterized. A flow regime map, containing slug annular-dry flows, was obtained for velocities relevant reactions...
Here we demonstrate the microfabrication of deep (>25 μm) polymeric microstructures created by replica-molding polydimethylsiloxane (PDMS) from microfabricated Si substrates. The use PDMS structures in microfluidics and biological applications is discussed. We investigated feasibility two methods for molds: plasma etch silicon-on-insulator (SOI) wafers photolithographic patterning a spin-coated photoplastic layer. Although SOI can be patterned at higher resolution, found that inexpensive...
We present a suspended-tube chemical reactor/heat exchanger for high-temperature fuel processing in micro energy conversion systems, primarily hydrogen production portable cell systems. This reactor, designed to thermally isolate reaction zone, consists of four free-standing silicon nitride tubes comprising two independent U-shaped fluidic channels. Portions the are encased enable heat exchange between fluids these A thin-film platinum resistor is embedded localized heating and temperature...
MIT is developing a MEMS-based gas turbine generator. Based on high speed rotating machinery, this 1 cm diameter by 3 mm thick SiC heat engine designed to produce 10-20 W of electric power while consuming 10 grams/hr H/sub 2/. Later versions may up 100 using hydrocarbon fuels. The combustor now operating and an 80 micro-turbine has been fabricated being tested. This can be considered the first new class MEMS device, MEMS, which are engines at densities similar those best large scale devices...