| 1. |
- Enoksson, Peter, 1957, et al.
(författare)
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A Coriolis mass flow sensor structure in silicon
- 1996
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Ingår i: IEEE International Workshop on Micro Electromechanical Systems (1996 MEMS), Feb. 11-15, San Diego, USA.
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Konferensbidrag (refereegranskat)
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| 2. |
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| 3. |
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| 4. |
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| 5. |
- Enoksson, Peter, 1957, et al.
(författare)
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Microfluid Device Research at KTH
- 1996
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Ingår i: Micro Structure Workshop 1996 (MSW’96), March 26-27, Uppsala, Sweden..
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Konferensbidrag (refereegranskat)
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| 6. |
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| 7. |
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| 8. |
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| 9. |
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| 10. |
- Jaouen, Frédéric, et al.
(författare)
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Adhesive copper films for an air-breathing polymer electrolyte fuel cell
- 2005
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 144:1, s. 113-121
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Tidskriftsartikel (refereegranskat)abstract
- A design for an air-breathing and passive polymer electrolyte fuel cell is presented. Such a type of fuel cell is in general promising for portable electronics. In the present design, the anode current collector is made of a thin copper foil. The foil is provided with an adhesive and conductive coating, which firstly tightens the hydrogen compartment without mask or clamping pressure, and secondly secures a good electronic contact between the anode backing and the current collector. The cathode comprises a backing, a gold-plated stainless steel mesh and a current collector cut out from a printed circuit board. Three geometries for the cathode current collector were evaluated. Single cells with an active area of 2 cm(2) yielded a peak power of 250-300 MW cm(-2) with air and pure H-2 in a complete passive mode except for the controlled flow of H-2. The cells' response was investigated in steady state and transient modes.
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| 11. |
- Olsson, Anders, et al.
(författare)
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A valve-less planar pump in silicon
- 1995
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Ingår i: The 8th International Conference on Solid-State Sensors (TRANSDUCERS'95), Stockholm, Sweden, June 25-29. ; , s. 291-294
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Konferensbidrag (refereegranskat)
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| 12. |
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| 13. |
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| 14. |
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| 15. |
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| 16. |
- Olsson, Anders, et al.
(författare)
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Numerical and experimental studies of flat-walled diffuser elements for valve-less micropumps
- 2000
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Ingår i: Sensors and Actuators A-Physical. - 0924-4247 .- 1873-3069. ; 84:02-jan, s. 165-175
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Tidskriftsartikel (refereegranskat)abstract
- An investigation of flat-walled diffuser elements for valve-less micropumps is presented. The diffuser element is a small angle flow channel with a rounded inlet and a preferably sharp outlet. The diverging-wall direction is the positive flow direction. The flow-directing capability under steady flow conditions was determined experimentally for several different diffuser elements. The flow-pressure characteristic was studied in detail for one of them. The result is compared with previously published results on pump performance. Numerical simulations were done using the Computational Fluid Dynamics program ANSYS/Flotran. The simulations show the flow-directing capability of the diffuser elements and predict the flow-pressure characteristics well for Reynolds numbers below 300-400. For higher Reynolds numbers, the simulations show the flow-directing capability, but there is a larger discrepancy between simulations and measurements. Simulations were also done for a nozzle element, a wide-angle flow channel with sharp inlet and outlets used in the micropump with dynamic passive-valves. A nozzle element has the converging-wall direction as positive flow direction. The simulations show differences in the flow patterns for diffuser elements and nozzle elements that explain the opposite positive flow directions. The diffuser element has an ordered flow and takes advantage of the pressure recovery in the diverging-wall direction. The nozzle element has gross flow separation in the diverging-wall direction and there is a vena-contracta effect instead of pressure recovery. The effective cross-sectional area is smaller in the diverging-wall direction than in the converging-wall direction.
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| 17. |
- Stemme, Göran, 1958-, et al.
(författare)
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Förträngningspump av membranpumptyp
- 1993
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Patent (populärvet., debatt m.m.)abstract
- A displacement pump with a pump housing containing a pump chamber of varying volume, the limiting walls of which includes a moveable portion or diaphragm, the movement and/or deformation of which varies the pump chamber volume. The pump chamber has a fluid inlet on the suction side of the pump and a fluid outlet on the pressure side. Both the fluid inlet and the fluid outlet, or possibly only one of them, includes a flow controlling element having one diffuser and one diffuser inlet which, for the same flow, has a larger pressure drop in one flow direction (the nozzle direction) than in the opposite flow direction (the diffuser direction). A drive element is coupled to the diaphragm, whereby the diaphragm can be caused to oscillate, so that the fluid volume in the pump chamber is caused to pulsate and thereby produce a net flow of fluid through the pump.
