| 1. |
- Bodén, Roger, et al.
(author)
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A metallic micropump for high-pressure microfluidics
- 2008
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In: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 18:11, s. 115009-
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Journal article (peer-reviewed)abstract
- This paper presents one of the strongest mechanical sub-cm(3) sized micropumps for microfluidics. It consists of two active valves and one pumping chamber, each operated by a paraffin actuator that is driven by a low-voltage square pulse waveform. The pump is fabricated in a simple process using parylene-coated stainless steel stencils, paraffin and copper clad polyimide. When driving the pump at 0.07 Hz and 2.0 V (0.8 W) per actuator, it pumped water without leakage at a flow rate of 0.75 mu L min(-1) up to above 50 bar (5 MPa) back-pressure. The frequency dependence was evaluated and a maximum flow rate of 1 mu L min(-1) at 0.21 Hz and 1.8 V was observed. A thermomechanical FEM analysis, which was in good agreement with experiments at low frequencies, predicts the behaviour at higher frequencies.
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| 8. |
- Bodén, Roger, 1979-
(author)
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Microactuators for Powerful Pumps
- 2008
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Doctoral thesis (other academic/artistic)abstract
- When paraffin wax melts it exhibits a large, relatively incompressible volume expansion. This can be used in microactuators for strong and large displacements, a rare combination among actuators. Furthermore, paraffin is inexpensive, inert and environmentally friendly, as well as easily processed and actuated. Together, these properties give paraffin actuators great potential for use in both low-cost and high-performance applications.In microfluidics, the miniaturization of various analysis systems decreases the volumes of samples and reagents needed, as well as the analysis throughput time. Using on-chip micropumps increases the efficiency of the microfluidic system, but a challenge for such pumps is the high back-pressure associated with separation, filtration or narrower channels.The objective of this thesis is to increase the understanding of paraffin in microactuators, as well as to further explore its possibilities and limitations. The main application area has been on-chip micropumps.For low-cost applications, actuators, pumps and dispensers have been fabricated in plastics and then evaluated. The dispenser is intended for on-chip storage and dispensing of liquids in a lab-on-a-chip that could be used in, e.g., point-of-care testing (POCT).For high-performance applications, metallic actuators, pumps and dispensers have been accomplished. The micropump is the world’s strongest mechanical micropump in sub-cubic centimetre size, capable of pressures of above 5 MPa. Possible applications are strong microhydraulics, on-chip chromatography, or medical microdosage systems.A limitation of paraffin is the relatively slow thermal actuation. In this thesis the thermal properties have also been turned into an advantage: Directional solidification is used to accomplish multiple stable states of the actuator displacement, withheld without any power consumption.For the future, the high-pressure capability may be improved by new designs. Optimization of speed and power consumption can be made by further work on modelling as well as on drive and control of the heating.
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| 9. |
- Bodén, Roger, et al.
(author)
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On-chip liquid storage and dispensing for lab-on-a-chip applications
- 2008
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In: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 18:7, s. 075036-
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Journal article (peer-reviewed)abstract
- This work presents novel components for on-chip storage and dispensing inside a lab-on-a-chip (LOC) for applications in immunoassay point-of-care testing (POCT), where incubation and washing steps are essential. It involves easy-to-use on-chip solutions for the sequential thermo-hydraulic actuation of liquids. The novel concept of combining the use of a rubber plug, both as a non-return valve cap and as a liquid injection interface of a sealed reservoir, allows simple filling of a sterilized cavity, as well as the storage and dispensing of reagent and washing buffer liquids. Segmenting the flow with air spacers enables effective rinsing and the use of small volumes of on-chip stored liquids. The chip uses low-resistance resistors as heaters in the paraffin actuator, providing the low-voltage actuation that is preferred for handheld battery driven instruments.
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| 10. |
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| 11. |
- Boman, Mats, et al.
(author)
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Laser micromachining
- 2001
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In: Invited talk, Micro- and Nanotechnologies LSU/CAMD Summer School 2001, Baton Rouge, LA, USA. - 2001.
