| 1. |
- Berglund, Martin, 1985-, et al.
(författare)
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Dynamic characterization and modelling of a dual-axis beam steering device for performance understanding, optimization, and control design
- 2013
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 23:4, s. 045020-
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a lumped thermal model of a dual-axis laser micromirror device for beam steering in a free-space optical (FSO) communication system, designed for fractionated spacecraft. An FSO communication system provides several advantages, such as larger bandwidth, smaller size and weight of the communication payload and less power consumption. A dual-axis mirror device is designed and realized using microelectromechanical systems technology. The fabrication is based on a double-sided, bulk micromachining process, where the mirror actuates thermally by joints consisting of v-grooves filled with the SU-8 polymer. The size of the device, consisting of a mirror, which is deflectable versus its frame in one direction, and through deflection of the frame in the other, is 15.4 × 10.4 × 0.3 mm3. In order to further characterize and understand the micromirror device, a Simulink state-space model of the actuator is set up using thermal and mechanical properties from a realized actuator. A deviation of less than 2% between the modelled and measured devices was obtained in an actuating temperature range of 20–200 °C. The model of the physical device was examined by evaluating its performance in vacuum, and by changing physical parameters, such as thickness and material composition. By this, design parameters were evaluated for performance gain and usability. For example, the crosstalk between the two actuators deflecting the mirror along its two axes in atmospheric pressure is projected to go down from 97% to 6% when changing the frame material from silicon to silicon dioxide. A feedback control system was also designed around the model in order to examine the possibility to make a robust control system for the physical device. In conclusion, the model of the actuator presented in this paper can be used for further understanding and development of the actuator system.
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| 2. |
- Sinno, Ihab, 1982, et al.
(författare)
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Fabrication of nanoscale electrostatic lenses
- 2010
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Ingår i: Journal of Micromechanics and Microengineering. - Philadelphia : IOP Publishing. - 1361-6439 .- 0960-1317. ; 20:9
-
Tidskriftsartikel (refereegranskat)abstract
- The fabrication of cylindrical multi-element electrostatic lenses at the nanoscale presents a challenge; they are high-aspect-ratio structures that should be rotationally symmetric, well aligned and freestanding, with smooth edges and flat, clean surfaces. In this paper, we present the fabrication results of a non-conventional process, which uses a combination of focused gallium ion-beam milling and hydrofluoric acid vapor etching. This process makes it possible to fabricate nanoscale electrostatic lenses down to 140 nm in aperture diameter and 4.2 mu m in column length, with a superior control of the geometry as compared to conventional lithography-based techniques.
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| 3. |
- Morikawa, Kyojiro, et al.
(författare)
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Fused silica microchannel fabrication with smooth surface and high etching selectivity
- 2023
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 33:4
-
Tidskriftsartikel (refereegranskat)abstract
- Channel fabrication technology has become increasingly important for microfluidic and nanofluidic devices. In particular, glass channels have high chemical and physical stability, high optical transparency, and ease of surface modification, so that there is increasing interest in glass microfluidic devices for chemical experiments in microfluidics and nanofluidics. For the fabrication of glass channels, especially those with a high aspect ratio (depth/width), lithography using a metal resist and dry etching have mainly been used. However, there are still issues involving the surface roughness of the etched channel and the low etching selectivity. In this study, a microchannel fabrication method with high etching selectivity that produces a smooth etched surface was developed. First, interference during dry etching by remaining Cr particles after the photolithography and Cr etching processes was assumed as the cause of the rough etched surface. Three different dry etching processes were introduced to verify this. In process 1 without removal of the Cr particles, the etched surface was not flat and had a 1 μm scale roughness. In process 2 where a cleaning process was included and high power etching was conducted, a smooth surface with a 1 nm scale roughness and a faster etching rate of 0.3 μm min−1 were obtained. For this high-power etching condition, the etching selectivity (fused silica/Cr) was relatively low at approximately 39-43. In process 3 with a cleaning process and low-power etching, although the etching rate was relatively low at 0.1 μm min−1, a smooth surface with 1 nm scale roughness (10 nm scale roughness deeper than 40 μm in the depth region) and a much higher etching selectivity of approximately 79-84 were obtained. The dry etching method presented in this study represents a significant contribution to microfluidics/nanofluidics for microchannel/nanochannel fabrication.
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| 4. |
- Ohlin, Mathias, et al.
(författare)
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Improved positioning and detectability of microparticles in droplet microfluidics using two-dimensional acoustophoresis
- 2017
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 27:8
-
Tidskriftsartikel (refereegranskat)abstract
- We have fabricated a silicon-glass two-phase droplet microfluidic system capable of generating sub 100 μm-sized, ø = (74 ± 2) μm, spherical droplets at rates of up to hundreds of hertz. By implementing a two-dimensional (2D) acoustophoresis particle-positioning method, we show a fourfold improvement in both vertical and lateral particle positioning inside the droplets compared to unactuated operation. The efficiency of the system has been optimized by incorporating aluminum matching layers in the transducer design permitting biocompatible operational temperatures (<37 °C). Furthermore, by using acoustic actuation, (99.8 ± 0.4)% of all encapsulated microparticles can be detected compared to only (79.0 ± 5.1)% for unactuated operation. In our experiments we observed a strong ordering of the microparticles in distinct patterns within the droplet when using 2D acoustophoresis; to explain the origin of these patterns we simulated numerically the fluid flow inside the droplets and compared with the experimental findings.
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| 5. |
- Åkerfeldt, Erika, et al.
(författare)
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Systematic variation of design aspects for a significant increase in thermal fracture resistance of alumina microthrusters
- 2021
-
Ingår i: Journal of Micromechanics and Microengineering. - : Institute of Physics Publishing (IOPP). - 0960-1317 .- 1361-6439. ; 31:8
-
Tidskriftsartikel (refereegranskat)abstract
- Because of thermal stresses occurring upon rapid heating or cooling, microcomponents made from high-temperature co-fired ceramics (HTCC) often fail at temperatures far below what the materials can withstand per se. This work investigates how resistance to thermal fracture in HTCC microcomponents can be increased by improving the component design, aiming at increasing the thermal performance of a microthruster with integrated heaters. The effect of four design parameters: component and cavity geometries (circular or square), heater location (central or peripheral), and addition of embedded platinum layers, on thermal fracture resistance was investigated through a full factorial designed experiment. Components of different designs were manufactured, and their thermal fracture resistance tested by rapid heating until failure. Peripheral heater location and presence of embedded platinum layers were seen to improve resistance to thermal fracture, whereas the shape of the component and the cavity did not significantly affect thermal performance. The most favourable design was then used for a cold gas microthruster that was fabricated and evaluated with respect to thermal fracture resistance. The microthruster survived rapid heating up to 1460 °C and was operated as a cold gas thruster at temperatures up to 772 °C, which is more than twice the maximum temperatures previously reported for alumina microthrusters.
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| 6. |
- Forsberg, Fredrik, et al.