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| 18. |
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| 19. |
- Stemme, Göran, 1958-, et al.
(författare)
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Trycksensor innefattande en tryckkänslig flat kapsel
- 1989
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Patent (populärvet., debatt m.m.)abstract
- A pressure sensor comprises a pressure-sensitive, flat capsule (1) adapted to be actuated by a pressure which is to be measured, and to be excited to oscillate in mechanical resonance with a resonance frequency dependent on said pressure, as well as to undergo a deformation caused by said pressure, for producing a change in rigidity of the entire capsule (1) and, consequently, an alteration of the resonance frequency thereof. The pressure sensor is characterised in that the capsule (1) is fixed (at 3) with respect to, and adapted to execute said resonance oscillation about, two intersecting unforced nodal lines (10, 11) of the capsule. When the capsule executes its resonance oscillation, it oscillates substantially perpendicular to a geometrical plane common to both nodal lines (10, 11).
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| 20. |
- Svedin, Niklas, et al.
(författare)
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A static turbine flow meter with a micromachined silicon torque sensor
- 2001
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Ingår i: MEMS 2001. - 0780359984 ; , s. 208-211
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Konferensbidrag (refereegranskat)abstract
- A new class of flow sensors is introduced where a static turbine converts the volume flow into a torque. In contrast to conventional turbine meters, the wheel does not rotate and consequently it is not sensitive to bearing friction and wear that a rotating wheel experiences. The sensor performance has been evaluated for different blade lengths and blade angles and a model is given to predict the influence of these parameters. Optimization of the wheel can be done in terms of maximizing the sensitivity/pressure-loss ratio. The most efficient wheel in this analysis has a blade length of 2.7 mm and a blade angle of 30° giving a sensitivity of 4.0 μV/V/(1/min) when measured using a new silicon torque sensor design.
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| 21. |
- Svedin, Niklas, et al.
(författare)
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A static turbine flow meter with a micromachined silicon torque sensor
- 2003
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Ingår i: Journal of microelectromechanical systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1057-7157 .- 1941-0158. ; 12:6, s. 937-946
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Tidskriftsartikel (refereegranskat)abstract
- A new class of flow sensors is introduced where a static turbine converts the volume flow into a torque. The structure consists of a turbine fixed to a torque sensor, which in turn is connected to the pipe wall giving a perfectly symmetric, bidirectional flowmeter. In contrast to conventional turbine flowmeters, the wheel does not rotate and consequently it is insensitive to bearing friction and wear that conventional, rotating turbines experience. Furthermore, the flow passing the wheel is distributed over the circumference of the wheel and levels out nonuniform flow profiles leading to profile independent volumetric flow measurement. The torque-sensing element is a 300-mum-thick silicon cantilever, 2 mm wide and 16 mm long. The stiffness of the torque sensor, and thereby the sensitivity, is mainly determined by lateral dimensions of specially designed stiffness reduction parts defined by photolithography, thus giving good control of the sensitivity. Two polysilicon strain gauges are placed on each side of the cantilever, measuring the bending moment from the turbine wheel. The torque sensor has been evaluated for different geometries and together with the turbine to evaluate the flow sensing performance. A turbine with a blade length of 2.7 mm and a blade angle of 30degrees has a sensitivity of 4.0 muV/V/(1/min)(2) when measured using the silicon torque sensor. The output signal shows good symmetry between different flow directions.
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| 22. |
- Wuttge, Dirk M., et al.
(författare)
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CXCL16/SR-PSOX is an interferon-gamma-regulated chemokine and scavenger receptor expressed in atherosclerotic lesions
- 2004
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Ingår i: Arteriosclerosis, Thrombosis and Vascular Biology. - : American Heart Association. - 1079-5642 .- 1524-4636. ; 24:4, s. 750-755
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Atherosclerosis is an inflammatory disease. Several chemokines are important for monocyte/macrophage and T-cell recruitment to the lesion. CXCL16 is a recently discovered chemokine that is expressed in soluble and transmembrane forms, ligates CXCR6 chemokine receptor, and guides migration of activated Th1 and Tc1 cells. It is identical to scavenger receptor SR-PSOX, which mediates uptake of oxidized low-density lipoprotein. We investigated whether CXCL16 expression is controlled by interferon-gamma (IFN-gamma)-cytokine abundant in atherosclerotic lesions. METHODS AND RESULTS: CXCL16 and CXCR6 expression was identified by polymerase chain reaction and histochemistry in atherosclerotic lesions from humans and apolipoprotein-E-deficient mice. In vitro IFN-gamma induced CXCL16 in human monocytic THP-1 cells and primary human monocytes, which led to increased uptake of oxidized low-density lipoprotein in THP-1 cells, which could be blocked by peptide antibodies against CXCL16. In vivo IFN-gamma induced CXCL16 expression in murine atherosclerotic lesions. CONCLUSIONS: We demonstrate a novel role of IFN-gamma in foam cell formation through upregulation of CXCL16/SR-PSOX. CXCR6 expression in the plaque confirms the presence of cells able to respond to CXCL16. Therefore, this chemokine/scavenger receptor could serve as a molecular link between lipid metabolism and immune activity in the atherosclerotic lesion.