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Conference paper (peer-reviewed)
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| 12. |
- Bruhn, Fredrik, 1976-
(author)
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Miniaturized Multifunctional System Architecture for Satellites and Robotics
- 2005
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Doctoral thesis (other academic/artistic)abstract
- This thesis describes and evaluates the design of nanospacecraft based on advanced multifunctional microsystems building blocks. These systems bring substantial improvements of the performance of nanosatellites and enable new space exploration, e.g. interplanetary science missions using minute space probes. Microsystems, or microelectromechanical systems, allows for extreme miniaturization using heritage from IC industry. Reducing mass and volume of spacecraft gives large savings in terms of launch costs. Definition and categorization of system and module level features in multifunctional microsystems are used to derive a spacecraft optimization algorithm which is compatible with commonly used concurrent engineering methods. The miniaturization of modules enables modular spacecraft architectures comprising powerful multifunctional microsystems, which are applicable to satellites between 10 and 1000’s of kg. This kind of complete spacecraft architecture has been developed for the NanoSpace-1 technology demonstrator satellite. The spacecraft bus uses multifunctional design to enable distributed intelligence and autonomy, graceful degradation, functional surfaces, and distributed power systems. The increase in performance of the new spacecraft architecture as compared with conventional nanosatellites is orders of magnitudes in terms of power storage, scientific payload mass ratio, pointing stabilization, and long time space operation. This high-performance system-of-microsystems architecture has been successfully employed on two space robotic concepts: a miniaturized submersible vehicle for Jupiter’s Moon Europa and a miniaturized spherical robot. The submersible is enabled by miniaturization of electronics into 3-dimensional, vertically integrated multi-chip-modules together with new interconnection methods. These technologies enabled the submersible vehicle tube-shaped design within 20 cm length and 5 cm diameter. The spherical rover was developed for long range and networked science investigations of interplanetary bodies. The rover weighs 3.5 kg and is shown to endure direct reentry on Mars, which increases the ratio between the landed mobile payload mass and the initial mass in Mars orbit by a factor of 18.
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| 13. |
- Hjort, Klas, 1964-, et al.
(author)
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Micromachining in bulk GaAs
- 1990
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In: Sensors and materials. - 0914-4935. ; 2, s. 1-
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Journal article (peer-reviewed)
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| 14. |
- Klintberg, Lena, et al.
(author)
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A large stroke, high force paraffin phase transition actuator
- 2002
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In: Sensors and Actuators A-Physical. - 0924-4247 .- 1873-3069. ; 96:2-3, s. 189-195
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Journal article (peer-reviewed)abstract
- An actuator that uses the volume expansion related to the solid-to-liquid phase transition of paraffin wax has been fabricated and evaluated. The actuator consists of a ring-shaped paraffin cavity confined by two joint silicon diaphragms with rigid centers. When the paraffin is melted, the resulting hydrostatic pressure deflects the joined rigid centers in one direction only. The magnitude of the deflection is primarily a function of the geometrical relation between the two diaphragms, giving the opportunity to tailor the behavior of the actuator in a large range. Conventional IC-processing techniques have been used to fabricate a prototype with a width of 68 mm and a thickness of 825 μm. The prototype attained a maximum deflection of ca. 90 μm. Loaded with 3 N it still exhibits a deflection of ca. 75 μm. The device can be used as a thermal switch.
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| 15. |
- Lehto, Marcus, et al.
(author)
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A polymeric paraffin microactuator
- 2008
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In: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 17:5, s. 1172-1177
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Journal article (peer-reviewed)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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| 16. |
- Lehto, Marcus, et al.
(author)
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Binary mixtures of n-alkanes for tunable thermohydraulic microactuators
- 2007
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In: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 16:3, s. 728-733
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Journal article (peer-reviewed)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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| 17. |
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| 18. |
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| 19. |
- Lehto, Marcus, et al.
