| 1. |
- Antelius, Mikael, et al.
(författare)
-
Wafer-Level Vacuum Sealing by Coining of Wire Bonded Gold Bumps
- 2013
-
Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 22:6, s. 1347-1353
-
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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| 2. |
- 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
-
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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| 3. |
- Berglund, Martin, et al.
(författare)
-
Operation characteristics and optical emission distribution of a miniaturized silicon through-substrate split-ring resonator microplasma source
- 2014
-
Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 23:6, s. 1340-1345
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Tidskriftsartikel (refereegranskat)abstract
- There are many new microplasma sources being developed for a wide variety of applications, each with different properties tailored to its specific use. Microplasma sources enable portable instruments for, e.g., chemical analysis, sterilization, or activation of substances. A novel microplasma source, based on a microstrip split-ring resonator design with electrodes integrated in its silicon substrate, was designed, manufactured, and evaluated. This device has a plasma discharge gap with a controlled volume and geometry, and offers straightforward integration with other microelectromechancial systems (MEMS) components, e.g., microfluidics. The realized device was resonant at around 2.9 GHz with a quality factor of 18.7. Two different operational modes were observed with the plasma at high pressure being confined in the gap between the electrodes, whereas the plasma at low pressures appeared between the ends of the electrodes on the backside. Measurement of the angular distribution of light emitted from the device with through-substrate electrodes showed narrow emission lobes compared with a reference plasma source with on-substrate electrodes.
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| 4. |
- Bodén, Roger, et al.
(författare)
-
Microdispenser with continuous flow and selectable target volume for microfluidic high-pressure applications
- 2014
-
Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 23:2, s. 452-458
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a reusable microdispenser intended for continuous flow dispensing of variable and controlled volumes of liquid against high back-pressures. The microdispenser consists of two active valves and a dispenser chamber, all actuated by the volume change associated with the solid-to-liquid phase transition of paraffin wax. It is fabricated using stainless steel sheets, a flexible printed circuit board, and a polyimide membrane. All are covered with Parylene C for insulation and fusion bonding at assembly. A finite element method (FEM) model of the paraffin actuator is used to predict the resulting flow characteristics. The results show dispensing of well-defined volumes of 350 and 540 nL, with a good repeatability between dispensing sequences, as well as reproducibility between devices. In addition, the flow characteristics show no back-pressure dependence of the dispensed flow in the interval 0.5--2.0 MPa. The FEM model can be used to predict the flow characteristics qualitatively
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| 5. |
- Braun, Stefan, et al.
(författare)
-
Row/column addressing scheme for large electrostatic actuator MEMS switch arrays and optimization of the operational reliability by statistical analysis
- 2008
-
Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 17:5, s. 1104-1113
-
Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the design and optimization of a row/column addressing scheme to individually pull in or pull out single electrostatic actuators in an N(2) array, utilizing the electromechanical hysteresis behavior of electrostatic actuators and efficiently reducing the number of necessary control lines from N(2) complexity to 2N. This paper illustrates the principle of the row/column addressing scheme. Furthermore, it investigates the optimal addressing voltages to individually pull in or pull out single actuators with maximum operational reliability, determined by the statistical parameters of the pull-in and pull-out characteristics of the actuators. The investigated addressing scheme is implemented for the individual addressing of cross-connect switches in a microelectromechanical systems 20 x 20 switch array, which is utilized for the automated any-to-any interconnection of 20 input signal line pairs to 20 output signal line pairs. The investigated addressing scheme and the presented calculations were successfully tested on electrostatic actuators in a fabricated 20 x 20 array. The actuation voltages and their statistical variations were characterized for different subarray cluster sizes. Finally, the addressing voltages were calculated and verified by tests, resulting in an operational reliability of 99.9498% (502 parts per million (ppm) failure rate) for a 20 x 20 switch array and of 99.99982% (1.75 ppm failure rate) for a 3 x 3 subarray cluster. The array operates by ac-actuation voltage to minimize the disturbing effects by dielectric charging of the actuator isolation layers, as observed in this paper for dc-actuation voltages.
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| 6. |
- Braun, Stefan, et al.
(författare)
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Wafer-Scale Manufacturing of Bulk Shape-Memory-Alloy Microactuators Based on Adhesive Bonding of Titanium-Nickel Sheets to Structured Silicon Wafers
- 2009
-
Ingår i: Journal of microelectromechanical systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1057-7157 .- 1941-0158. ; 18:6, s. 1309-1317
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a concept for the wafer-scale manufacturing of microactuators based on the adhesive bonding of bulk shape-memory-alloy (SMA) sheets to silicon microstructures. Wafer-scale integration of a cold-state deformation mechanism is provided by the deposition of stressed films onto the SMA sheet. A concept for heating of the SMA by Joule heating through a resistive heater layer is presented. Critical fabrication issues were investigated, including the cold-state deformation, the bonding scheme and related stresses, and the titanium-nickel (TiNi) sheet patterning. Novel methods for the transfer stamping of adhesive and for the handling of the thin TiNi sheets were developed, based on the use of standard dicing blue tape. First demonstrator TiNi cantilevers, wafer-level adhesively bonded on a microstructured silicon substrate, were successfully fabricated and evaluated. Intrinsically stressed silicon dioxide and silicon nitride were deposited using plasma-enhanced chemical vapor deposition to deform the cantilevers in the cold state. Tip deflections for 2.5-mm-long cantilevers in cold/hot state of 250/70 and 125/28 mu m were obtained using silicon dioxide and silicon nitride, respectively. The bond strength proved to be stronger than the force created by the 2.5-mm-long TiNi cantilever and showed no degradation after more than 700 temperature cycles. The shape-memory behavior of the TiNi is maintained during the integration process.
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| 7. |
- Briand, D., et al.
(författare)
-
Low-power micromachined MOSFET gas sensor
- 2000
-
Ingår i: Journal of microelectromechanical systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1057-7157 .- 1941-0158. ; 9:3, s. 303-308
-
Tidskriftsartikel (refereegranskat)abstract
- This paper reports on the design, fabrication, and characterization of the first low-power consumption MOSFET gas sensor. The novel MOSFET array gas sensor has been fabricated using anisotropic bulk silicon micromachining. A heating resistor, a diode used as temperature sensor, and four MOSFETs are located in a silicon island suspended by a dielectric membrane. The membrane has a low thermal conductivity coefficient and, therefore, thermally isolates the electronic components from the chip frame. This low thermal mass device allows the reduction of the power consumption to a value of 90 mW for an array of four MOSFETs at an operating temperature of 170 °C. Three of the MOSFETs have their gate covered with thin catalytic metals and are used as gas sensors. The fourth one has a standard gate covered with nitride and could act as a reference. The sensor was tested under different gaseous atmospheres and has shown good gas sensitivities to hydrogen and ammonia. The low-power MOSFET array gas sensor presented is suitable for applications in portable gas sensor instruments, electronic noses, and automobiles.
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| 8. |
- Carlborg, Carl Fredrik, et al.