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| 23. |
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| 24. |
- Andersson, Helene, et al.
(författare)
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A valve-less diffuser micropump for microfluidic analytical systems
- 2001
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Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 72:3, s. 259-265
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Tidskriftsartikel (refereegranskat)abstract
- The suitability of valve-less micropumps in biochemistry has been shown. Fluids encountered in various biochemical methods that are problematic for other micropumps have been pumped with good performance. The pump is fabricated as a silicon-glass stack with a new process involving three subsequent deep reactive ion etching steps. Some of the main advantages of the valve-less diffuser pump are the absence of moving parts (excluding the pump diaphragm), the uncomplicated planar design, and high pump performance in terms of pressure head and flow rare. In addition, the micropump is self-priming and insensitive to particles and bubbles present in the pumped media. The results show that the valve-less micropump successfully pumps fluids within the viscosity range of 0.001-0.9 N s/m(2). The micropump is not sensitive to the density, ionic strength, or pH of the pumped media. Effective pumping of solutions containing beads of different sizes was also demonstrated. Living cells were pumped without inducing cell damage and no cell adhesion within the pump chamber was found. No valve-less micropump has previously been reported to pump such a wide variety of fluids.
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| 25. |
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| 26. |
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| 27. |
- Andersson, Helene, et al.
(författare)
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Consecutive microcontact printing - ligands for asymmetric catalysis in silicon channels
- 2001
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Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 79:1, s. 78-84
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Tidskriftsartikel (refereegranskat)abstract
- Consecutive microcontact printing ( mu CP) has been developed to enable multiple functionalization of silicon surfaces, such as the immobilization of chiral ligands. The technique involves two subsequent printing steps using unstructured poly(methylsiloxane) stamps. The pattern is already defined on the substrate, consisting of etched channels. Hence, no precise alignment is needed between the two printing steps. A carboxylic acid group containing reagent was initially printed onto the silicon oxide surface and transformed to an anhydride. hi the second printing step an ester bond was formed with the hydroxy-functionalized ligand. The formed molecular layers were evaluated by contact angle measurements, scanning electron microscopy (SEM) and electron spectroscopy for chemical analysis (ESCA), indicating that the consecutive mu CP was successful. Initially, printing was performed on planar silicon surfaces but to realize a flow-through microfluidic device for high throughput screening a mu CP technique was developed for etched channels. To verify the technique, hydrophobic valves consisting of octadecyltrichlorosilane were formed using mu CP in deep reactive ion etched channels (50 mum wide and 50 mum deep). The printed hydrophobic patches were visualized by SEM and functioned well. Finally, the consecutive mu CP technique was applied to immobilize the ligand in the channels. The channels were then sealed with a low-temperature bonding technique using an adhesive PDMS film, which does not destroy the printed ligand. In this study mu CP is used in a novel manner. It enables a convenient method for performing complex surface modification of etched structures, which is a frequently appearing problem in biochemical microfluidic systems.
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| 28. |
- Andersson, Helene, et al.
(författare)
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Expandable microspheres - surface immobilization techniques
- 2002
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Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 84:2-3, s. 290-295
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a novel component for microfluidics is introduced. Expandable microspheres have been studied for their application in microfluidics. Two methods for selective immobilization of expandable microspheres without the use of mechanical barriers on silicon, including patterning by photolithography and self-assembly based on surface chemistry have been shown. After the immobilization step the microspheres were expanded thermally. The expansion is irreversible and the volume of the microspheres increases more than 60 times. Patterns of microspheres with features as small as 15 pm have successfully been generated by photolithography. By using self-assembly the microspheres can conveniently be immobilized in monolayers. Future applications of the expandable microspheres can be as fluidic components, such as one-shot valves or micropumps, positioning other microcomponents or to enlarge the surface area.