(författare)
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A Comparative study of the bonding energy in adhesive wafer bonding
- 2013
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 23:8, s. 1-7
-
Tidskriftsartikel (refereegranskat)abstract
- Adhesion energies are determined for three different polymers currently used in adhesive wafer bonding of silicon wafers. The adhesion energies of the polymer off-stoichiometry thiol-ene-epoxy OSTE+ and the nano-imprint resist mr-I 9150XP are determined. The results are compared to the adhesion energies of wafers bonded with benzocyclobutene, both with and without adhesion promoter. The adhesion energies of the bonds are studied by blister tests, consisting of delaminating silicon lids bonded to silicon dies with etched circular cavities, using compressed nitrogen gas. The critical pressure needed for delamination is converted into an estimate of the bond adhesion energy. The fabrication of test dies and the evaluation method are described in detail. The mean bond energies of OSTE+ were determined to be 2.1 and 20 J m(-2) depending on the choice of the epoxy used. A mean bond energy of 1.5 J m(-2) was measured for mr-I 9150XP.
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| 7. |
- Yantchev, Ventsislav, et al.
(författare)
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Thin film lamb wave resonators in frequency control and sensing applications : a review
- 2013
-
Ingår i: Journal of Micromechanics and Microengineering. - : Institute of Physics (IOP). - 0960-1317 .- 1361-6439. ; 23:4, s. 043001-
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Tidskriftsartikel (refereegranskat)abstract
- This work makes an overview of the progress made during the last decade with regard to a novel class of piezoelectric microwave devices employing acoustic Lamb waves in micromachined thin film membranes. This class of devices is referred to as either thin film Lamb wave resonators or piezoelectric contour-mode resonators both employing thin film aluminum nitride membranes. These devices are of interest for applications in both frequency control and sensing. High quality factor Lamb wave resonators exhibiting low noise, low loss and thermally stable performance are demonstrated and their application in high resolution gravimetric and pressure sensors further discussed. A specific emphasis is put on the ability of these devices to operate in contact with liquids. Future research directions are further outlined.
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| 8. |
- Arapan, Lilia, 1974-, et al.
(författare)
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An intermode-coupled thin-film micro-acoustic resonator
- 2012
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 22:8, s. 085004-
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Tidskriftsartikel (refereegranskat)abstract
- A novel concept for the development of thin-film micro-acoustic resonators based on the coupling between different plate acoustic modes was demonstrated. The basic principles for the design and fabrication of intermode-coupled plate acoustic wave resonators on c-textured thin AlN films were presented and first experimental proof of coupling between laterally propagating waves and BAW was demonstrated. The experimental results demonstrate that the grating-assisted intermode coupling can be employed in high-frequency resonators inheriting the low dispersive nature of the S0 mode in combination with the energy localization in the plate bulk typical for the fundamental thickness shear resonance.
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| 9. |
- Fischer, Andreas C., 1982-, et al.
(författare)
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Unconventional applications of wire bonding create opportunities for microsystem integration
- 2013
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP publishing. - 0960-1317 .- 1361-6439. ; 23:8, s. 083001-
-
Forskningsöversikt (refereegranskat)abstract
- Automatic wire bonding is a highly mature, cost-efficient and broadly available back-endprocess, intended to create electrical interconnections in semiconductor chip packaging. Modern production wire-bonding tools can bond wires with speeds of up to 30 bonds per second with placement accuracies of better than 2 mu m, and the ability to form each wire individually into a desired shape. These features render wire bonding a versatile tool also for integrating wires in applications other than electrical interconnections. Wire bonding has been adapted and used to implement a variety of innovative microstructures. This paper reviews unconventional uses and applications of wire bonding that have been reported in the literature. The used wire-bonding techniques and materials are discussed, and the implemented applications are presented. They include the realization and integration of coils, transformers, inductors, antennas, electrodes, through silicon vias, plugs, liquid and vacuum seals, plastic fibers, shape memory alloy actuators, energy harvesters and sensors.
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| 10. |
- Fischer, Andreas C., 1982-, et al.
(författare)
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Very high aspect ratio through-silicon vias (TSVs) fabricated using automated magnetic assembly of nickel wires
- 2012
-
Ingår i: Journal of Micromechanics and Microengineering. - : Institute of Physics (IOP). - 0960-1317 .- 1361-6439. ; 22:10, s. 105001-
-
Tidskriftsartikel (refereegranskat)abstract
- Through-silicon via (TSV) technology enables 3D-integrated devices with higher performance and lower cost as compared to 2D-integrated systems. This is mainly due to smaller dimensions of the package and shorter internal signal lengths with lower capacitive, resistive and inductive parasitics. This paper presents a novel low-cost fabrication technique for metal-filled TSVs with very high aspect ratios (>20). Nickel wires are placed in via holes of a silicon wafer by an automated magnetic assembly process and are used as a conductive path of the TSV. This metal filling technique enables the reliable fabrication of through-wafer vias with very high aspect ratios and potentially eliminates characteristic cost drivers in the TSV production such as advanced metallization processes, wafer thinning and general issues associated with thin-wafer handling.
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| 11. |
- Fischer, Andreas C., 1982-, et al.
(författare)
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Wire-bonded through-silicon vias with low capacitive substrate coupling
- 2011
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Science. - 0960-1317 .- 1361-6439. ; 21:8, s. 085035-
-
Tidskriftsartikel (refereegranskat)abstract
- Three-dimensional integration of electronics and/or MEMS-based transducers is an emerging technology that vertically interconnects stacked dies with through-silicon vias (TSVs). They enable the realization of circuits with shorter signal path lengths, smaller packages and lower parasitic capacitances, which results in higher performance and lower costs. This paper presents a novel technique for fabricating TSVs from bonded gold wires. The wires are embedded in a polymer, which acts both as an electrical insulator, resulting in low capacitive coupling toward the substrate and as a buffer for thermo-mechanical stress.
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| 12. |
- Fischer, Andreas C., 1982-, et al.
(författare)
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Wire-bonder-assisted integration of non-bondable SMA wires into MEMS substrates
- 2012
-
Ingår i: Journal of Micromechanics and Microengineering. - : Institute of Physics Publishing (IOPP). - 0960-1317 .- 1361-6439. ; 22:5, s. 055025-
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports on a novel technique for the integration of NiTi shape memory alloy wires and other non-bondable wire materials into silicon-based microelectromechanical system structures using a standard wire-bonding tool. The efficient placement and alignment functions of the wire-bonding tool are used to mechanically attach the wire to deep-etched silicon anchoring and clamping structures. This approach enables a reliable and accurate integration of wire materials that cannot be wire bonded by traditional means.
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| 13. |
- Karlsson, J. Mikael, 1982-, et al.
(författare)
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Low-stress transfer bonding using floatation
- 2012
-
Ingår i: Journal of Micromechanics and Microengineering. - : Institute of Physics Publishing (IOPP). - 0960-1317 .- 1361-6439. ; 22:7, s. 075005-075011
-
Tidskriftsartikel (refereegranskat)abstract
- A novel method for transferring thin, large-area polymer layers from a mould and its subsequent bonding to a destination substrate is presented here. Buoyancy is used for transfer via floatation to allow the release of internal stress in the polymer and to avoid induced strain. Additionally, floatation leads to wrinkle-free contact between the polymer layer and its destination substrate, an important feature for the transfer of large-area polymer sheets. Poly(vinyl alcohol) is used as a release film on the mould, from which the device polymer layer is released using ultrasonication. The polymer layer floats from the mould to a destination surface, to which it automatically aligns. Here, the method is demonstrated by the successful manufacturing of a 4 '' sized, triple microfluidic layer PDMS stack on a silicon wafer, containing a total of 48 large-area, fragile membranes, each with a thickness of 50 mu m.