(författare)
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A High-Yield Process for 3-D Large-Scale Integrated Microfluidic Networks in PDMS
- 2010
-
Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 19:5, s. 1050-1057
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents an uncomplicated high-yield fabrication process for creating large-scale integrated (LSI) 3-D microfluidic networks in poly(dimethylsiloxane) (PDMS). The key innovation lays in the robust definition of miniaturized out-of-plane fluidic interconnecting channels (=vias) between stacked layers of microfluidic channels in standard PDMS. Unblocked vias are essential for creating 3-D microfluidic networks. Previous methods either suffered from limited yield in achieving unblocked vias due to residual membranes obstructing the vias after polymerization, or required complicated and/or manual procedures to remove the blocking membranes. In contrast, our method prevents the formation of residual membranes by inhibiting the PDMS polymerization on top of the mold features that define the vias. In addition to providing unblocked vias, the inhibition process also leaves a partially cured, sticky flat-top surface that adheres well to other surfaces and that allows self-sealing stacking of several PDMS layers. We demonstrate the new method by manufacturing a densely perforated PDMS membrane and an LSI 3-D PDMS microfluidic channel network. We also characterize the inhibition mechanism and study the critical process parameters. We demonstrate that the method is suitable for structuring PDMS layers with a thickness down to 10 mu m.
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| 9. |
- Clausi, Donato, et al.
(författare)
-
Design and wafer-level fabrication of SMA wire microactuators on silicon
- 2010
-
Ingår i: Journal of microelectromechanical systems. - : IEEE Press. - 1057-7157 .- 1941-0158. ; 19:4, s. 982-991
-
Tidskriftsartikel (refereegranskat)abstract
- This paper reports on the fabrication of microactuators through wafer-level integration of prestrained shape memory alloy wires to silicon structures. In contrast to previous work, the wires are strained under pure tension, and the cold-state reset is provided by single-crystalline silicon cantilevers. The fabrication is based on standard microelectromechanical systems manufacturing technologies, and it enables an actuation scheme featuring high work densities. A mathematical model is discussed, which provides a useful approximation for practical designs and allows analyzing the actuators performance. Prototypes have been tested, and the influence of constructive variations on the actuator behavior is theoretically and experimentally evaluated. The test results are in close agreement with the calculated values, and they show that the actuators feature displacements that are among the highest reported.
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| 10. |
- Corman, Thierry, et al.
(författare)
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An optical IR-source and CO2-chamber system for CO2 measurements
- 2000
-
Ingår i: Journal of microelectromechanical systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1057-7157 .- 1941-0158. ; 9:4, s. 509-516
-
Tidskriftsartikel (refereegranskat)abstract
- A new silicon IR-source and CO2-chamber system for measurement of CO2 concentration is presented. The micromachined IR-source, which consists of four groups of polysilicon filaments coated with silicon nitride suspended across a KOH-etched cavity, is used to generate two switched sample and reference beams. The electrically modulated sources present a modulation time of 10 ms and a power consumption of 1 W. The CO2 chambers, placed beneath the reference sources, are used to produce a reference beam for long term stability and compensation against cuvette window contamination. They consist of 1-mm-deep micromachined cavities in which CO2 is encapsulated during an overpressure anodic bonding procedure. Silicon dioxide is used as an antireflective coating to optimize the filter's optical characteristics. Numerical simulations of the filters are presented and show good agreement with the measurements. The IR-sources and the CO2 filters are both fabricated at wafer level. Using the presented IR-sensor system, measurements with a 9-mm-wide test channel show high CO2-sensitivity for CO2 concentrations between 0 and 10% confirming that the stringent requirements for this respirator application can be fulfilled.
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| 11. |
- Decharat, Adit, et al.
(författare)
-
Room-Temperature Sealing of Microcavities by Cold Metal Welding
- 2009
-
Ingår i: Journal of microelectromechanical systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1057-7157 .- 1941-0158. ; 18:6, s. 1318-1325
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present a wafer-to-wafer attachment and sealing method for wafer-level manufacturing of micro-cavities using a room-temperature bonding process. The proposed attachment and sealing method is based on plastic deformation and cold welding of overlapping metal rings to create metal-to-metal bonding and sealing. We present the results from experiments using various bonding process parameters and metal sealing ring designs including their impact on the resulting bond quality. The sealing properties against liquids and vapor of different sealing ring structures have been evaluated for glass wafers that are bonded to silicon wafers. In addition, wafer-level vacuum sealing of microcavities was demonstrated when bonding a silicon wafer to another silicon wafer with the proposed room-temperature sealing and bonding technique.
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| 12. |
- Decharat, Adit, et al.
(författare)
-
Room-temperature sealing of microcavities by cold metal welding
- 2009
-
Ingår i: Journal of microelectromechanical systems. - Piscataway : IEEE. - 1057-7157 .- 1941-0158. ; 18:6, s. 1318-1325
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present a wafer-to-wafer attachment and sealing method for wafer-level manufacturing of micro-cavities using a room-temperature bonding process. The proposed attachment and sealing method is based on plastic deformation and cold welding of overlapping metal rings to create metal-to-metal bonding and sealing. We present the results from experiments using various bonding process parameters and metal sealing ring designs including their impact on the resulting bond quality. The sealing properties against liquids and vapor of different sealing ring structures have been evaluated for glass wafers that are bonded to silicon wafers. In addition, wafer-level vacuum sealing of microcavities was demonstrated when bonding a silicon wafer to another silicon wafer with the proposed room-temperature sealing and bonding technique.
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| 13. |
- Edqvist, Erik, et al.
(författare)
-
Resonating low voltage P(VDF-TrFE) multilayered microactuator built on flexible printed circuit board
-
Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158.
-
Tidskriftsartikel (refereegranskat)abstract
- A resonating low voltage microactuator module is presented and evaluated as conveyer. The characterized module has four cantilevers, of which three are used as legs and one as a sensor. A lithographically patterned flexible printed circuit board acts as the passive part of the cantilever whereas the active part consist of 14 layers of spin coated poly(vinylidenefluoride-trifluoroethylene) with alternating evaporated aluminum electrodes. Among the process steps developed are: a batchwise contacting of the multilayer stack, a batchwise polarization method, and an extended polarization procedure. In the final manufacturing step, the legs are bent 60° out of the plane using a folding equipment. The locomotion module is characterized by connecting it with four copper wires and tested with the legs downwards and upside down against a glass plate. Different weights are added to the module and different driving voltage levels and frequencies are tested. The module was found to operate already at 3.0 V peak-to-peak and capable of forward, backward, right and left movement. With wires attached to it, and using a 80 V peak-to-peak square wave signal at 18020 Hz, it could move 150 mg, which is more than 37 times it own weight.
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| 14. |
- Forsberg, Fredrik, 1980-, et al.