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| 29. |
- Andersson, Helene, et al.
(författare)
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Hydrophobic valves of plasma deposited octafluorocyclobutane in DRIE channels
- 2001
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Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 75:1-2, s. 136-141
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Tidskriftsartikel (refereegranskat)abstract
- The suitability of using octafluorocyclobutane (C4F8) patches as hydrophobic valves in microfluidic biochemical applications has been shown. A technique has been developed to generate lithographically defined C4F8 hydrophobic patches in deep reactive ion-etched silicon channels. Some of the advantages of this process are that no specific cleaning of the substrate is required, C4F8 is deposited on the sidewalls and the bottom of the channels, a standard photoresist mask can be used to define the patches, and that it is a fast and convenient dry chemical process performed by a standard inductively coupled plasma etcher using the Bosch process. Different patch lengths (200-1000 mum) of C4F8 were deposited in 50 mum wide channels to evaluate which size is most suitable for microfluidic biochemical applications. The valve function of the hydrophobic patches was tested for the following liquids: DD water, acetone, propanol, bead solution and a mixture used for pyrosequencing of DNA. Patch lengths of 200 mum of C4F8 successfully stopped each solution for at least 20 consecutive times. The C4F8 film resists water for at least 5 h. The hydrophobic valve also resists very high concentrations (25%) of surfactants (Tween 80). C4F8 shows a much higher resistance towards water and surface active solutions than previous hydrophobic patches. However, 50% Tween 80 was not stopped at all by the hydrophobic patch. An applied pressure of 760 Pa at the inlet was needed for water to over-run the hydrophobic patch.
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| 30. |
- Andersson, Helene, et al.
(författare)
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Micromachined filter-chamber array with passive valves for biochemical assays on beads
- 2001
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Ingår i: Electrophoresis. - 0173-0835 .- 1522-2683. ; 22:2, s. 249-257
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Tidskriftsartikel (refereegranskat)abstract
- The filter-chamber array presented here enables a real-time parallel analysis of three different samples on beads in a volume of 3 nL, on a 1 cm(2) chip. The filter-chamber array is a system containing three filter-chambers, three passive valves at the inlet channels and a common outlet. The design enables parallel sample handling and time-controlled analysis. The device is microfabricated in silicon and sealed with a Pyrex lid to enable real-time analysis. Single nucleotide polymorphism analysis by using pyrose-quencing has successfully been performed in single filter-chamber devices. The passive valves consist of plasma-deposited octafluorocyclobutane and show a much higher resistance towards water and surface-active solutions than previous hydrophobic patches. The device is not sensitive to gas bubbles, clogging is rare and reversible, and the filter-chamber array is reusable. More complex (bio)chemical reactions on beads can be performed in the devices with passive valves than in the devices without valves.
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| 31. |
- Andersson, Helene, et al.
(författare)
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Micromachined flow-through filter-chamber for chemical reactions on beads
- 2000
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Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 67:1-2, s. 203-208
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Tidskriftsartikel (refereegranskat)abstract
- A new flow-through micromachined device for chemical reactions on beads has been designed, manufactured, and characterized. The device has an uncomplicated planar design and microfabrication process. Both nonmagnetic and magnetic beads can be collected in the reaction chamber without the use of external magnets. The sample flow-through volume of liquid or gas is adjustable and unlimited. The device is sealed with Pyrex to allow real time optical detection of the chemical reactions. At a constant pressure of 3 kPa at the inlet the flow rate for water is about 3.5 mu l/min without beads in the filter chamber, for all the designs. The smallest reaction chamber has a volume of 0.5 nl and can collect approximately 50 beads with a diameter of 5.50 mu m. At a constant pressure of 3 kPa at the inlet, the flow rate for water is about 2.0 mu l/min when the reaction chamber is completely packed with beads. Hence, the flow rate decreases with about 40% when the reaction chamber is packed with beads. The flow-through microfluidic device is not sensitive to gas bubbles, and clogging of the filter is rare and reversible. The beads are easy to remove from the reaction chamber making the micromachined flow-through device reusable. A new and simple technique for fluid interconnection is developed.
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| 32. |
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| 33. |
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| 34. |
- Andersson, Helene, et al.