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| 14. |
- Roxhed, Niclas, et al.
(författare)
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A Compact, Low-cost Microliter-range Liquid Dispenser based on Expandable Microspheres
- 2006
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 16:12, s. 2740-2746
-
Tidskriftsartikel (refereegranskat)abstract
- This work presents a new low-cost liquid dispenser for the dispensing of microliters to milliliter volumes. The dispensing mechanism is based on a thermal actuator where highly expandable microspheres expand into a liquid reservoir consequently displacing any stored liquid. All device components are made out of low-cost materials and the fabrication process has the potential for high volume batch manufacturing. The device utilizes the property of the expandable microspheres to form a heat insulating layer between the heat source and the delivered liquid. Moreover, it does not require any feed back or complicated flow metering. The device was successfully tested showing a mean dispensed volume of 101 mu 1 with a standard deviation of 3.2% and with a maximum temperature of 59 degrees C in the liquid during actuation. It was shown that the dispenser is strong enough to deliver against counter pressures as high as 75 kPa. The device can also function as a low flow rate dispenser as demonstrated in a microfluidic dye laser application. The flow rate can be controlled between 1 mu 1 h(-1) and 2400 mu 1 h(-1) by adjusting the actuation power.
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| 15. |
- Sandström, Niklas, 1981-, et al.
(författare)
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Reaction injection molding and direct covalent bonding of OSTE+ polymer microfluidic devices
- 2015
-
Ingår i: Journal of Micromechanics and Microengineering. - : Institute of Physics (IOP). - 0960-1317 .- 1361-6439. ; 25:7
-
Tidskriftsartikel (refereegranskat)abstract
- In this article, we present OSTE+RIM, a novel reaction injection molding (RIM) process that combines the merits of off-stoichiometric thiol–ene epoxy (OSTE+) thermosetting polymers with the fabrication of high quality microstructured parts. The process relies on the dual polymerization reactions of OSTE+ polymers, where the first curing step is used in OSTE+RIM for molding intermediately polymerized parts with well-defined shapes and reactive surface chemistries. In the facile back-end processing, the replicated parts are directly and covalently bonded and become fully polymerized using the second curing step, generating complete microfluidic devices. To achieve unprecedented rapid processing, high replication fidelity and low residual stress, OSTE+RIM uniquely incorporates temperature stabilization and shrinkage compensation of the OSTE+ polymerization during molding. Two different OSTE+ formulations were characterized and used for the OSTE+RIM fabrication of optically transparent, warp-free and natively hydrophilic microscopy glass slide format microfluidic demonstrator devices, featuring a storage modulus of 2.3 GPa and tolerating pressures of at least 4 bars.
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| 16. |
- Thorslund, Sara, et al.
(författare)
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A disposable and multifunctional capsule for easy operation of microfluidic elastomer systems
- 2011
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Ingår i: Journal of Micromechanics and Microengineering. - : Institute of Physics (IOP). - 0960-1317 .- 1361-6439. ; 21:12, s. 127001-
-
Tidskriftsartikel (refereegranskat)abstract
- The global lab-on-chip and microfluidic markets for cell-based assays have been predicted to grow considerably, as novel microfluidic systems enable cell biologists to perform in vitro experiments at an unprecedented level of experimental control. Nevertheless, microfluidic assays must, in order to compete with conventional assays, be made available at easily affordable costs, and in addition be made simple to operate for users having no previous experience with microfluidics. We have to this end developed a multifunctional microfluidic capsule that can be mass-produced at low cost in thermoplastic material. The capsule enables straightforward operation of elastomer inserts of optional design, here exemplified with insert designs for molecular gradient formation in microfluidic cell culture systems. The integrated macro–micro interface of the capsule ensures reliable connection of the elastomer fluidic structures to an external perfusion system. A separate compartment in the capsule filled with superabsorbent material is used for internal waste absorption. The capsule assembly process is made easy by integrated snap-fits, and samples within the closed capsule can be analyzed using both inverted and upright microscopes. Taken together, the capsule concept presented here could help accelerate the use of microfluidic-based biological assays in the life science sector.
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| 17. |
- Williams, Kirk, et al.
(författare)
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Electrothermal feasibility of carbon microcoil heaters for cold/hot gas microthrusters
- 2006
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 16, s. 1154-1161
-
Tidskriftsartikel (refereegranskat)abstract
- With the miniaturization of spacecraft the need for efficient, accurate and low-weight attitude control systems is becoming evident. To this end, the cold/hot gas microthruster system of this paper incorporates carbon microcoils—deposited via laser-induced chemical vapor deposition—for heating the propellant gas (nitrogen) before the nozzle inlet. By increasing the temperature of the propellant gas for such a system, the specific impulse (Isp) of the microthruster will increase. The benefits of a higher Isp are lower propellant mass, higher thrust and shorter burning times. Therefore, the feasibility of achieving this increase with the carbon microcoils is investigated. The carbon microcoils have been characterized experimentally with respect to their electrothermal performance, i.e. resistance, temperature, parasitic heat losses and degradation in ambient. The resulting heat losses from the heater and the heated gas have been estimated through a combination of experiments, numerical simulation and approximate analytical expressions. At high powers, degradation of the carbon material leads to coil failure in ambient where trace oxygen was present. Thus, the next generation of carbon microcoils to be tested will have a protective coating to extend their lifetime. Theoretical modeling showed that an increase in the propellant gas temperature from 300 to 1200 K and a corresponding two-fold increase in the Isp can be achieved if 1.0 W of power is supplied to each coil in a three-coil thruster. These simulation results show that if the coils are capable of dissipating 1 W of heat at 1700 K coil temperature, the doubling of the Isp may be achieved. Comparing to the electrothermal characterization results we find that the carbon coils can survive at 1700 K if protected, and that they can be expected to reach 1700 K at power below 1 W.
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| 18. |
- Edqvist, Erik, et al.
(författare)
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Evaluation of building technology for mass producible millimetre-sized robots using flexible printed circuit boards
- 2009
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Ingår i: Journal of Micromechanics and Microengineering. - : Institute of Physics Publishing. - 0960-1317 .- 1361-6439. ; 19:7, s. 11pp-
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Tidskriftsartikel (refereegranskat)abstract
- Initial tests of a building technology for a compact three-dimensional mass produciblemicrorobot are presented. The 3.9 × 3.9 × 3.3 mm3 sized prototype robot represents amicrosystem with actuators, sensors, energy management and integrated electronics. Theweight of a folded robot is 65 mg and the total volume is less than 23 mm3. The design of theinterfaces of the different modules in the robot, as well as the building technology, isdescribed. The modules are assembled using conductive adhesive with industrial surfacemounting technology on a thin double-sided flexible printed circuit board. The final shape ofthe microrobots is achieved by folding the flexible printed circuit board twice. Electrical andmechanical studies are performed to evaluate the assembly and it is concluded that thetechnology can be used for this type of microsystem. Several issues using the presentedassembly technique are identified and addressed.
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| 19. |
- Evander, Mikael, et al.