(author)
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Rapid prototyping of a polymeric paraffin microactuator
- 2008
-
In: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 17:5, s. 1172-1177
-
Journal article (peer-reviewed)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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| 20. |
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| 21. |
- Schweitz, Jan-Åke
(author)
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Dark source flux, dark energy and the expansion of the flat universe
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Other publication (other academic/artistic)abstract
- Recent WMAC and Planck data confirm that the universe is spatially flat also in a General Relativity framework. This article aims at demonstrating that in the flat-metric, uniform universe approximation, a new set of initial assumptions – consistent with earlier and recent observations – results in a simple, rigorous expansion theory, free-standing from General Relativity and readily explaining the observed expansion features of the universe, both qualitatively and quantitatively. A Big Bang singularity and the existence of a non-zero ground level density of dark energy permeating all space and being a physical manifestation of the invariant ground state space, follows from the theory. The basic hypothesis is that the universe is inflated by a uniformly distributed source flux of dark energy – a dark source flux – generating the observed volume expansion. This source flux makes possible a concise mathematical formulation of the metric expansion in terms of one single variable (cosmic time) and two measurable universal constants. The model completely determines the evolution of the universe from Big Bang to eternity and provides a seamless connection between the early epoch of rapid inflation and our present epoch of slower but accelerating expansion. It features a transition from decelerating to accelerating expansion in an interval of time consistent with astrophysical observations. All expansion parameters – including total density and dark energy density – are derived and evaluated from merely two experimental input parameters: a measured Hubble constant and the age of the universe estimated from the age of the oldest known star. The numerical results are well in line with recent WMAP and Planck results, but in contrast to these do not rely on best-fit procedures. The model also reveals an intimate relation between the dark energy and the matter contents of the universe. The dark source flux defines a cosmological arrow of time and opens up a new and tangible physical perspective in the understanding of the evolution of the expanding universe.
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| 22. |
- Schweitz, Jan-Åke, 1945-
(author)
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Does the Planck unit system relate to a non-singular primordial state of the universe?
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Other publication (other academic/artistic)abstract
- Recently, a new model for flat-metric expansion of the universe that eliminates several problems arising in the expansion theory of standard cosmology was presented. In the original version of this dark source flux (DSF) model, Big Bang is manifested by a mathematical singularity with infinite initial matter density and infinite initial expansion rate. However, an integration constant (a time shift) with extremely small value was for simplicity set equal to zero in this theory. A closer analysis reveals that if this constant is assigned a very small nonzero value, Big Bang will not have started from a mathematical singularity, but from a primordial state of extremely high, yet limited density and expansion rate. This primordial state constitutes a non-singular Planck epoch of extremely short duration. It turns out that all primordial state parameters assume values of the order of Planck units. Thus, the Planck unit system may have found an attractive physical significance: it relates to the primordial Planck state of the universe where the three fundamental theories of physics merge.There is a well known, puzzling ratio (of the order 10120) between ground state (‘vacuum’) density values based on quantum field theory on one hand, and experimental values derived from ΛCDM (or DSF) on the other. This discrepancy has been called the worst theoretical prediction in the history of science. The present article offers a possible explanation to this issue.
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| 23. |
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| 24. |
- Schweitz, Jan-Åke, 1945-
(author)
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Expansion of the universe : Back to basics (updated version)
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Other publication (other academic/artistic)abstract
- The ambition of this article is to establish a fundamental model of our expanding universe in a minimalistic spirit, and show that a simple source flux model actually agrees just as well with observed expansion data as General Relativity and its offspring Standard Cosmology do. The theory is based on three constitutive equations, relating three basic expansion parameters to each other. Vacuum energy is interpreted as kinetic expansion energy, thereby eliminating the need for a cosmological constant corresponding to dark energy with abnormal negative pressure. Expansion parameters in good agreement with WMAP and Planck results are derived from one single experimental input value (the present Hubble parameter). A strong relationship between vacuum energy and other energy species in the universe is revealed. The model eliminates the so-called flatness, horizon and coincidence issues, and yields singular and non-singular Big Bang solutions; the Planck unit system being closely linked to the non-singular primordial state of the universe. Furthermore, the ‘worst theoretical prediction in the history of science’ (error factor 10120 ) may be explained by this theory.
