Magnetic forces are now being utilised in an amazing variety of microfluidic applications. Magnetohydrodynamic flow has been applied to the pumping of fluids through microchannels. Magnetic materials such as ferrofluids or magnetically doped PDMS have been used as valves. Magnetic microparticles have been employed for mixing of fluid streams. Magnetic particles have also been used as solid supports for bioreactions in microchannels. Trapping and transport of single cells are being investigated and recently, advances have been made towards the detection of magnetic material on-chip. The aim of this review is to introduce and discuss the various developments within the field of magnetism and microfluidics.

Magnetism and microfluidics

Micro total analysis systems. Recent developments.

Part I: Background and Fundamentals Introduction, Mohamed Gad-el-Hak, University of Notre Dame Scaling of Micromechanical Devices, William Trimmer, Standard MEMS, Inc., and Robert H. Stroud, Aerospace Corporation Mechanical Properties of MEMS Materials, William N. Sharpe, Jr., Johns Hopkins University Flow Physics, Mohamed Gad-el-Hak, University of Notre Dame Integrated Simulation for MEMS: Coupling Flow-Structure-Thermal-Electrical Domains, Robert M. Kirby and George Em Karniadakis, Brown University, and Oleg Mikulchenko and Kartikeya Mayaram, Oregon State University Liquid Flows in Microchannels, Kendra V. Sharp and Ronald J. Adrian, University of Illinois at Urbana-Champaign, Juan G. Santiago and Joshua I. Molho, Stanford University Burnett Simulations of Flows in Microdevices, Ramesh K. Agarwal and Keon-Young Yun, Wichita State University Molecular-Based Microfluidic Simulation Models, Ali Beskok, Texas A&M University Lubrication in MEMS, Kenneth S. Breuer, Brown University Physics of Thin Liquid Films, Alexander Oron, Technion, Israel Bubble/Drop Transport in Microchannels, Hsueh-Chia Chang, University of Notre Dame Fundamentals of Control Theory, Bill Goodwine, University of Notre Dame Model-Based Flow Control for Distributed Architectures, Thomas R. Bewley, University of California, San Diego Soft Computing in Control, Mihir Sen and Bill Goodwine, University of Notre Dame Part II: Design and Fabrication Materials for Microelectromechanical Systems Christian A. Zorman and Mehran Mehregany, Case Western Reserve University MEMS Fabrication, Marc J. Madou, Nanogen, Inc. LIGA and Other Replication Techniques, Marc J. Madou, Nanogen, Inc. X-Ray-Based Fabrication, Todd Christenson, Sandia National Laboratories Electrochemical Fabrication (EFAB), Adam L. Cohen, MEMGen Corporation Fabrication and Characterization of Single-Crystal Silicon Carbide MEMS, Robert S. Okojie, NASA Glenn Research Center Deep Reactive Ion Etching for Bulk Micromachining of Silicon Carbide, Glenn M. Beheim, NASA Glenn Research Center Microfabricated Chemical Sensors for Aerospace Applications, Gary W. Hunter, NASA Glenn Research Center, Chung-Chiun Liu, Case Western Reserve University, and Darby B. Makel, Makel Engineering, Inc. Packaging of Harsh-Environment MEMS Devices, Liang-Yu Chen and Jih-Fen Lei, NASA Glenn Research Center Part III: Applications of MEMS Inertial Sensors, Paul L. Bergstrom, Michigan Technological University, and Gary G. Li, OMM, Inc. Micromachined Pressure Sensors, Jae-Sung Park, Chester Wilson, and Yogesh B. Gianchandani, University of Wisconsin-Madison Sensors and Actuators for Turbulent Flows. Lennart Loefdahl, Chalmers University of Technology, and Mohamed Gad-el-Hak, University of Notre Dame Surface-Micromachined Mechanisms, Andrew D. Oliver and David W. Plummer, Sandia National Laboratories Microrobotics Thorbjoern Ebefors and Goeran Stemme, Royal Institute of Technology, Sweden Microscale Vacuum Pumps, E. Phillip Muntz, University of Southern California, and Stephen E. Vargo, SiWave, Inc. Microdroplet Generators. Fan-Gang Tseng, National Tsing Hua University, Taiwan Micro Heat Pipes and Micro Heat Spreaders, G. P. "Bud" Peterson, Rensselaer Polytechnic Institute Microchannel Heat Sinks, Yitshak Zohar, Hong Kong University of Science and Technology Flow Control, Mohamed Gad-el-Hak, University of Notre Dame) Part IV: The Future Reactive Control for Skin-Friction Reduction, Haecheon Choi, Seoul National University Towards MEMS Autonomous Control of Free-Shear Flows, Ahmed Naguib, Michigan State University Fabrication Technologies for Nanoelectromechanical Systems, Gary H. Bernstein, Holly V. Goodson, and Gregory L. Snider, University of Notre Dame Index