(författare)
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Microfluidic PMMA interfaces for rectangular glass capillaries
- 2014
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Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 24:2
-
Tidskriftsartikel (refereegranskat)abstract
- We present the design and fabrication of a polymeric capillary fluidic interface fabricated by micro-milling. The design enables the use of glass capillaries with any kind of cross-section in complex microfluidic setups. We demonstrate two different designs of the interface; a double-inlet interface for hydrodynamic focusing and a capillary interface with integrated pneumatic valves. Both capillary interfaces are presented together with examples of practical applications. This communication shows the design optimization and presents details of the fabrication process. The capillary interface opens up for the use of complex microfluidic systems in single-use glass capillaries. They also enable simple fabrication of glass/polymer hybrid devices that can be beneficial in many research fields where a pure polymer chip negatively affects the device's performance, e.g. acoustofluidics.
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| 20. |
- Fu, Yifeng, 1984, et al.
(författare)
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Application of through silicon via technology for in situ temperature monitoring on thermal interfaces
- 2010
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Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 1361-6439 .- 0960-1317. ; 20:2, s. id 025027 (5 pp)-
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a series of micro-machining processes have been developed to fabricate a test platform with the ability of in situ temperature monitoring on thermal interface behaviour. Through silicon vias (TSVs) with an aspect ratio up to 13 using Cu as a conductor have been applied to connect an array of platinum-based temperature sensors directly deposited on the thermal interfaces to be measured. The sensors are subsequently calibrated by an industry standard resistance temperature detector. Results show that the temperature sensors function normally in a temperature range up to 250 degrees C. This demonstrates the successful deposition of temperature-sensing materials and their good connection to the TSVs. The realization of direct precise temperature measurement on the thermal interface of this test platform enables thermal characterization with a high accuracy.
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| 21. |
- Ghaderi, M., et al.
(författare)
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Design, fabrication and characterization of infrared LVOFs for measuring gas composition
- 2014
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 1361-6439 .- 0960-1317. ; 24:8, s. Art. no. 084001-
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the design, fabrication and characterization of a linear-variable optical-filter (LVOF) that will be used in a micro-spectrometer operating in infrared (IR) for natural gas composition measurement. An LVOF is placed on top of an array of detectors and transforms the optical spectrum into a lateral intensity profile, which is recorded by the detectors. The IR LVOF was fabricated in an IC-compatible process using a photoresist reflow technique, followed by transfer etching of the photoresist into the optical resonator layer. The spectral range between 3 to 5 mu m contains the absorption peaks for hydrocarbons, carbon-monoxide and carbon-dioxide. The resulting optical absorption is utilized to measure the gas concentrations in a sample volume. Two LVOF structures were designed and fabricated on silicon wafers using alternate layers of sputtered silicon and silicon-dioxide as the high- and low- refractive index materials. These filters consist of a Fabry-Perot resonator combined with a band-pass filter designed to block out-of-band transmissions. Finally, the filters were fully characterized with an FTIR spectrometer and showed satisfactory agreement with the optical thin-film simulations. The characterization showed a spectral resolution of 100 nm, which can be further improved with signal processing algorithms. This method makes it possible to fabricate small and robust LVOFs with high resolving power in the IR spectral range directly on the detector array chip.
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| 22. |
- Gradin, Henrik, et al.
(författare)
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Localized removal of the Au-Si eutectic bonding layer for the selective release of microstructures
- 2009
-
Ingår i: Journal of Micromechanics and Microengineering. - : Institute of Physics (IOP). - 0960-1317 .- 1361-6439. ; 19:10, s. 105014-105023
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents and investigates a novel technique for the footprint and thickness-independent selective release of Au–Si eutectically bonded microstructures through the localized removal of their eutectic bond interface. The technique is based on the electrochemical removal of the gold in the eutectic layer and the selectivity is provided by patterning the eutectic layer and by proper electrical connection or isolation of the areas to be etched or removed, respectively. The gold removal results in a porous silicon layer, acting similar to standard etch holes in a subsequent sacrificial release etching. The paper presents the principle and the design requirements of the technique. First test devices were fabricated and the method successfully demonstrated. Furthermore, the paper investigates the release mechanism and the effects of different gold layouts on both the eutectic bonding and the release procedure.
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| 23. |
- Khan, Mohammed Faheem, et al.
(författare)
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Methods for characterization of wafer-level encapsulation applied on Si to LTCC Anodic bonding
- 2010
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 20:6
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents initial results on generic characterization methods for wafer-level encapsulation. The methods, developed specifically to evaluate anodic bonding of low-temperature cofired ceramics (LTCC) to Si, are generally applicable to wafer-level encapsulation. Different microelectromechanical system (MEMS) structures positioned over the whole wafer provide local information about the bond quality. The structures include (i) resonating cantilevers as pressure sensors for bond hermeticity, (ii) resonating bridges as stress sensors for measuring the stress induced by the bonding and (iii) frames/mesas for pull tests. These MEMS structures have been designed, fabricated and characterized indicating that local information can easily be obtained. Buried electrodes to enable localized bonding have been implemented and their effectiveness is indicated from first results of the novel Si to LTCC anodic bonding.
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| 24. |
- Manneberg, Otto, et al.
(författare)
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Wedge transducer design for two-dimensional ultrasonic manipulation in a microfluidic chip
- 2008
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Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 18, s. 095025-
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Tidskriftsartikel (refereegranskat)abstract
- We analyze and optimize the design of wedge transducers used for the excitation of resonances in the channel of a microfluidic chip in order to efficiently manipulate particles or cells in more than one dimension. The design procedure is based on (1) theoretical modeling of acoustic resonances in the transducer-chip system and calculation of the force fields in the fluid channel, (2) full-system resonance characterization by impedance spectroscopy and (3) image analysis of the particle distribution after ultrasonic manipulation. We optimize the transducer design in terms of actuation frequency, wedge angle and placement on top of the chip, and we characterize and compare the coupling effects in orthogonal directions between single- and dual-frequency ultrasonic actuation. The design results are verified by demonstrating arraying and alignment of particles in two dimensions. Since the device is compatible with high-resolution optical microscopy, the target application is dynamic cell characterization combined with improved microfluidic sample transport.
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| 25. |
- Rahiminejad, Sofia, 1987, et al.
(författare)
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A four level silicon microstructure fabrication by DRIE
- 2016
-
Ingår i: Journal of Microelectromechanical Systems. - : IOP Publishing. - 1057-7157. ; 26:8
-
Tidskriftsartikel (refereegranskat)abstract
- We present a four level Si microstructure fabrication process with depths ranging from 70-400 μm. All four levels are etched from the same side, by using four hard masks (SiO2, Al, AZ4562 photo resist, and Al). The choice of the hard masks and their relative selectivity will be discussed. Also two different deep reactive ion etching (DRIE) processes, performed in two different machines, are compared and evaluated. The process evaluation and discussions are based on the vertical walls deviation from a right angle, the surface roughness and the resolution. In the end, a solution is proposed to remove spikes and grassing which appeared during both DRIE processes, and the impact of removing them from the surfaces is discussed.
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| 26. |
- Rahiminejad, Sofia, 1987, et al.