(författare)
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Patterned self-assembled beads in silicon channels
- 2001
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Ingår i: Electrophoresis. - 0173-0835 .- 1522-2683. ; 22:18, s. 3876-3882
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Tidskriftsartikel (refereegranskat)abstract
- A novel technique enabling selective bead trapping in microfluidic devices without the use of physical barriers is presented in this paper. It is a fast, convenient and simple method, involving microcontact printing and self-assembly, that can be applied to silicon, quartz or plastic substrates. In the first step, channels are etched in the substrate. The surface chemistry of the internal walls of the channels is then modified by microcontact printing. The chip is submerged in a bead slurry where beads self-assemble based on surface chemistry and immobilize on the internal walls of the channels. Silicon channels (100 mum wide and 50 mum deep) have been covered with monolayers of streptavidin-, amino- and hydroxy-functionalized microspheres and resulted in good surface coverage of beads on the channel walls. A high-resolution pattern of lines of self-assembled streptavidin beads, as narrow as 5 mum, has also been generated on the bottom of a 500 mum wide and 50 mum deep channel. Flow tests were performed in sealed channels with the different immobilized beads to confirm that the immobilized beads could withstand the forces generated by water flowing in the channels. The presented results indicate that single beads can be precisely positioned within microfluidic devices based on self-assembly which is useful as screening and analysis tools within the field of biochemistry and organic chemistry.
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| 35. |
- Andersson, Helene, et al.
(författare)
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Self-assembled and self-sorted array of chemically active beads for analytical and biochemical screening
- 2002
-
Ingår i: Talanta. - 0039-9140 .- 1873-3573. ; 56:2, s. 301-308
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Tidskriftsartikel (refereegranskat)abstract
- A technique for generating a general screening platform consisting of dots of immobilized beads on silicon has been developed via self-sorting and -assembly of different kinds of beads. The dots are defined by a teflon-like film, which due to its hydrophobic characteristics also prevents cross-contamination of liquid from different dots. To enable functionalization of individual dots with different target molecules simultaneously a new way of microcontact printing has been explored where different target solutions are printed in parallel using one stamp. In order to show that this platform can be designed for both biochemical assays and organic chemistry, streptavidin-, amino- and hydroxy-functionalized beads have been self-sorted and -assembled both on separate and common platforms. The self-sorting and -arrangement are based on surface chemistry only, which has not previously been reported. Beads of different sizes and material have successfully been immobilized in line patterns as narrow as 5 mum. Besides silicon, quartz and polyethylene have also been used as substrates.
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| 36. |
- Antelius, Mikael, et al.
(författare)
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Hermetic integration of liquids in MEMS by room temperature, high-speed plugging of liquid-filled cavities at wafer level
- 2011
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Ingår i: Proceedings IEEE International Conference on Micro Electro Mechanical Systems (MEMS). - : IEEE. ; , s. 356-359
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper reports a novel room temperature hermetic liquid sealing process based on wire bonded "plugs" over the access ports of liquid-filled cavities. The method enables liquids to be integrated already at the fabrication stage. Test vehicles were manufactured and used to investigate the mechanical and hermetic properties of the seals. A helium leak rate of better than 1E-10 mbarL/s was measured on the successfully sealed structures. The bond strength of the "plugs" were similar to standard wire bonds on flat surfaces.
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| 37. |
- Antelius, Mikael, et al.
(författare)
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Hermetic integration of liquids using high-speed stud bump bonding for cavity sealing at the wafer level
- 2012
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Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 22:4, s. 045021-
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports a novel room-temperature hermetic liquid sealing process where the access ports of liquid-filled cavities are sealed with wire-bonded stud bumps. This process enables liquids to be integrated at the fabrication stage. Evaluation cavities were manufactured and used to investigate the mechanical and hermetic properties of the seals. Measurements on the successfully sealed structures show a helium leak rate of better than 10 (10) mbarL s (1), in addition to a zero liquid loss over two months during storage near boiling temperature. The bond strength of the plugs was similar to standard wire bonds on flat surfaces.
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| 38. |
- Antelius, Mikael, et al.
(författare)
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Room-temperature wafer-level vacuum sealing by compression of high-speed wire bonded gold bumps
- 2011
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Ingår i: Proceedings IEEE International Conference on Solid-State Sensors, Actuators, and Microsystems (Transducers). - : IEEE. ; , s. 1360-1363
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper reports experimental results of a novel room temperature vacuum sealing process based on compressing wire bonded gold “bumps”, causing a material flow into the access ports of vacuum-cavities. The leak rate out of manufactured cavities was measured over 5 days and evaluated to less than the detection limit, 6×10-12 mbarL/s, per sealed port. The cavities have been sealed at a vacuum level below 10 mbar. The method enables sealing of vacuum cavities at room temperature using standard commercial tools and processes.
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| 39. |
- Antelius, Mikael, et al.