(författare)
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Batch Transfer of Radially Expanded Die Arrays for Heterogeneous Integration Using Different Wafer Sizes
- 2012
-
Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 21:5, s. 1077-1083
-
Tidskriftsartikel (refereegranskat)abstract
- This paper reports on the realization of a novel method for batch transfer of multiple separate dies from a smaller substrate onto a larger wafer substrate by using a standard matrix expander in combination with an elastic dicing tape and adhesive wafer bonding. We demonstrate the expansion and transfer of about 30 000 dies from a 100-mm wafer format to a 200-mm wafer. Furthermore, multiple expansions of 100-mm wafers diced into 60 000 dies are evaluated to determine the position accuracy between different expansions. Fabrication, evaluation method, and results are presented.
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| 15. |
- Ghorbani, Morteza, et al.
(författare)
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On ``Cavitation on Chip'' in Microfluidic Devices With Surface and Sidewall Roughness Elements
- 2019
-
Ingår i: Journal of microelectromechanical systems. - : Institute of Electrical and Electronics Engineers Inc.. - 1057-7157 .- 1941-0158. ; 28:5, s. 890-899
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, cavitating flows are characterized in 29 microfluidic devices in order to achieve a comprehensive perspective regarding flow patterns in microscale, which is crucial in the applications, such as energy harvesting and biomedical treatment. While the assessment of size effects is vital for the design and development of microfluidic devices involving phase change, surface/sidewall roughness and pressure pulses as a result of nanomechanical oscillations increase the performance with respect to cavitation by providing more cavitation bubbles. A typical device generates cavitating flows under different conditions (from inception to choked flow). In this device, a restrictive element and a big channel downstream of the restrictive element--where the cavitation is formed and developed--are included. The cavitating flows are obtained inside 24 sidewall roughened and 5 surface roughened/plain microfluidic devices at different pressure drops. The length and height of the sidewall roughness elements are varied to achieve the most optimum performance in terms of cavitation generation. Moreover, different surface roughened and plain devices are considered to provide a comprehensive overview of cavitation generation in microscale. The results show that sidewall roughness elements have a remarkable effect on the cavitation inception and flow patterns. [2019-0025] IEEE
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| 16. |
- Griss, P., et al.
(författare)
-
Micromachined electrodes for biopotential measurements
- 2001
-
Ingår i: Journal of microelectromechanical systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1057-7157 .- 1941-0158. ; 10, s. 10-16
-
Tidskriftsartikel (refereegranskat)abstract
- We describe the microfabrication, packaging and testing of a micromachined dry biopotential electrode, (i.e., where electrolytic gel is not required). It consists of an array of micro-dimensioned, very sharp spikes, (i.e., needles) designed for penetration of human skin which circumvent high impedance problems associated with layers of tbe outer skin. The spikes are etched in silicon by deep reactive ion etching and are subsequently covered with a silver-silverchloride (Ag-AgCl) double layer. The electrode-skin-electrode impedance of dry spiked electrodes having a size of 4 x 4 mm(2) is reduced compared to standard electrodes using electrolytic gel and having a comparable size, Recorded low amplitude biopotentials resulting from the activity of the brain, (i.e, EEG signals) are of high quality, even for spiked electrodes as small as 2 x 2 mm(2). The spiked electrode offers a promising alternative to standard electrodes in biomedical applications and is of interest in research of nem biomedical methods.
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| 17. |
- Griss, Patrick, et al.
(författare)
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Side-opened out-of-plane microneedles for microfluidic transdermal liquid transfer
- 2003
-
Ingår i: Journal of microelectromechanical systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1057-7157 .- 1941-0158. ; 12:3, s. 296-301
-
Tidskriftsartikel (refereegranskat)abstract
- We present the first hollow out-of-wafer-plane silicon microneedles having openings in the shaft rather than having an orifice at the tip. These structures are well suited for transdermal microfluidic applications, e.g., drug or vaccine delivery. The developed deep-reactive ion etching (DRIE) process allows fabrication of two dimensional, mechanically highly resistant needle arrays offering low resistance to liquid flows and a large exposure area between the fluid and the tissue. The presented process does not require much wafer handling and only two photolithography steps are required. Using a 3 x 3 mm(2) chip in a typical application, e.g., vaccine delivery, a 100 mul volume of aqueous fluid injected in 2 s would cause a pressure drop of less than 2 kPa. The presented needles are approximately 210 mum long.
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| 18. |
- Haasl, Sjoerd, et al.
(författare)
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Hybrid-mounted micromachined aluminum hotwires for wall shear-stress measurements
- 2005
-
Ingår i: Journal of microelectromechanical systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1057-7157 .- 1941-0158. ; 14:2, s. 254-260
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present a micromachined metal hotwire anemometer sensor for use in wall shear-stress measurements. We describe its design and fabrication. A novel hybrid assembly method has been developed to make it possible to measure close to the surface without contacting leads interfering with the flow. Experimental results illustrate the behavior and characteristics of this sensor.
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| 19. |
- Haasl, Sjoerd, et al.
(författare)
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Out-of-Plane Knife-Gate Microvalves for Controlling Large Gas Flows
- 2006
-
Ingår i: Journal of microelectromechanical systems. - : IEEE Press. - 1057-7157 .- 1941-0158. ; 15:5, s. 1281-1288
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Tidskriftsartikel (refereegranskat)abstract
- This paper considers design issues for microvalves for large gas flow control. It introduces out-of-plane knife-gate microvalves as a novel design concept and a proportional microvalve concept for pressure control applications. The design of three different actuator-gate configurations and first prototypes are presented. The first valve prototypes feature thermal silicon-aluminum bimorph actuators and the pressure-flow performance per chip area of the demonstrator valve presented is greatly increased using out-of-plane actuation and an out-of-plane orifice. The characterization of the actuators and of the pressure-flow performance is presented. The prototype valve allows for a flow change of Delta Q = 3.4 standard liters per minute (SLPM) at a pressure change of Delta P = 95 kPa (P-in = 196.3 kPa, P-out = 101.3 kPa) on an active chip area of only 2.3 x 3.7 mm(2).
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| 20. |
- Ke, Feixiang, et al.
(författare)
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A Ruthenium-Based Multimetal-Contact RF MEMS Switch With a Corrugated Diaphragm
- 2008
-
Ingår i: Journal of microelectromechanical systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1057-7157 .- 1941-0158. ; 17:6, s. 1447-1459
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a ruthenium metal-contact RF microelectromechanical system switch based on a corrugated silicon oxide/silicon nitride diaphragm. The corrugations are designed to substantially reduce the influence of the fabrication-induced stress in the membrane, resulting in a highly insensitive design to process parameter variations. Furthermore, a novel multilayer metal-contact concept, comprising a 50-nm chromium/50-nm ruthenium/500-nm gold/50-nm ruthenium structure, is introduced to improve the contact reliability by having a hard-metal surface of ruthenium without substantial compromise in the contact and transmission-line resistances, which is shown by theoretical analysis of the contact physics and confirmed by measurement results. The contact resistance of the novel metallization stack is investigated for different contact pressures and is compared to pure-gold contacts. The contact reliability is investigated for different do signal currents. At a measurement current of 1.6 mA, the Ru-Au-Ru contacts have an average lifetime of about 100 million cycles, whereas the Au-Au contacts reach 24 million cycles only. For larger signal currents, the metal contacts have proven to be more robust over the Au-Au contacts by a factor of ten. The measured pull-in voltage is reduced significantly from 61 V for flat diaphragm to 36 V for corrugated diaphragm with the introduction of corrugation. The measured RF isolation with a nominal contact separation of 5 mu m is better than -30 dB up to 4 GHz and still -21 dB at 15 GHz, whereas the insertion loss of the fully packaged switch including its transmission line is about -0.7 dB up to 4 GHz and -2.8 dB at 15 GHz.