(författare)
-
Demonstration of a micromachined planar distribution network in gap waveguide technology for a linear slot array antenna at 100 GHz
- 2016
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 1361-6439 .- 0960-1317. ; 26:7, s. Art. no. 074001-
-
Tidskriftsartikel (refereegranskat)abstract
- The need for high frequency antennas is rapidly increasing with the development of new wireless rate communication technology. Planar antennas have an attractive form factor, but they require a distribution network. Microstrip technology is most commonly used at low frequency but suffers from large dielectric and ohmic losses at higher frequencies and particularly above 100 GHz. Substrate-integrated waveguides also suffer from dielectric losses. In addition, standard rectangular waveguide interfaces are inconvenient due to the four flange screws that must be tightly fastened to the antenna to avoid leakage. The current paper presents a planar slot array antenna that does not suffer from any of these problems. The distribution network is realized by micromachining using low-loss gap waveguide technology, and it can be connected to a standard rectangular waveguide flange without using any screws or additional packaging. To realize the antenna at these frequencies, it was fabricated with micromachining, which offers the required high precision, and a low-cost fabrication method. The antenna was micromachined with DRIE in two parts, one silicon-on-insulator plate and one Si plate, which were both covered with Au to achieve conductivity. The input reflection coefficient was measured to be below 10 dB over a 15.5% bandwidth, and the antenna gain was measured to be 10.4 dBi, both of which are in agreement with simulations.
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| 27. |
- Saharil, Farizah, et al.
(författare)
-
Dry adhesive bonding of nanoporous inorganic membranes to microfluidic devices using the OSTE(+) dual-cure polymer
- 2013
-
Ingår i: Journal of Micromechanics and Microengineering. - : Institute of Physics Publishing (IOPP). - 0960-1317 .- 1361-6439. ; 23:2, s. 025021-
-
Tidskriftsartikel (refereegranskat)abstract
- We present two transfer bonding schemes for incorporating fragile nanoporous inorganic membranes into microdevices. Such membranes are finding increasing use in microfluidics, due to their precisely controllable nanostructure. Both schemes rely on a novel dual-cure dry adhesive bonding method, enabled by a new polymer formulation: OSTE(+), which can form bonds at room temperature. OSTE(+) is a novel dual-cure ternary monomer system containing epoxy. After the first cure, the OSTE(+) is soft and suitable for bonding, while during the second cure it stiffens and obtains a Young's modulus of 1.2 GPa. The ability of the epoxy to react with almost any dry surface provides a very versatile fabrication method. We demonstrate the transfer bonding of porous silicon and porous alumina membranes to polymeric microfluidic chips molded into OSTE(+), and of porous alumina membranes to microstructured silicon wafers, by using the OSTE(+) as a thin bonding layer. We discuss the OSTE(+) dual-cure mechanism, describe the device fabrication and evaluate the bond strength and membrane flow properties after bonding. The membranes bonded to OSTE(+) chips delaminate at 520 kPa, and the membranes bonded to silicon delaminate at 750 kPa, well above typical maximum pressures applied to microfluidic circuits. Furthermore, no change in the membrane flow resistance was observed after bonding.
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| 28. |
- Samel, Björn, et al.
(författare)
-
The fabrication of microfluidic structures by means of full-wafer adhesive bonding using a poly(dimethylsiloxane) catalyst
- 2007
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 17:8, s. 1710-1714
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, we present the use of a PDMS ( poly( dimethylsiloxane)) curing-agent as the intermediate layer for adhesive full-wafer bonding suitable for fabrication of microfluidic structures. The curing-agent of the two-component silicone rubber (Sylgard 184) is spin coated on a substrate, brought into contact with another PDMS layer and heat cured to create an irreversible seal which is as strong as or even stronger than plasma-assisted PDMS bonding. The maximum bond strength is measured to 800 kPa when bonding together PDMS and silicon. The applicability of the new PDMS adhesive bonding method is verified by means of fabricating microfluidic structures. Using this method allows for wafer-level bonding of PDMS to various materials such as PDMS, glass or silicon and more importantly to selectively bond different layers by using a patterned adhesive bonding technique. Moreover, precise alignment of the structural layers is facilitated since curing is initiated upon heat which is an advantage when fabricating multilayer microfluidic devices.
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| 29. |
- Svennebring, Jessica, et al.
(författare)
-
Temperature regulation during ultrasonic manipulation for long-term cell handling in a microfluidic chip
- 2007
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 17, s. 2469-2474
-
Tidskriftsartikel (refereegranskat)abstract
- Regulation by the use of ultrasonic standing wave technology in a microfluidic chip. The system is based on a microfabricated silicon structure sandwiched between two glass layers, and an external ultrasonic transducer using a refractive wedge placed on top of the chip for efficient coupling of ultrasound into the microchannel. The chip is fully transparent and compatible with any kind of high-resolution optical microscopy. The temperature regulation method uses calibration data of the temperature increase due to the ultrasonic actuation for determining the temperature of the surrounding air and microscope table, controlled by a warm-air heating unit and a heatable mounting frame. The heating methods are independent of each other, resulting in a flexible choice of ultrasonic actuation voltage and flow rate for different cell and particle manipulation purposes. Our results indicate that it is possible to perform stable temperature regulation with an accuracy of the order of +/- 0.1 degrees C around any physiologically relevant temperature (e.g., 37 degrees C) with high temporal stability and repeatability. The purpose is to use ultrasound for long-term cell and/or particle handling in a microfluidic chip while controlling and maintaining the biocompatibility of the system.
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| 30. |
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| 31. |
- Gradin, Henrik, et al.
(författare)
-
A low-power high-flow shape memory alloy wire gas microvalve
- 2012
-
Ingår i: Journal of Micromechanics and Microengineering. - : Institute of Physics (IOP). - 0960-1317 .- 1361-6439. ; 22:7, s. 1-10
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper the use of shape memory alloy (SMA) wire actuators for high gas flow control is investigated. A theoretical model for effective gas flow control is presented and gate microvalve prototypes are fabricated. The SMA wire actuator demonstrates the robust flow control of more than 1600 sccm at a pressure drop of 200 kPa. The valve can be successfully switched at over 10 Hz and at an actuation power of 90 mW. Compared to the current state-of-the-art high-flow microvalves, the proposed solution benefits from a low-voltage actuator with low overall power consumption. This paper demonstrate that SMA wire actuators are well suited for high-pressurehigh-flow applications.
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| 32. |
- Kolari, K., et al.
(författare)
-
Flow restrictor silicon membrane microvalve actuated by optically controlled paraffin phase transition
- 2014
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 24:8, s. 084003-
-
Tidskriftsartikel (refereegranskat)abstract
- Restrictor valves allow proportional control of fluid flow but are rarely integrated in microfluidic systems. In this study, an optically actuated silicon membrane restrictor microvalve is demonstrated. Its actuation is based on the phase transition of paraffin, using a paraffin wax mixed with a suitable concentration of optically absorbing nanographite particles. Backing up the membrane with oil (the melted paraffin) allows for a compliant yet strong contact to the valve seat, which enables handling of high pressures. At flow rates up to 30 mu L min(-1) and at a pressure of 2 bars, the valve can successfully be closed and control the flow level by restriction. The use of this paraffin composite as an adhesive layer sandwiched between the silicon valve and glass eases fabrication. This type of restrictor valve is best suited for high pressure, low volume flow silicon-based nanofluidic systems.
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| 33. |
- An, Hongbin, et al.