(författare)
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Small footprint wafer-level vacuum packaging using compressible gold sealing rings
- 2011
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Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 21:8, s. 085011-
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Tidskriftsartikel (refereegranskat)abstract
- A novel low-temperature wafer-level vacuum packaging process is presented. The process uses plastically deformed gold rings as sealing structures in combination with flux-free soldering to provide the bond force for a sealing wafer. This process enables the separation of the sealing and the bonding functions both spatially on the wafer and temporally in different process steps, which results in reduced areas for the sealing rings and prevents outgassing from the solder process in the cavity. This enables space savings and yields improvements. We show the experimental result of the hermetic sealing. The leak rate into the packages is determined, by measuring the package lid deformation over 10 months, to be lower than 3.5 x 10(-13) mbar l s(-1), which is suitable for most MEMS packages. The pressure inside the produced packages is measured to be lower than 10 mbar.
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| 40. |
- Antelius, Mikael, et al.
(författare)
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Wafer-Level Vacuum Sealing by Coining of Wire Bonded Gold Bumps
- 2013
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Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 22:6, s. 1347-1353
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports on the investigation of a novel room-temperature vacuum sealing method based on compressing wire bonded gold bumps which are placed to partially overlap the access ports into the cavity. The bump compression, which is done under vacuum, causes a material flow into the access ports, thereby hermetically sealing a vacuum inside the cavities. The sealed cavity pressure was measured by residual gas analysis to 8x10(-4) mbar two weeks after sealing. The residual gas content was found to be mainly argon, which indicates the source as outgassing inside the cavity and no measurable external leak. The seals are found to be mechanically robust and easily implemented by the use of standard commercial tools and processes.
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| 41. |
- Antelius, Mikael
(författare)
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Wafer-scale Vacuum and Liquid Packaging Concepts for an Optical Thin-film Gas Sensor
- 2013
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis treats the development of packaging and integration methods for the cost-efficient encapsulation and packaging of microelectromechanical (MEMS) devices. The packaging of MEMS devices is often more costly than the device itself, partly because the packaging can be crucial for the performance of the device. For devices which contain liquids or needs to be enclosed in a vacuum, the packaging can account for up to 80% of the total cost of the device.The first part of this thesis presents the integration scheme for an optical dye thin film NO2-gas sensor, designed using cost-efficient implementations of wafer-scale methods. This work includes design and fabrication of photonic subcomponents in addition to the main effort of integration and packaging of the dye-film. A specific proof of concept target was for NO2 monitoring in a car tunnel.The second part of this thesis deals with the wafer-scale packaging methods developed for the sensing device. The developed packaging method, based on low-temperature plastic deformation of gold sealing structures, is further demonstrated as a generic method for other hermetic liquid and vacuum packaging applications. In the developed packaging methods, the mechanically squeezed gold sealing material is both electroplated microstruc- tures and wire bonded stud bumps. The electroplated rings act like a more hermetic version of rubber sealing rings while compressed in conjunction with a cavity forming wafer bonding process. The stud bump sealing processes is on the other hand applied on completed cavities with narrow access ports, to seal either a vacuum or liquid inside the cavities at room temperature. Additionally, the resulting hermeticity of primarily the vacuum sealing methods is thoroughly investigated.Two of the sealing methods presented require permanent mechanical fixation in order to complete the packaging process. Two solutions to this problem are presented in this thesis. First, a more traditional wafer bonding method using tin-soldering is demonstrated. Second, a novel full-wafer epoxy underfill-process using a microfluidic distribution network is demonstrated using a room temperature process.
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| 42. |
- Asiatici, Mikhail, et al.
(författare)
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Capacitive inertial sensing at high temperatures of up to 400 degrees C
- 2016
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Ingår i: Sensors and Actuators A-Physical. - : Elsevier. - 0924-4247 .- 1873-3069. ; 238, s. 361-368
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Tidskriftsartikel (refereegranskat)abstract
- High-temperature-resistant inertial sensors are increasingly requested in a variety of fields such as aerospace, automotive and energy. Capacitive detection is especially suitable for sensing at high temperatures due to its low intrinsic temperature dependence. In this paper, we present high-temperature measurements utilizing a capacitive accelerometer, thereby proving the feasibility of capacitive detection at temperatures of up to 400 degrees C. We describe the observed characteristics as the temperature is increased and propose an explanation of the physical mechanisms causing the temperature dependence of the sensor, which mainly involve the temperature dependence of the Young's modulus and of the viscosity and the pressure of the gas inside the sensor cavity. Therefore a static electromechanical model and a dynamic model that takes into account squeeze film damping were developed.