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| 21. |
- Lapisa, Martin, et al.
(författare)
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Drift-free micromirror arrays made of monocrystalline silicon for adaptive optics applications
- 2012
-
Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 21:4, s. 959-970
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we report on the heterogeneous integration of monocrystalline silicon membranes for the fabrication of large segmented micromirror arrays for adaptive optics applications. The design relies on a one-level architecture with mirrors and suspension formed within the same material, employing a large actuator gap height of up to 5.1 μ m to allow for a piston-type mirror deflection of up to 1600 nm. Choosing monocrystalline silicon as actuator and mirror material, we demonstrate a completely drift-free operation capability. Furthermore, we investigate stress effects that degrade the mirror topography, and we show that the stress originates from the donor silicon-on-insulator wafer. The novel heterogeneous integration strategy used in this work is capable of reducing this stress to a large extent.
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| 22. |
- Last, Torben, et al.
(författare)
-
3D-Printing Enables Fabrication of Swirl Nozzles for Fast Aerosolization of Water-Based Drugs
- 2021
-
Ingår i: Journal of microelectromechanical systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1057-7157 .- 1941-0158. ; 30:2, s. 181-183
-
Tidskriftsartikel (refereegranskat)abstract
- Portable inhalers are used for delivering drugs to the lung in the form of aerosols and form the standard treatment for diseases such as Asthma, COPD, and cystic fibrosis. However, for aqueous drug formulations, spray nozzle chips have so far been restricted to cleanroom manufacture due to their small feature sizes. Here we present a spring-actuated 3D-printed swirl nozzle that sprays an aqueous drug solution, matching propellant-containing inhalers in aerosolization time. The use of two-photon polymerization enables the small nozzle feature size of 100 mu m and device print times of only 4 min, making serial mass-fabrication a viable option. Our 35 bar spring-operated swirl nozzle prototype achieves mean volumetric particle sizes of 12.5 mu m on doses of 100 mu l, aerosolized in 270 ms, as fast as a propellant-driven inhaler. [2021-0002]
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| 23. |
- Last, Torben, et al.
(författare)
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A Self-Sealing Spray Nozzle for Aerosol Drug Delivery
- 2020
-
Ingår i: Journal of microelectromechanical systems. - : IEEE. - 1057-7157 .- 1941-0158. ; 29:2, s. 182-189
-
Tidskriftsartikel (refereegranskat)abstract
- Chronic lung disease is commonly treated using portable inhaler systems. By design, these inhalers come into repeated contact with the mouth region of patients and are therefore subject to bacterial contamination and ingrowth. To enable the safe delivery of an aerosol from a drug reservoir of such an inhaler, the reservoir needs to be protected from pathogens. Here we demonstrate a self-sealing aerosol spray nozzle, a system that seals each spray orifice on nozzle level in its default closed state and sprays a liquid Rayleigh-jet upon actuation. The sealing mechanism is realized by placing a thin membrane with spray orifices on top of a valve seat. The membrane behavior and spray performance of the self-sealing spray chip were found to be identical to an equivalent non-sealing design. This sealing system may enable the safe reuse of spray chips for multiple spray operations over an extended period, lowering the cost of treatment while increasing patient compliance.
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| 24. |
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| 25. |
- Lehto, Marcus, et al.
(författare)
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A polymeric paraffin microactuator
- 2008
-
Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 17:5, s. 1172-1177
-
Tidskriftsartikel (refereegranskat)abstract
- Paraffin wax is a promising material in microactuators not only because of its ability of producing large displacements and high forces at the same time but also because of the variety of manufacturing techniques available. In this paper, a simple actuator based on paraffin wax as the active material is fabricated and tested. Ultraviolet-curable epoxy is used in a technique combining simultaneous moulding and liquid-phase photopolymerization in a single-process step to build the stiff part of the actuator body. A heater is integrated in the paraffin reservoir, and a polyimide tape is used as the deflecting membrane. Thermornechanical analysis of the paraffin wax shows that it exhibits a volume expansion of 10%, including phase transitions and linear expansion. As for the actuator, a stroke of 90 mu m is obtained for the unloaded device, whereas 37 mu m is recorded with a 0.5-N contact load at a driving voltage of 0.71 V and a frequency of 1/32 Hz. The actuator can be used in microsystems, where both large strokes and forces are needed. The low-cost materials and low driving voltage also makes it suitable for disposable systems.
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| 26. |
- Lehto, Marcus, et al.
(författare)
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Binary mixtures of n-alkanes for tunable thermohydraulic microactuators
- 2007
-
Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 16:3, s. 728-733
-
Tidskriftsartikel (refereegranskat)abstract
- The two objectives of this paper are related to the use of n-alkanes in actuators. The first objective is to study the thermomechanics of binary mixtures of dotriacontane and hexatriacontane to see if a quasi-stable thermal expansion can be obtained, and the second one is to find the correspondence between dilatometry [pressure, volume, and temperature (pVT) measurement] and differential scanning calorimetry (DSC). Results show that there is indeed a concentration-dependent plateau in the expansion curves and that the width and horizontal position of this can be adjusted. As compared with pure n-alkanes, the plateaus of the mixtures widen by a factor of 2-4, and as compared with pure hexatriacontane, they shift their low-end temperatures by 5 °C to 10 °C, in the 25% to 75% concentration range. The mixtures' plateaus (gathered around 0.06 cm3/g) are about 0.02 cm3/g below those of the pure n-alkanes. It is shown that DSC can be used for a prediction of the thermomechanical properties of the substances, provided that a pVT reference exists, and the fact that the melting point increases with the pressure that is experienced with the dilatometer is considered. The qualitative similarity between the expansion and enthalpy curves is remarkable. About 25% to 30% of the total volume expansion is attributed to the solid-to-solid phase transition; the rest is attributed to thermal expansion and melting.
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| 27. |
- Lehto, Marcus, et al.
(författare)
-
Rapid prototyping of a polymeric paraffin microactuator
- 2008
-
Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 17:5, s. 1172-1177
-
Tidskriftsartikel (refereegranskat)abstract
- Paraffin wax is a promising material in microactuators not only because of its ability of producing large displacements and high forces at the same time but also because of the variety of manufacturing techniques available. In this paper, a simple actuator based on paraffin wax as the active material is fabricated and tested. Ultraviolet-curable epoxy is used in a technique combining simultaneous moulding and liquid-phase photopolymerization in a single-process step to build the stiff part of the actuator body. A heater is integrated in the paraffin reservoir, and a polyimide tape is used as the deflecting membrane. Thermomechanical analysis of the paraffin wax shows that it exhibits a volume expansion of 10%, including phase transitions and linear expansion. As for the actuator, a stroke of 90 mum is obtained for the unloaded device, whereas 37 mum is recorded with a 0.5-N contact load at a driving voltage of 0.71 V and a frequency of 1/32 Hz. The actuator can be used in microsystems, where both large strokes and forces are needed. The low-cost materials and low driving voltage also makes it suitable for disposable systems.