(författare)
-
A method of manufacturing microfluidic contact lenses by using irreversible bonding and thermoforming
- 2018
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP PUBLISHING LTD. - 0960-1317 .- 1361-6439. ; 28:10
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present the development of microfluidic contact lenses, which is based on the advantages of wearable microfluidics and can have great potential in the ophthalmology healthcare field. The development consists of two parts; the manufacturing process and the usability tests of the devices. In the manufacturing process, we firstly extended silane coupling and surface modification to irreversibly bond plastic membranes with microchannel-molded silicone rubber, to form the plastic-PDMS plane assemblies, and then molded the plane into a contact lens by thermoforming. We systematically investigated the effects of thermoforming factors, heating temperatures and the terrace die's sphere radius on channels by using the factorial experiment design. In addition, various tests were conducted to verify the usability of the devices. Through blockage and leakage tests, the devices were proved to be feasible, with no channel-blockages and could stand high pressures. Through a wearing test, the contact lenses were confirmed to be harmless on the living body. Furthermore, by performing the manipulating test, the device was proved to be liquid-controllable. These works provide a foundation for the applications of microfluidic contact lenses in ophthalmology.
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| 34. |
- Cruz, Javier, 1990-, et al.
(författare)
-
High pressure inertial focusing for separating and concentrating bacteria at high throughput
- 2017
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP PUBLISHING LTD. - 0960-1317 .- 1361-6439. ; 27:8
-
Tidskriftsartikel (refereegranskat)abstract
- Inertial focusing is a promising microfluidic technology for concentration and separation of particles by size. However, there is a strong correlation of increased pressure with decreased particle size. Theory and experimental results for larger particles were used to scale down the phenomenon and find the conditions that focus 1 mu m particles. High pressure experiments in robust glass chips were used to demonstrate the alignment. We show how the technique works for 1 mu m spherical polystyrene particles and for Escherichia coli, not being harmful for the bacteria at 50 mu l min(-1). The potential to focus bacteria, simplicity of use and high throughput make this technology interesting for healthcare applications, where concentration and purification of a sample may be required as an initial step.
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| 35. |
- Cruz, Javier, 1990-, et al.
(författare)
-
Stable 3D Inertial Focusing by High Aspect Ratio Curved Microfluidics
- 2021
-
Ingår i: Journal of Micromechanics and Microengineering. - : Institute of Physics Publishing (IOPP). - 0960-1317 .- 1361-6439. ; 31
-
Tidskriftsartikel (refereegranskat)abstract
- Fine manipulation of particles is essential for the analysis of complex samples such as blood or environmental water, where rare particles of interest may be masked by millions of others. Inertial focusing is amongst the most promising techniques for this task, enabling label-free manipulation of particles with sub-micron resolution at very high flow rates. However, the phenomenon still remains difficult to predict due to the focus position shifting in tortuous ways as function of the channel geometry, flow rate and particle size. Here, we present a new line of microfluidics that exploit inertial focusing in High Aspect Ratio Curved (HARC) microchannels and overcome this limitation. Consisting of a single curved channel, HARC systems provide a highly predictable, single focus position near the centre of the inner wall, largely independent of the flow rate and particle size.An explanation of the mechanism of migration and focus of particles, together with its governing equations, is provided based on simulations in COMSOL Multiphysics and experimental results. HARC microchannels built in silicon-glass were used for experimental validation, achieving a high quality, single focus position for a range of microparticles with sizes of 0.7 - 1 µm and bacterial cells (Escherichia coli). The recovery of 1 µm particles was 99.84% with a factor four in concentration.With a stable focus position, we envision that HARC systems will bring the technology closer to implementation in laboratories for analysis of complex fluids with biological particles like cells and organelles.
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| 36. |
- Karlsson, Anton, et al.
(författare)
-
Active real-time electric field control of the e-jet in near-field electrospinning using an auxiliary electrode
- 2021
-
Ingår i: Journal of Micromechanics and Microengineering. - : Institute of Physics Publishing (IOPP). - 0960-1317 .- 1361-6439. ; 31:3
-
Tidskriftsartikel (refereegranskat)abstract
- Near-field electrospinning (NFES) is an additive manufacturing technique that allows for both high-resolution 3D structures and a wide variety of printed materials. Typically, a high electric field between a nozzle, the spinneret, and the substrate creates a mu m-sized jet of a supplied liquid material. With mm distances between spinneret and sample, it is possible to have a fair control of the lateral placement of the deposited material. The placement is, however, distributed by various electrostatic phenomena, and this is one of the present challenges in developing NFES into a more versatile technique. In this paper, a higher degree of control in NFES placement was achieved through manipulation of the electric field direction, using an auxiliary steering electrode. The position of a polycaprolactone plastic jet was determined in real-time with a camera attached to a stereo microscope. The measured position was used to calculate an applied potential to the steering electrode to guide the plastic jet to the desired position. The placement accuracy was measured both at the substrate and during flight using the camera and microscope. The higher control was revealed through the deposition of plastic fibers in a pattern with decreasing separation, with and without the active steering electrode enabled. It is in the authors' opinion that the fabrication of dense structures could be possible with further refinement of the technique.
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| 37. |
- Khaji, Zahra, et al.
(författare)
-
Endurance and Failure of an Alumina-based Monopropellant Microthruster with Integrated Heater, Catalytic Bed and Temperature Sensors
- 2017
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 27:5, s. 1-11
-
Tidskriftsartikel (refereegranskat)abstract
- Monopropellant ceramic microthrusters with an integrated heater, catalytic bed and two temperature sensors, but of various designs, were manufactured by milling a fluidic channel and chamber, and a nozzle, and screen printing platinum patterns on green tapes of alumina that were stacked and laminated before sintering. In order to increase the surface area of the catalytic bed, the platinum paste was mixed with a sacrificial paste that disappeared during sintering, to leave behind a porous and rough layer. As an early development level in manufacturing robust and high-temperature tolerant microthrusters, the influence of design on the temperature gradients and dry temperature tolerance of the devices was studied. On average, the small reaction chambers showed a more than 1.5 times higher dry temperature tolerance (in centigrade) compared to devices with larger chambers, independent of the heater and device size. However, for a given temperature, big devices consumed on average 2.9 times more power than the small ones. It was also found that over the same area and under the same heating conditions, devices with small chambers were subjected to approximately 40% smaller temperature differences. A pressure test done on two small devices with small chambers revealed that pressures of at least 26.3 bar could be tolerated. Above this pressure, the interfaces failed but the devices were not damaged. To investigate the cooling effect of the micropropellant, the endurance of a full thruster was also studied under wet testing where it was fed with 31 wt.% hydrogen peroxide. The thruster demonstrated complete evaporation and/or full decomposition at a power above 3.7 W for a propellant flow of 50 mu l min(-1). At this power, the catalytic bed locally reached a temperature of 147 degrees C. The component was successfully heated to an operating temperature of 307 degrees C, where it cracked. Under these firing conditions, and assuming complete decomposition, calculations give a thrust and specific impulse of 0.96 mN and 106 s, respectively. In the case of evaporation, the corresponding values are calculated to be 0.84 mN and 92 s.
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| 38. |
- Khaji, Zahra, et al.
(författare)
-
Integrated cooling system for microfluidic PDMS devices used in biological microscopy studies
- 2022
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 32:8, s. 087001-
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, a two-channel, water-based cooling system was integrated into a PDMS-glass microfluidic device for application in single-cell biological studies. This system is designed to cool living cells to single-digit temperatures in situ, without requiring any features of the electron-beam fabricated master mould to be changed, and without interfering either biologically or optically with the cells themselves. The temperature profile inside the device was mapped using multiple thermocouples mounted inside the device, over time. A parametric study including coolant flow rate, distance between the cooling channel and the fluidic channel, and number of active cooling channels were performed to evaluate the performance of the system. By using ice water as the coolant, we have demonstrated stable on-chip cooling reaching an average temperature of 4.9 °C when operated at a coolant flow rate of 23 ml/min and using two active cooling channels, positioned only 400 μm away from the cell trapping sites. The maximum observed temperature deviation during an 80 min stability test was ± 0.2 °C. We have observed that flowing room temperature culture media through the device with active cooling had no influence on the temperature inside the chip, demonstrating its suitability for use in live cell culture experiments. Finally, we have also demonstrated that the active cooling system successfully decreased the cell metabolism of trapped E. coli resulting in a decreased growth rate of the bacteria.