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| 43. |
- Asiatici, Mikhail, et al.
(författare)
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Through Silicon Vias With Invar Metal Conductor for High-Temperature Applications
- 2017
-
Ingår i: Journal of microelectromechanical systems. - : IEEE Press. - 1057-7157 .- 1941-0158. ; 26:1, s. 158-168
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Tidskriftsartikel (refereegranskat)abstract
- Through silicon vias (TSVs) are key enablers of 3-D integration technologies which, by vertically stacking andinterconnecting multiple chips, achieve higher performances,lower power, and a smaller footprint. Copper is the mostcommonly used conductor to fill TSVs; however, copper hasa high thermal expansion mismatch in relation to the siliconsubstrate. This mismatch results in a large accumulation ofthermomechanical stress when TSVs are exposed to high temperaturesand/or temperature cycles, potentially resulting in devicefailure. In this paper, we demonstrate 300 μm long, 7:1 aspectratio TSVs with Invar as a conductive material. The entireTSV structure can withstand at least 100 thermal cycles from −50 °C to 190 °C and at least 1 h at 365 °C, limited bythe experimental setup. This is possible thanks to matchingcoefficients of thermal expansion of the Invar via conductor andof silicon substrate. This results in thermomechanical stressesthat are one order of magnitude smaller compared to copperTSV structures with identical geometries, according to finiteelement modeling. Our TSV structures are thus a promisingapproach enabling 2.5-D and 3-D integration platforms for hightemperatureand harsh-environment applications.
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| 44. |
- Baghchehsaraei, Zargham, et al.
(författare)
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MEMS 30μm-thick W-band waveguide switch
- 2012
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Ingår i: European Microwave Week 2012. - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 1055-1058, s. 675-678, s. 1055-1058
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Konferensbidrag (refereegranskat)abstract
- This paper presents for the first time a novel concept of a MEMS waveguide switch based on a reconfigurable surface, whose working principle is to short-circuit or to allow for free propagation of the electrical field lines of the TE10 mode of a WR-12 rectangular waveguide. This transmissive surface is only 30μm thick and consists of up to 1260 reconfiguring cantilevers in the waveguide cross-section, which are moved simultaneously by integrated MEMS comb-drive actuators. For the first fabrication run, the yield of these reconfigurable elements on the chips was 80-86%, which still was good enough for resulting in a measured insertion loss in the open state of better than 1dB and an isolation of better than 20dB for the best designs, very wideband from 62 to 75GHz. For 100% fabrication yield, HFSS simulations predict that an insertion loss in the open state of better than 0.1dB and an isolation of better than 30dB in the closed state are possible for designs with 800 and more contact points for this novel waveguide switch concept.
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| 45. |
- Baghchehsaraei, Zargham, et al.
(författare)
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MEMS reconfigurable millimeter-wave surface for V-band rectangular-waveguide switch
- 2013
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Ingår i: International Journal of Microwave and Wireless Technologies. - 1759-0787. ; 5:3, s. 341-349
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents for the first time a novel concept of a microelectromechanical systems (MEMS) waveguide switch based on a reconfigurable surface, whose working principle is to block the wave propagation by short-circuiting the electrical field lines of the TE10 mode of a WR-12 rectangular waveguide. The reconfigurable surface is only 30 mu m thick and consists of up to 1260 micro-machined cantilevers and 660 contact points in the waveguide cross-section, which are moved simultaneously by integrated MEMS comb-drive actuators. Measurements of fabricated prototypes show that the devices are blocking wave propagation in the OFF-state with over 30 dB isolation for all designs, and allow for transmission of less than 0.65 dB insertion loss for the best design in the ON-state for 60-70 GHz. Furthermore, the paper investigates the integration of such microchips into WR-12 waveguides, which is facilitated by tailor-made waveguide flanges and compliant, conductive-polymer interposer sheets. It is demonstrated by reference measurements where the measured insertion loss of the switches is mainly attributed to the chip-to-waveguide assembly. For the first prototypes of this novel MEMS microwave device concept, the comb-drive actuators did not function properly due to poor fabrication yield. Therefore, for measuring the OFF-state, the devices were fixated mechanically.
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| 46. |
- Baghchehsaraei, Zargham, et al.