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| 28. |
- Lin, Chih-Ming, et al.
(författare)
-
Micromachined One-Port Aluminum Nitride Lamb Wave Resonators Utilizing the Lowest-Order Symmetric Mode
- 2013
-
Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 23:1, s. 78-91
-
Tidskriftsartikel (refereegranskat)abstract
- The characteristics of one-port aluminum nitride (AlN) Lamb wave resonators utilizing the lowest symmetric (S0) mode with electrically open, grounded, and floating bottom electrode configurations are theoretically and experimentally investigated. The finite element analysis (FEA) is performed to take an insight into the static capacitance characteristics of the AlN Lamb wave resonators with various bottom surface conditions. The theoretical results predict that the floating bottom electrode efficiently reduces the static capacitance in the AlN thin plate and then promotes an efficient improvement in the effective coupling coefficient. Experimentally the AlN Lamb wave resonator without a bottom electrode exhibits a loaded quality factor (Q) as high as 3033 at its series resonance frequency, 948.1 MHz, but a low effective coupling coefficient of 0.18%. On the contrary, the Lamb wave resonator with an electrically floating bottom electrode shows an effective coupling coefficient up to 1.05% but a low loaded Q of 850 at its series resonance frequency, 850.3 MHz. In contrast to the floating bottom electrode, the Lamb wave resonator with an electrically grounded bottom electrode shows a smaller effective coupling coefficient of 0.78% and a similar loaded Q of 800 at the series resonance frequency, 850.5 MHz.
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| 29. |
- Malik, Amer, et al.
(författare)
-
Modeling and analysis of a phase change material thermohydraulic membrane microactuator
- 2013
-
Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 22:1, s. 186-194
-
Tidskriftsartikel (refereegranskat)abstract
- Presented in this work, is a Finite Element Method (FEM)-based model for phase change material actuators, modeling the active material as a fluid as opposed to a solid. This enables the model to better conform to localized loads, as well as offering the opportunity to follow material movement in enclosed volumes. Modeling, simulation and analysis of an electrothermally activated paraffin microactuator has been conducted. The paraffin microactuator used for the analysis in the current study exploits the large volumetric expansion of paraffin upon melting, which combined with its low compressibility in the liquid state allows for high hydraulic pressures to be generated. The purpose of the study is to supply a geometry independent model of such a microactuator through the implementation of a fluid model rather than a solid model, which has been utilized in previous studies. Numerical simulations are conducted at different frequencies of the heating source and for different geometries of the microactuator. The results are compared with the empirical data obtained on a close to identical paraffin microactuator, which clearly show the advantages of a fluid model instead of a solid state approximation.
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| 30. |
- Melvås, Patrik, et al.
(författare)
-
A surface-micromachined resonant-beam pressure-sensing structure
- 2001
-
Ingår i: Journal of microelectromechanical systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1057-7157 .- 1941-0158. ; 10:4, s. 498-502
-
Tidskriftsartikel (refereegranskat)abstract
- The first study on an entirely surface-micromachined resonant-beam pressure sensor is presented. Using a fully surface-micromachined process, an encapsulated beam resonant pressure-sensor structure with a pressure-sensitive diaphragm of 100 x 150 x 2 mum has been fabricated. The resonating beam is fully enclosed inside the reference vacuum cavity formed beneath the diaphragm. The new design enables high pressure sensitivity and a miniature chip size, essential for sensors such as catheter-mounted intravascular blood pressure sensors. The pressure sensitivity is measured at 3.2 %/bar with a beam resonance frequency of about 700 kHz.
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| 31. |
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| 32. |
- Nafari, Alexandra, 1980, et al.
(författare)
-
MEMS Sensor for in Situ TEM Atomic Force Microscopy
- 2008
-
Ingår i: Journal of microelectromechanical systems. - : IEEE Press. - 1057-7157 .- 1941-0158. ; 17:2, s. 328-333
-
Tidskriftsartikel (refereegranskat)abstract
- Here, we present a MEMS atomic force microscope sensor for use inside a transmission electron microscope (TEM). This enables direct in situ TEM force measurements in the nanonewton range and thus mechanical characterization of nanosized structures. The main design challenges of the system and sensor are to reach a high sensitivity and to make a compact design that allows the sensor to be fitted in the narrow dimensions of the pole gap inside the TEM. In order to miniaturize the sensing device, an integrated detection with piezoresistive elements arranged in a full Wheatstone bridge was used. Fabrication of the sensor was done using standard micromachining techniques, such as ion implantation, oxide growth and deep reactive ion etch. We also present in situ TEM force measurements on nanotubes, which demonstrate the ability to measure spring constants of nanoscale systems.
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| 33. |
- Niklaus, Frank, et al.
(författare)
-
Arrays of monocrystalline silicon micromirrors fabricated using CMOS compatible transfer bonding
- 2003
-
Ingår i: Journal of microelectromechanical systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1057-7157 .- 1941-0158. ; 12:4, s. 465-469
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present CMOS compatible fabrication of monocrystalline silicon micromirror arrays using membrane transfer bonding. To fabricate the micromirrors, a thin monocrystalline silicon device layer is transferred from a standard silicon-on-insulator (SOI) wafer to a target wafer (e.g., a CMOS wafer) using low-temperature adhesive wafer bonding. In this way, very flat, uniform and low-stress micromirror membranes made of monocrystalline silicon can be directly fabricated on top of CMOS circuits. The mirror fabrication does not contain any bond alignment between the wafers, thus, the mirror dimensions and alignment accuracies are only limited by the photolithographic steps. Micromirror arrays with 4 x 4 pixels and a pitch size of 16 mum x 16 mum have been fabricated. The monocrystalline silicon micromirrors are 0.34 mum thick and have feature sizes as small as 0.6 mum. The distance between the addressing electrodes and the mirror membranes is 0.8 mum. Torsional micromirror arrays are used as spatial light modulators, and have potential applications in projection display systems, pattern generators for maskless lithography systems, optical spectroscopy, and optical communication systems. In principle, the membrane transfer bonding technique can be applied for integration of CMOS circuits with any type of transducer that consists of membranes and that benefits from the use of high temperature annealed or monocrystalline materials. These types of devices include thermal infrared detectors, RF-MEMS,IS devices, tuneable vertical cavity surface emitting lasers (VCSEL) and other optical transducers.
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| 34. |
- Niklaus, Frank, et al.