The MEMS Handbook

Rapid and accurate measurement of biomarkers in tissue and fluid samples is a major challenge in medicine. Here we report the development of a new, miniaturized diagnostic magnetic resonance (DMR) system for multiplexed, quantitative and rapid analysis. By using magnetic particles as a proximity sensor to amplify molecular interactions, the handheld DMR system can perform measurements on unprocessed biological samples. We show the capability of the DMR system by using it to detect bacteria with high sensitivity, identify small numbers of cells and analyze them on a molecular level in real time, and measure a series of protein biomarkers in parallel. The DMR technology shows promise as a robust and portable diagnostic device.

/pdf/chip-nmr-biosensor-for-detection-and-molecular-analysis-of-3h7yxudmsx.pdf

Chip–NMR biosensor for detection and molecular analysis of cells

Significant progress has been made recently in demonstrating that silicon photonics is a promising technology for low-cost optical detectors, modulators and light sources1,2,3,4,5,6,7,8,9,10,11,12. It has often been assumed, however, that their performance is inferior to InP-based devices. Although this is true in most cases, one of the exceptions is the area of avalanche photodetectors, where silicon's material properties allow for high gain with less excess noise than InP-based avalanche photodetectors and a theoretical sensitivity improvement of 3 dB or more. Here, we report a monolithically grown germanium/silicon avalanche photodetector with a gain–bandwidth product of 340 GHz, a keff of 0.09 and a sensitivity of −28 dB m at 10 Gb s−1. This is the highest reported gain–bandwidth product for any avalanche photodetector operating at 1,300 nm and a sensitivity that is equivalent to mature, commercially available III–V compound avalanche photodetectors. This work paves the way for the future development of low-cost, CMOS-based germanium/silicon avalanche photodetectors operating at data rates of 40 Gb s−1 or higher. A monolithically grown Ge/Si avalanche photodetectors (APD) with a gain–bandwidth product of 340 GHz, the highest value for any APDs operating at 1,300 nm, and a sensitivity equivalent to commercially available III-V compound APDs is reported. The excellent performance paves the way to achieving low-cost, CMOS-based, Ge/Si APDs operating at data rates of 40 Gb s−1 or higher, where the performance of III-V APDs is severely limited.

https://www.nature.com/articles/nphoton.2008.247.pdf?proof=t

Monolithic germanium/silicon avalanche photodiodes with 340 GHz gain-bandwidth product

In the recent years, a great deal of research has been devoted to dead-space effects in avalanche photodiodes (APD) with submicron multiplication regions. Measurements and theoretical models have shown that the multiplication noise in SAM-APDs and in GaAs and InP p/sub +/in/sup +/ APDs decreases when the thickness of the multiplication layer is reduced. We present excess noise measurements of a Si ultraviolet-selective (UVS) APD with a 100 nm thick multiplication region. We show that these results are in excellent agreement with simulations using the dead-space model. The excess noise of our structure is much smaller than predicted by McIntyre's continuum theory.

Dead-space effect on noise in Si UV-selective avalanche photodiode

SUMMARY We analyze the problem of scaling down an inductive proximity sensor made of superposed multiple-turn flat coils. We linearly scale down all geometrical dimensions. Then the nominal inductance is scaled down proportionally to the scale factor. The coupling factor of the superposed coils remains constant. However for both ferromagnetic and non-ferromagnetic targets, the sensitivity remains constant when the frequency is scaled by the inverse square of the reduction factor. But the parasitic effects in the sensor coil become more important for small device dimensions. Therefore these effects are expected to set the ultimate limit in the miniaturization of the integrated inductive proximity sensors.

Scaling Down An Inductive Proximity Sensor

Figure 2: Implementation ofthe vertical Hall device in microelectronic processes3. applied. This kind of sensor can be produced on a silicon wafer using microelectronic-like technologies. Despite the relatively low sensitivity of silicon devices compared to moresophisticated materials, these components are well suited for mass production at very low cost and their longterm stability and signal-to-noise ratio are excellent2. Vertical and cylindrical Hall devices The Hall effect produces a voltage proportional to the magnetic field Magnetic sensor microsystems

https://journals.sagepub.com/doi/pdf/10.1177/002029400003300902

P.-A. Besse

Papers

Dead-space effect on noise in Si UV-selective avalanche photodiode

Scaling Down An Inductive Proximity Sensor

Realised examples of microsystems and their applications