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| 39. |
- Krause, Sascha, 1989, et al.
(författare)
-
Suspended GaN beams and membranes on Si as a platform for waveguide-based THz applications
- 2018
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 1361-6439 .- 0960-1317. ; 28:10
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the suitability of employing suspended GaN beams on a Pi-shaped Si frame for waveguide-based cryogenic THz components and systems. This concept addresses major challenges and provides eased device handling, cryogenic operation, micron-alignment possibilities, high integratability and allows the electrical contacting by using bonding wires. In particular, a balanced hot electron bolometer (HEB) mixer was implemented for frequencies at 1.3 THz with state-of-the-art IF performance, which combines micro-machined all-metal waveguide components in conjunction with a suspended GaN beam. In addition, in order to accomplish a proper design of active or passive components, the accurate knowledge of the effective dielectric constant at THz frequencies is crucial when such membranes are employed. Thus, a direct measurement method based on a resonance structure and an S-parameter measurement between 1 THz and 1.5 THz is also presented.
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| 40. |
- Kustanovich, Kiryl, 1987, et al.
(författare)
-
A high-performance lab-on-a-chip liquid sensor employing surface acoustic wave resonance
- 2017
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 1361-6439 .- 0960-1317. ; 27:11
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate herein a new concept for lab-on-a-chip in-liquid sensing, through integration of surface acoustic wave resonance (SAR) in a one-port configuration with a soft polymer microfluidic delivery system. In this concept, the reflective gratings of a one-port surface acoustic wave (SAW) resonator are employed as mass loading-sensing elements, while the SAW transducer is protected from the measurement environment. We describe the design, fabrication, implementation, and characterization using liquid medium. The sensor operates at a frequency of 185 MHz and has demonstrated a comparable sensitivity to other SAW in-liquid sensors, while offering quality factor (Q) value in water of about 250, low impedance and fairly low susceptibility to viscous damping. For proof of principle, sensing performance was evaluated by means of binding 40 nm neutravidin-coated SiO2 nanoparticles to a biotin-labeled lipid bilayer deposited over the reflectors. Frequency shifts were determined for every step of the affinity assay. Demonstration of this integrated technology highlights the potential of SAR technology for in-liquid sensing.
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| 41. |
- Kustanovich, Kiryl, 1987, et al.
(författare)
-
A high-performance lab-on-a-chip liquid sensor employing surface acoustic wave resonance: part II
- 2019
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 1361-6439 .- 0960-1317. ; 29:2
-
Tidskriftsartikel (refereegranskat)abstract
- We recently introduced an in-liquid sensing concept based on surface acoustic resonance (SAR) in a lab-on-a-chip resonant device with one electrical port. The 185 MHz one-port SAR sensor has a sensitivity comparable to other surface acoustic wave (SAW) in-liquid sensors, while offering a high quality factor (Q) in water, low impedance, and fairly low susceptibility to viscous damping. In this work, we present significant design and performance enhancements of the original sensor presented in part I. A novel 'lateral energy confinement' (LEC) design is introduced, where the spatially varying reflectivity of the SAW reflectors enables strong SAW localization inside the sensing domain at resonance. An improvement in mass-sensitivity greater than 100% at resonance is achieved, while the measurement noise stays below 0.5 ppm. Sensing performance was evaluated through real-time measurements of the binding of 40 nm neutravidin-coated SiO2nanoparticles to a biotin-labeled lipid bilayer. Two complementary sensing parameters are studied, the shift of resonance frequency and the shift of conductance magnitude at resonance.
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| 42. |
- Sandström, Niklas, et al.
(författare)
-
Batch fabrication of polymer microfluidic cartridges for QCM sensor packaging by direct bonding
- 2017
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 27:12
-
Tidskriftsartikel (refereegranskat)abstract
- Quartz crystal microbalance (QCM) sensing is an established technique commonly used in laboratory based life-science applications. However, the relatively complex, multi-part design and multi-step fabrication and assembly of state-of-the-art QCM cartridges makes them unsuited for disposable applications such as point-of-care (PoC) diagnostics. In this work, we present the uncomplicated manufacturing of QCMs in polymer microfluidic cartridges. Our novel approach comprises two key innovations: the batch reaction injection molding of microfluidic parts; and the integration of the cartridge components by direct, unassisted bonding. We demonstrate molding of batches of 12 off-stoichiometry thiol-ene epoxy polymer (OSTE+) polymer parts in a single molding cycle using an adapted reaction injection molding process; and the direct bonding of the OSTE+ parts to other OSTE+ substrates, to printed circuit boards, and to QCMs. The microfluidic QCM OSTE+ cartridges were successfully evaluated in terms of liquid sealing as well as electrical properties, and the sensor performance characteristics are on par with those of commercially available QCM biosensor cartridge.
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| 43. |
- Seton, Ragnar, 1985-, et al.
(författare)
-
PDMS-polyimide transcutaneous blood gas collector with self-folding out-of-plane heater elements
- 2023
-
Ingår i: Journal of Micromechanics and Microengineering. - : Institute of Physics Publishing (IOPP). - 0960-1317 .- 1361-6439. ; 33:6
-
Tidskriftsartikel (refereegranskat)abstract
- This paper introduces and evaluates a novel, highly scalable fabrication technique for folding flexible printed circuit board (PCB) features into polydimethylsiloxane (PDMS). The technique is then used to create fast and effective skin-heaters in a prototype gas collector for transcutaneous blood gas monitoring (TBM), a well-established technique to non-invasively measure the amount of CO2 and O2 in a patient's blood. Previous studies have shown that TBM can be made safer by heating the patient's skin with short pulses rather than continuously. Hence, the effects of incorporating a resistive heater with folded heating elements into a PDMS gas collector was investigated and compared to a heater with surface mounted heating elements. The results show that the fabrication technique provides consistent, controllable folding angles using only the surface and viscous forces of the flexible PCB and PDMS. With the investigated design- and material parameters a maximum folding angle of 30° was achieved, resulting in a 2000% increase in initial surface heating compared to an un-folded reference. For the intended application, this corresponds to reducing the time needed to heat the skin of a patient to less than half. The presented fabrication technique is, however, not limited to the application investigated in this paper, but rather offers the possibility to quickly and automatically fold complex structures and circuits into the bulk of the PDMS without introducing any time overhead as the number of features and folds grow.
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| 44. |
- Wang, Xiaojing, et al.