(författare)
-
Low-temperature wafer-level transfer bonding
- 2001
-
Ingår i: Journal of microelectromechanical systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1057-7157 .- 1941-0158. ; 10:4, s. 525-531
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present a new wafer-level transfer bonding technology. The technology can be used to transfer devices or films from one substrate wafer (sacrificial device wafer) to another substrate wafer (target wafer). The transfer bonding technology includes only low-temperature processes; thus, it is compatible with integrated circuits. The process flow consists of low-temperature adhesive bonding followed by sacrificially thinning of the device wafer. The transferred devices/films can be electrically interconnected to the target wafer (e.g., a CMOS wafer) if required. We present three example devices for which we have used the transfer bonding technology. The examples include two polycrystalline silicon structures and a test device for temperature coefficient of resistance measurements of thin-film materials. One of the main advantages of the new transfer bonding technology is that transducers and integrated circuits can be independently processed and optimized on different wafers before integrating the transducers on the integrated circuit wafer. Thus, the transducers can be made of, e.g., monocrystalline silicon or other high-temperature annealed, high-performance materials. Wafer-level transfer bonding can be a competitive alternative to flip-chip bonding, especially for thin-film devices with small feature sizes and when small electrical interconnections (< 3 x 3 mum(2)) between the devices and the target wafer are required.
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| 35. |
- Oberhammer, Joachim, et al.
(författare)
-
Active opening force and passive contact force electrostatic switches for soft metal contact materials
- 2006
-
Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 15:5, s. 1235-1242
-
Tidskriftsartikel (refereegranskat)abstract
- This paper reports on a mechanically bi-stable, electrostatically actuated switch mechanism with a large active opening force and a small passive closing force, designed to fit the contact and opening force requirements of soft contact materials such as gold. So far, most microelectromechanical systems (MEMS) switch designs have been optimized for a large contact force without paying too much attention to the opening force. In the conventional, most commonly used electrostatic microswitch concept, the force of the actuator is used to close the switch contacts, and the switch is opened by the passive restoring force of the deflected cantilever or membrane. This concept results in a large contact force, but the opening force is typically too small to overcome the contact adhesion force of soft metals, which makes this concept less suitable for contact materials such as gold with its low contact resistance at low contact forces. The switch concept presented in this paper is based on two cantilevers laterally moving by curved electrode actuators. The tips of the cantilevers are endowed with hooks which can be mechanically interlocked. In the latched state, the spring forces of the deflected cantilevers also act as the passive contact force between the switch contacts. The opening force is actively created by the curved-electrode actuators, which are utilized close to their best electromechanical operating point resulting in a maximum contact separation force. The theoretical discussion of the new concept as compared to conventional switch designs is supported by simulation results, measurements on fabricated devices, and by an analysis of exemplary switches published in the literature.
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| 36. |
- Oberhammer, Joachim, et al.
(författare)
-
BCB contact printing for patterned adhesive full-wafer bonded 0-level packages
- 2005
-
Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 14:2, s. 419-425
-
Tidskriftsartikel (refereegranskat)abstract
- Adhesive water bonding with a patterned polymer layer is increasingly attracting attention as cheap and simple 0-level packaging technology for microstructures, because the patterned polymer both fulfills the bonding function and determines the volumes between the two wafers housing the devices to be packaged. To be able to pattern a polymer, it has to be cross-linked to a certain degree which makes the material rigid and less adhesive for the bonding afterward. In this paper, a simple method is presented which combines the advantages of a patterned adhesive layer with the advantages of a liquid polymer phase before the bonding. The pattern in the adhesive layer is "inked" with viscous polymer by pressing the substrate toward an auxiliary wafer with a thin liquid polymer layer. Then, the substrate with the inked pattern is finally bonded to the top wafer. Benzocyclobuene (BCB) was used both for the patterned structures and as the "ink". Tensile bond strength tests were carried out on patterned adhesive bonded samples fabricated with and without this contact printing method. The bonding yield is significantly improved with the contact printing method, the fabrication procedure is more robust and the test results show that the bond strength is at least 2 times higher. An investigation of the samples' failure mechanisms revealed that the bond strength even exceeds the adhesion forces of the BCB to the substrate. Furthermore, the BCB contact printing method was successfully applied for 0-level glass-lid packaging done by full-wafer bonding with a patterned adhesive layer. Here, the encapsulating lids are separated after the bonding by dicing the top wafer independently of the bottom wafer.
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| 37. |
- Oberhammer, Joachim, et al.
(författare)
-
Design and fabrication aspects of an S-shaped film actuator based DC to RF MEMS switch
- 2004
-
Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 13:3, s. 421-428
-
Tidskriftsartikel (refereegranskat)abstract
- This paper reports on design and fabrication aspects of a new microelectromechanical series switch for switching de and RF signals. The switch consists of a flexible S-shaped film with the switching contact, rolling between a top and a bottom electrode in electrostatic touch-mode actuation. This design allows a low actuation voltage independent of the contact distance in the off-state. With a large contact distance, large overlapping switching contact areas are possible by obtaining a high off-state isolation. The RF transmission line and the MEMS part of the switch are fabricated on separate wafers, allowing an implementation of the switch with different RF substrates. The final assembly is done on device level for the first prototypes, even though the design provides the possibility of an assembly by full wafer bonding, leading to a near-hermetic package integrated switch. The measured prototype actuation voltages are 12 V to open and 15.8 V to close the contacts, with a resistance of 275 mOmega of each contact at an estimated contact force of 102 muN. The measured RF isolation with a contact distance of 14.2 mum is better than -45 dB up to 2 GHz and -30 dB at 15 GHz, at a large nominal switching contact area of 3500 mum(2).
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| 38. |
- Oberhammer, Joachim, et al.
(författare)
-
Time-efficient quasi-static algorithm for simulation of complex single-sided clamped electrostatic actuators
- 2007
-
Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 16:2, s. 373-382
-
Tidskriftsartikel (refereegranskat)abstract
- This paper reports on a very time- and resource-efficient numerical algorithm for quasi-static modeling of the static behavior and the quasi-static movement of highly nonlinear electrostatic actuators with single-side clamped moving elements. The algorithm is capable of simulating prestressed materials and multicontact touching surfaces with complex geometries, including distance-keeping stoppers and thickness and material inhomogeneities of the moving parts. Thus, it is very suitable for predicting the behavior of actuators such as laterally moving curved-electrode actuators or vertically moving touch-mode or zipper actuators. In contrast to conventional, very time- and memory-consuming simulation methods such as finite-element analysis, the proposed algorithm-even if implemented in the slow script-language of MATLAB-takes only a fraction of a second to solve a complex problem, which makes it a very powerful design tool for parameter optimization of the actuator geometry. The reason for the efficiency of this algorithm is that its core is based on the one-dimensional mathematical description of a two-dimensional model geometry and that the differential equation is solved by a simple triple-integration for each iteration step, which is a method very suitable for thin-film single-side clamped moving elements. This paper describes the algorithm, analyzes its accuracy and its limitations, and reports on its performance as compared to other methods such as simplified analytical models for very basic structures, finite-element method (FEM) simulations of complex structures, and measurements of fabricated devices, including laterally moving microelectromechanical systems (MEMS) switches and vertically closing prestressed thin-film zipper actuators. Furthermore, the efficiency of the algorithm as a design tool was evaluated for the parameter optimization of electrostatic curved-electrode actuators. The algorithm's main application is seen in the fast determination of suitable parameter sets for MEMS electrostatic actuators, but it cannot substitute for a more accurate FEM analysis to investigate a final design in great detail.