(författare)
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Millimeter-Wave SPST Waveguide Switch Based on Reconfigurable MEMS Surface
- 2013
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Ingår i: 2013 IEEE MTT-S International Microwave Symposium Digest (IMS). - : IEEE. - 9781467361767 ; , s. 6697774-
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Konferensbidrag (refereegranskat)abstract
- This paper presents a concept of a waveguide single-pole single-throw (SPST) switch based on a MEMSreconfigurable surface. A set of vertical columns, split into two groups of movable and fixed sections which can be actuated laterally by integrated MEMS comb-drive actuators, allows for the transition between the transmissive and the blocking state. In the totally-blocking state, the vertical columns inhibit the wave propagation by short-circuiting the electrical field lines of the predominant TE10 mode. The paper reports on the integration method for fabricated chips into a WR-12 waveguide by using tailor-made flanges. The RF measurement of fabricated chips show that devices have better than 30 dB isolation in the OFF state and better than 0.65 dB insertion loss in the ON state for 60-70 GHz, which is mainly attributed to the integration into the waveguide and the measurement assembly setup. The actuation voltage is 44 V, and life-time measurements were carried out for 14 hours after which 4.3 million cycles were achieved without any indication on degradation.
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| 47. |
- Balslev, Soren, et al.
(författare)
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Microfluidic dye laser with compact, low-cost liquid dye dispenser
- 2005
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Ingår i: Micro Total Analysis Systems 2004. - 0854048960 ; , s. 375-377
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Konferensbidrag (refereegranskat)abstract
- We present a compact system consisting of a miniaturized fluid dispenser, delivering liquid laser dye to a micro-chip dye laser. This demonstrates the elimination of bulk fluid pumps for a microfluidic system by using a miniaturized, electrically and chemically inert dispenser, capable of delivering very low flow for extended periods of time.
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| 48. |
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| 49. |
- Bleiker, Simon J., et al.
(författare)
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Adhesive wafer bonding with ultra-thin intermediate polymer layers
- 2017
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Ingår i: Sensors and Actuators A-Physical. - : Elsevier. - 0924-4247 .- 1873-3069. ; 260, s. 16-23
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Tidskriftsartikel (refereegranskat)abstract
- Wafer bonding methods with ultra-thin intermediate bonding layers are critically important in heterogeneous 3D integration technologies for many NEMS and photonic device applications. A promising wafer bonding approach for 3D integration is adhesive bonding. So far however, adhesive bonding processes relied on relatively thick intermediate adhesive layers. In this paper, we present an adhesive wafer bonding process using an ultra-thin intermediate adhesive layer with sub-200 nm thickness. We demonstrate adhesive bonding of silicon wafers with a near perfect bonding yield of >99% and achieve less than ±10% non-uniformity of the intermediate layer thickness across an entire 100 mm-diameter wafer. A bond strength of 4.8 MPa was measured for our polymer adhesive, which is considerably higher than previously reported for other ultra-thin film adhesives. Additionally, the adhesive polymer used in the proposed method features excellent chemical and mechanical stability. We also report on a potential strategy for mitigating the formation of micro-voids in the polymer adhesive at the bond interface. Furthermore, the polymer adhesive can be sacrificially removed by oxygen plasma etching for both isotropic and anisotropic release etching. The characteristics of the adhesive wafer bonding process and its compatibility with CMOS wafers, makes it very attractive for heterogeneous 3D integration processes targeted at CMOS-integrated NEMS and photonic devices.
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| 50. |
- Bleiker, Simon J., et al.
(författare)
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High-Aspect-Ratio Through Silicon Vias for High-Frequency Application Fabricated by Magnetic Assembly of Gold-Coated Nickel Wires
- 2015
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Ingår i: IEEE Transactions on Components, Packaging, and Manufacturing Technology. - : IEEE Press. - 2156-3950 .- 2156-3985. ; 5:1, s. 21-27
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we demonstrate a novel manufacturing technology for high-aspect-ratio vertical interconnects for high-frequency applications. This novel approach is based on magnetic self-assembly of prefabricated nickel wires that are subsequently insulated with a thermosetting polymer. The high-frequency performance of the through silicon vias (TSVs) is enhanced by depositing a gold layer on the outer surface of the nickel wires and by reducing capacitive parasitics through a low-k polymer liner. As compared with conventional TSV designs, this novel concept offers a more compact design and a simpler, potentially more cost-effective manufacturing process. Moreover, this fabrication concept is very versatile and adaptable to many different applications, such as interposer, micro electromechanical systems, or millimeter wave applications. For evaluation purposes, coplanar waveguides with incorporated TSV interconnections were fabricated and characterized. The experimental results reveal a high bandwidth from dc to 86 GHz and an insertion loss of <0.53 dB per single TSV interconnection for frequencies up to 75 GHz.
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