(författare)
-
Transfer printing of nanomaterials and microstructures using a wire bonder
- 2019
-
Ingår i: Journal of Micromechanics and Microengineering. - : Institute of Physics Publishing (IOPP). - 0960-1317 .- 1361-6439. ; 29:12
-
Tidskriftsartikel (refereegranskat)abstract
- Scalable and cost-efficient transfer of nanomaterials and microstructures from their original fabrication substrate to a new host substrate is a key challenge for realizing heterogeneously integrated functional systems, such as sensors, photonics, and electronics. Here we demonstrate a high-throughput and versatile integration method utilizing conventional wire bonding tools to transfer-print carbon nanotubes (CNTs) and silicon microstructures. Standard ball stitch wire bonding cycles were used as scalable and high-speed pick-and-place operations to realize the material transfer. Our experimental results demonstrated successful transfer printing of single-walled CNTs (100 μm-diameter patches) from their growth substrate to polydimethylsiloxane, parylene, or Au/parylene electrode substrates, and realization of field emission cathodes made of CNTs on a silicon substrate. Field emission measurements manifested excellent emission performance of the CNT electrodes. Further, we demonstrated the utility of a high-speed wire bonder for transfer printing of silicon microstructures (60 μm × 60 μm × 20 μm) from the original silicon on insulator substrate to a new host substrate. The achieved placement accuracy of the CNT patches and silicon microstructures on the target substrates were within ± 4 μm. These results show the potential of using established and extremely cost-efficient semiconductor wire bonding infrastructure for transfer printing of nanomaterials and microstructures to realize integrated microsystems and flexible electronics.
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| 45. |
- Werr, Gabriel, 1991-, et al.
(författare)
-
Integrated thin film resistive sensors for in situ temperature measurements in an acoustic trap
- 2019
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP PUBLISHING LTD. - 0960-1317 .- 1361-6439. ; 29:9, s. 140-141
-
Tidskriftsartikel (refereegranskat)abstract
- This work presents an acoustic trap with integrated thin film sensors to monitor temperature variations during operation. The acoustic trap is wet-etched in glass with a thermally bonded glass lid and the thin-film sensors are integrated during fabrication. We evaluated the performance of the integrated temperature sensors and measured a temperature sensitivity of +/- 0.01 degrees C and confirmed that the read-out of the thin film sensors was not affected neither by the ionic conductivity of the solution nor the addition of microparticles into the acoustic trap. From the experiments we observed a temperature increase of the acoustic trap during operation as a result of the dissipative heating of the the piezoelectric element used to actuate the trap. We also showed that when external convective cooling was applied to the system, the temperature increase of the acoustic trap was higher than the temperature increase of the piezoelectric element itself. This shows the importance of using integrated temperature sensors in acoustic trapping to monitor the local environmental conditions.
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| 46. |
- Yurgens, Avgust, 1959
(författare)
-
Making thick photoresist SU-8 flat on small substrates
- 2019
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 1361-6439 .- 0960-1317. ; 29:1
-
Tidskriftsartikel (refereegranskat)abstract
- This work suggests a simple method to flatten thick layers (similar to 50-200 mu m) of SU-8 photoresist on small substrates (similar to 1 cm). The method sidesteps the edge beads problem and enables photolithography patterns up to the substrates' edges. Moreover, the method can be used even for substrates with large aspect ratios when the spin coating is largely impossible.
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| 47. |
- Zhao, Jie, et al.
(författare)
-
Microstructure-tunable highly conductive graphene-metal composites achieved by inkjet printing and low temperature annealing
- 2018
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP PUBLISHING LTD. - 0960-1317 .- 1361-6439. ; 28:3
-
Tidskriftsartikel (refereegranskat)abstract
- We present a method for fabricating highly conductive graphene-silver composite films with a tunable microstructure achieved by means of an inkjet printing process and low temperature annealing. This is implemented by starting from an aqueous ink formulation using a reactive silver solution mixed with graphene nanoplatelets (GNPs), followed by inkjet printing deposition and annealing at 100 degrees C for silver formation. Due to the hydrophilic surfaces and the aid of a polymer stabilizer in an aqueous solution, the GNPs are uniformly covered with a silver layer. Simply by adjusting the content of GNPs in the inks, highly conductive GNP/Ag composites (> 106 S m(-1)), with their microstructure changed from a large-area porous network to a compact film, is formed. In addition, the printed composite films show superior quality on a variety of unconventional substrates compared to its counterpart without GNPs. The availability of composite films paves the way to the metallization in different printed devices, e.g. interconnects in printed circuits and electrodes in energy storage devices.
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| 48. |
- Alavian Ghavanini, Farzan, 1978, et al.
(författare)
-
An easy-to-implement method for evaluation of capacitive resonant sensors
- 2006
-
Ingår i: Journal of Micromechanics and Microengineering. - 1361-6439 .- 0960-1317. ; 16:6, s. s156-s160
-
Tidskriftsartikel (refereegranskat)abstract
- A novel method that can be used to characterize resonant capacitive sensors is presented. The method is based on measurement of the third harmonic of the current through the capacitor; thus the detection signal is frequencyseparated from the excitation signal. The measurement is time-continuousand only requires a very simple resonant structure where a single electrode is simultaneously used for excitation and detection. The readout circuit iseasily implemented with a single operational amplifier and standard equipment such as a lock-in amplifier or a function generator and a spectrum analyzer. Measurements of a resonant structure confirm the feasibility of the concept.
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| 49. |
- Andersson, Martin, et al.
(författare)
-
Fracture strength of glass chips for high-pressure microfluidics
- 2016
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Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 26:9
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Tidskriftsartikel (refereegranskat)abstract
- High-pressure microfluidics exposes new areas in chemistry. In this paper, the reliability of transparent borosilicate glass chips is investigated. Two designs of circular cavities are used for fracture strength tests, either 1.6 mm wide with rounded corners to the fluid inlets, or 2.0 mm wide with sharp inlet corners. Two kinds of tests are done, either short-term,e.g. pressurization to fracture at room temperature, or long-term, with fracture at constant pressurization for up to one week, in the temperature region 11–125 °C. The speed of crack fronts is measured using a high-speed camera. Results show fracture stresses in the range of 129 and 254 MPa for short-term measurements. Long-term measurements conclude the presences of a temperature and stress dependent delayed fracture. For a reliability ofone week at 11–38 °C, a pressure limit is found at the lower end of the short-term measurements, or 15% lower than the average. At 80 °C, this pressure limit is 45% lower. Crack speeds are measured to be 10−5 m s-1 during short-term fracture. These measurements are comparable with estimations based on slow crack growth and show that the growth affects the reliability of glass chips. This effect is strongly affected by high temperatures, thus lowers the operating window of high-pressure glass microfluidic devices.
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- Andersson, Martin, et al.
(författare)
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Thin film metal sensors in fusion bonded glass chips for high-pressure microfluidics
- 2017
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Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 27:1
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Tidskriftsartikel (refereegranskat)abstract
- High-pressure microfluidics offers fast analyses of thermodynamic parameters for compressed process solvents. However, microfluidic platforms handling highly compressible supercritical CO2 are difficult to control, and on-chip sensing would offer added control of the devices. Therefore, there is a need to integrate sensors into highly pressure tolerant glass chips. In this paper, thin film Pt sensors were embedded in shallow etched trenches in a glass wafer that was bonded with another glass wafer having microfluidic channels. The devices having sensors integrated into the flow channels sustained pressures up to 220 bar, typical for the operation of supercritical CO2. No leakage from the devices could be found. Integrated temperature sensors were capable of measuring local decompression cooling effects and integrated calorimetric sensors measured flow velocities over the range 0.5-13.8 mm/s. By this, a better control of high-pressure microfluidic platforms has been achieved.
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