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| 39. |
- Ogden, Sam, 1979-, et al.
(författare)
-
A Latchable Valve for High-Pressure Microfluidics
- 2010
-
Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 19:2, s. 396-401
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, the strongest yet latchable valve in subcubic-centimeter size for microfluidic applications is presented. The device has an integrated actuator cavity consisting of three segments filled with paraffin, each operated by a separate heater. At one of the segments, a membrane valve head is deflected by the expansion of the resistively melted paraffin to close against its valve seat. Different heating sequences provide a latched closed or opened valve. The maximum pressure before any leakage occurred was 2.5 MPa. The leak pressure is found to be progressively dependent on the clamping pressure applied. The valve has an opening and closing time of 7 and 1 s, respectively. At an applied pressure of 0.3 MPa, the closed valve needs to be reactivated every 100 min to remain leakage free, leading to an average power consumption of 4.5 mW.
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| 40. |
|
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| 41. |
- Rahiminejad, Sofia, et al.
(författare)
-
Polymer Gap Adapter for Contactless, Robust, and Fast Measurements at 220-325 GHz
- 2016
-
Ingår i: Journal of microelectromechanical systems. - : IEEE Press. - 1057-7157 .- 1941-0158. ; 25:1, s. 160-169
-
Tidskriftsartikel (refereegranskat)abstract
- Radiation leakages are a considerable problem when measuring waveguide structures at high frequencies. In order to maintain good electrical contact, flanges need to be tightly and evenly screwed to the device under test. This can be a time-consuming operation, especially with repeated measurements. We present a metamaterial-based adapter, which prohibits leakage even in the presence of gaps at the interconnects. This so-called gap adapter has been fabricated from a metallized polymer (SU8). The reflection coefficient is below -20 dB throughout the band for a 50-mu m gap on both sides of the gap adapter. In comparison, a conventional waveguide with a 50-mu m gap on both sides has a reflection coefficient of -10 dB. The gap adapter can be used to perform fast measurements, since the normal flange screws are redundant. We compare the SU8 gap adapter with a Si version and to a smooth metal waveguide reference disc. The SU8 gap adapter performed better than the Si version and much better than the waveguide disc in all test cases. SU8 gap adapters were used to measure on a waveguide component. The SU8 gap adapters with 50-mu m gaps performed comparable with the waveguide component with the flange screws carefully tightened. The polymer also makes the gap adapter mechanically robust and easy to mass fabricate. [2015-0113]
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| 42. |
- Rahiminejad, Sofia, 1987, et al.
(författare)
-
Polymer Gap Adapter for Contactless, Robust, and Fast Measurements at 220-325 GHz
- 2016
-
Ingår i: Journal of Microelectromechanical Systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1057-7157 .- 1941-0158. ; 25:1, s. 160-169
-
Tidskriftsartikel (refereegranskat)abstract
- Radiation leakages are a considerable problem when measuring waveguide structures at high frequencies. In order to maintain good electrical contact, flanges need to be tightly and evenly screwed to the device under test. This can be a time-consuming operation, especially with repeated measurements. We present a metamaterial-based adapter, which prohibits leakage even in the presence of gaps at the interconnects. This so-called gap adapter has been fabricated from a metallized polymer (SU8). The reflection coefficient is below -20 dB throughout the band for a 50-mu m gap on both sides of the gap adapter. In comparison, a conventional waveguide with a 50-mu m gap on both sides has a reflection coefficient of -10 dB. The gap adapter can be used to perform fast measurements, since the normal flange screws are redundant. We compare the SU8 gap adapter with a Si version and to a smooth metal waveguide reference disc. The SU8 gap adapter performed better than the Si version and much better than the waveguide disc in all test cases. SU8 gap adapters were used to measure on a waveguide component. The SU8 gap adapters with 50-mu m gaps performed comparable with the waveguide component with the flange screws carefully tightened. The polymer also makes the gap adapter mechanically robust and easy to mass fabricate. [2015-0113]
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| 43. |
- Roxhed, Niclas, et al.
(författare)
-
Penetration-enhanced ultrasharp microneedles and prediction on skin interaction for efficient transdermal drug delivery
- 2007
-
Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 16:6, s. 1429-1440
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents penetration-enhanced hollow microneedles and an analysis on the biomechanical interaction between microneedles and skin tissue. The aim of this paper is to fabricate microneedles that reliably penetrate the skin tissue without using penetration enhancers or special insertion tools that were used in the previous studies. The microneedles are made of silicon and feature ultrasharp tips and side openings. The microneedle chips were experimentally tested in vivo by injection of dye markers. To further investigate the penetration, the insertion progression and the insertion force were monitored by measuring the electrical impedance between microneedles and a counter electrode on the skin. The microneedle design was also tested using a novel simulation approach and compared to other previously published microneedle designs. The purpose of this specific part of the paper was to investigate the interaction mechanisms between a microneedle and the skin tissue. This investigation is used to predict how the skin deforms upon insertion and how microneedles can be used to create a leak-free liquid delivery into the skin. The fabricated microneedles successfully penetrated dry living human skin at all the tested sites. The insertion characteristic of the microneedle was superior to an earlier presented type, and the insertion force of a single microneedle was estimated to be below 10 mN. This low insertion force represents a significant improvement to earlier reported results and potentially allows a microneedle array with hundreds of needles to be inserted into tissue by hand.
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| 44. |
|
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| 45. |
- Samel, Björn, et al.
(författare)
-
A Thermally Responsive PDMS Composite and its Microfluidic Applications
- 2007
-
Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 16:1, s. 50-57
-
Tidskriftsartikel (refereegranskat)abstract
- This paper describes a novel composite actuator for controlled liquid actuation in microsystems which is based on a thermally responsive elastomer. The composite actuator consists of expandable microspheres incorporated in a polydimethylsiloxane (PDMS) matrix and entails the merits of both PDMS and expandable microspheres. The main characteristic of the composite actuator is to expand upon heat. The expansion is irreversible and the relative volume increase is measured up to 270% of its original volume after heating to 80 degrees C. The composite was used to fabricate single-use microfluidic pumps and valves. We show the displacement of liquids in the range of nanoliters even against counter pressures up to 100 kPa. Moreover, liquid flow in microchannels was entirely blocked by means of the integrated valves. The valves can withstand pressures up to 140 kPa. The devices are fabricated using low-cost materials only, and the composite actuator allows using wafer-level processing. The fluidic components based on the novel composite are highly integrable and do not require external actuators.
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| 46. |
- Samel, Björn, et al.
(författare)
-
Liquid Aspiration and Dispensing Based on an Expanding PDMS Composite
- 2008
-
Ingår i: Journal of microelectromechanical systems. - : IEEE Press. - 1057-7157 .- 1941-0158. ; 17:5, s. 1254-1262
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present the development of active liquid aspiration and dispensing units designed for vertical, as well as lateral, liquid aspiration. The devices are based on a single-use thermally expanding polydimethylsiloxane (PDMS) composite, which allows altering its surface topography by means of individually addressable integrated heaters. Devices are designed in order to create an enclosed cavity in the system, due to locally expanding the initially unstructured composite. This enables negative volume displacement and leads to the event of liquid aspiration. To enable this device functionality, two different techniques of selectively creating permanent PDMS bonds have been developed. One approach utilizes the plasma-assisted PDMS bonding technique, together with a patterned antistiction layer to form reversibly, as well as irreversibly, bonded regions. Another approach utilizes microcontact printing of PDMS curing agent, which serves as a patterned intermediate layer for adhesive bonding. Fabricated prototype devices successfully demonstrated the aspiration and release of liquid volumes ranging from 28 to 815 nL. The devices are entirely fabricated from low-cost materials, using wafer-level processes only and do not require external means for liquid actuation.
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| 47. |
- Samel, Björn, et al.
(författare)
-
Wafer-Level Process for Single-Use Buckling Film Microliter-Range Pumps
- 2007
-
Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 16:4, s. 795-801
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present the development of disposable single-use microfluidic pumps entirely based on a straightforward wafer-level fabrication scheme, which allows for precise integrated active dosing in the microliter range. To accomplish stroke-lengths needed for microliter-range applications, we utilize a new method of bending of a unimorph-composite-actuator film. The unimorph composite actuator consists of a temperature-sensitive silicone elastomer composite, i.e., polydimethylsiloxane, with incorporated expandable microspheres. The fabricated micropumps successfully demonstrated precise liquid-volume control, both at low and high flow rates, and show a standard deviation of 6.7% for consecutive pump experiments. Moreover, the method of fluorescent thermometry was used to measure the thermal load on liquid volumes dispensed with the micropumps. The liquid temperature reaches a maximum of 50 degrees C during the operation. The presented fully integrated single-use micropumps are electrically controllable, do not require external means for liquid actuation, are made of low-cost materials only, and might potentially be used in drug-delivery applications.
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| 48. |
- Schroeder, Jeremy L., et al.
(författare)
-
Bulk-Like Laminated Nitride Metal/Semiconductor Superlattices for Thermoelectric Devices
- 2014
-
Ingår i: Journal of microelectromechanical systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1057-7157 .- 1941-0158. ; 23:3, s. 672-680
-
Tidskriftsartikel (refereegranskat)abstract
- Bulk-like thermionic energy conversion devices have been fabricated from nanostructured nitride metal/semiconductor superlattices using a novel lamination process. 5-mu m thick (Hf0.5Zr0.5)N (6-nm)/ScN (6-nm) metal/semiconductor superlattices with a 12 nm period were deposited on 100-silicon substrates by reactive magnetron sputtering followed by a selective tetra methyl ammonium hydroxide substrate etching and a gold-gold lamination process to yield 300 mu m x 300 mu m x 290 mu m microscale thermionic energy conversion elements with 16,640 superlattice periods. The thermionic element had a Seebeck coefficient of -120 mu V/K at 800 K, an electrical conductivity of similar to 2500 Omega(-1)m(-1) at 800 K, and a thermal conductivity of 2.9 and 4.3 W/m-K at 300 and 625 K, respectively. The temperature dependence of the Seebeck coefficient from 300 to 800 K suggests a parallel parasitic conduction path that is dominant at low temperature, and the temperature independent electrical conductivity indicates that the (Hf0.5Zr0.5)N/gold interface contact resistivity currently dominates the device. The thermal conductivity of the laminate was significantly lower than the thermal conductivity of the individual metal or semiconductor layers, indicating the beneficial effect of the metal/semiconductor interfaces toward lowering the thermal conductivity. The described lamination process effectively bridges the gap between the nanoscale requirements needed to enhance the thermoelectric figure of merit ZT and the microscale requirements of real-world devices.
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| 49. |
- Schröder, Stephan, et al.
(författare)
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Stress-Minimized Packaging of Inertial Sensors by Double-Sided Bond Wire Attachment
- 2015
-
Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 24:4, s. 781-789
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a novel approach for low-stress packaging of microelectromechanical system (MEMS)-based gyroscopes. The proposed approach makes use of conventional ball-stitch wire bonding. The gyroscope die is attached exclusively by means of bond wire connections between the package frame, and the top and bottom surfaces of the die. The process enables the electrical connection of metal pads on the top and the bottom side of the MEMS die within the same process. No adhesives, glue, or solder is used for the die attach. The stiffness of the proposed die attach is evaluated by scanning laser Doppler vibrometry. White-light interferometry is used to investigate stress in the die that is induced by the die attach. The bond wire attachment is compared with conventional single-sided die attach using two types of commercially available adhesives. It was found that the proposed packaging system exhibits multiple resonance modes and displays a dependence on the amount of bond wires. White-light interferometry reveals a centered bow across the die and shows low-induced stresses compared with conventionally attached dies using epoxy adhesives.
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| 50. |
- Somjit, Nutapong, et al.
(författare)
-
Deep-Reactive-Ion-Etched Wafer-Scale-Transferred All-Silicon Dielectric-Block Millimeter-Wave MEMS Phase Shifters
- 2010
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Ingår i: Journal of microelectromechanical systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1057-7157 .- 1941-0158. ; 19:1, s. 120-128
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports on design, fabrication, and characterization of a novel multistage all-silicon microwave MEMS phase-shifter concept, based on multiple-step deep-reactive-ion-etched monocrystalline-silicon dielectric blocks which are transfer bonded to an RF substrate containing a 3-D micromachined coplanar waveguide. The relative phase shift of 45 degrees of a single stage is achieved by vertically moving the lambda/2-long blocks by MEMS electrostatic actuation. The measurement results of the first prototypes show that the return and insertion loss of a 7 x 45 degrees multistage phase shifter over the whole frequency spectrum from 1 to 110 GHz are better than -12 and -5.1 dB, respectively. The monocrystalline high-resistivity silicon blocks are acting as a dielectric material from an RF point of view, and at the same time as actuation electrodes for dc electrostatic actuation. The mechanical reliability was investigated by measuring life-time cycles. All tested phase shifters with three-meander 36.67-N/m mechanical spring and a pull-in voltage of 29.9 V survived 1 billion cycles after which the tests were discontinued, no indication of dielectric charging could be found, neither caused by the dielectric block nor by the Si3N4 distance keepers to the bottom electrodes. Finally, it is investigated that, by varying the fill factor of the etch hole pattern, the effective dielectric constant of the block can be tailor made, resulting in 45 degrees, 30 degrees, and 15 degrees phase-shifter stages fabricated out of the same dielectric material by the same fabrication process flow. [2009-0201]
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