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| 25. |
- Schweitz, Jan-Åke, 1945-
(author)
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Non-Relativistic Expansion Of The Flat Universe
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Other publication (other academic/artistic)abstract
- A detailed analysis shows that the principle of energy conservation – presumed in General Relativity (GR) – simply does not hold in an unlimited universe undergoing spatially flat-metric, accelerating expansion. For this reason, a new non-GR model for the expanding universe is developed from basics. It is based on recent observational results and the model is established in the minimalist spirit of Occam’s razor. The non-inertial, accelerating expansion of the spatially flat universe is proposed to be driven by a non-conservative influx of new energy, in natural agreement with commonly accepted physics, and vacuum energy is identified as the kinetic expansion energy of the universe. (This source flux is fundamentally different from the one proposed by Hoyle and others in the Steady State Model.) A Big Bang beginning is predicted and the observed expansion features of the universe are readily explained, qualitatively as well as numerically. A new, strong relationship between vacuum energy and other cosmic media is revealed. The theory yields singular and non-singular Big Bang solutions; the Planck unit system being closely linked to the non-singular primordial state of the universe. This new model is less restricted than standard cosmology and shows better predictive power.
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| 26. |
- Schweitz, Jan-Åke
(author)
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Pressure in cosmic source flux theory
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Other publication (other academic/artistic)abstract
- A cosmological pressure concept is defined from virial equations for open systems undergoing Hubble expansion. A uniform cosmic source flux model is assumed, comprising non-relativistic baryonic and dark matter (‘dust’); relativistic radiation; and vacuum energy. The pressures thus derived are compared with corresponding pressures derived from the Friedmann equation in standard cosmology. The pressures are found to agree for non-relativistic matter and relativistic radiation, but differ for vacuum energy. The ‘exotic’ negative pressure of dark energy in standard cosmology is replaced by more down-to-earth positive pressure of vacuum energy in the present theory. The reason for this deviation is that the local energy conservation criterion, which is built into the field equation in general relativity, is replaced by a compelling consequence of Hubble’s law: the criterion for balanced expansion. In the choice between questionable energy conservation in an accelerating system on one hand, and the experimentally verified Hubble’s law on the other, the latter is chosen in the present analysis.
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| 27. |
- Schweitz, Jan-Åke, 1945-
(author)
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Tiden, källflödet och universums expansion – skapelse utan slut (uppdaterad version)
-
Other publication (pop. science, debate, etc.)abstract
- Ambitionen med denna skrift är att – helt fristående från allmänna relativitetsteorin – bygga en modell av vårt expanderande universum i minimalistisk anda, och demonstrera att denna enkla modell faktiskt stämmer lika bra med observerade expansionsdata som allmänna relativitetsteorins och standardkosmologins mycket mer komplicerade modeller gör. Jag bygger systematiskt upp min modell från grunden till en sammansatt teori, som är beroende av en enda variabel (kosmisk tid) och två universella konstanter. Teorin baseras på tre enkla, konstitutiva samband mellan tre grundläggande expansionsparametrar, samt ett litet antal väl motiverade begynnelsevillkor – postulat – som ligger helt i linje med astronomiska observationer. En extrem förenkling jämfört med andra expansionsteorier är att jag bara behöver ett enda experimentellt värde (dagens expansionshastighet) för att beräkna värden på alla övriga expansionsparametrar, inklusive den mörka energins (vakuumenergins) täthet, vilken hamnar mycket nära WMAP- och Planckmissionernas värden. Jag kommer i denna teori visa att ett antal kända problem inom standardkosmologin kan undvikas och många nya insikter uppnås.Jag vill här bjuda läsaren på en svindlande färd från universums dramatiska begynnelse i Big Bang, genom våra hyfsat överblickbara årmiljarder nära vår stund på jorden, fram mot ett blekt, stillsamt utflöde av tiden många årmiljarder framåt.
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| 28. |
- Svedberg, Malin, 1972-
(author)
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Microstructures for Chemical Analysis : Design, Fabrication and Characterisation
- 2005
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Doctoral thesis (other academic/artistic)abstract
- The interest for miniaturisation in chemical and biological analysis has increased in recent years. In this work, the design, fabrication and characterisation of tools for microanalysis have been studied. The focus is set on polymer microchips for applications in chemical analysis. The work consists of three parts: design and fabrication of paraffin microactuators, design and fabrication of polymer microchips as interfaces in electrospray ionisation mass spectrometry (ESI-MS), and characterisation of conducting films for fused silica capillaries as interfaces in ESI-MS.The principle of the paraffin actuators is based on the volume increase resulting from paraffin melting. Paraffin expansion is utilised to cause membrane deflection. The first plastic microactuator using paraffin as the actuator material was successfully demonstrated.The microchips as interfaces in ESI-MS have been designed with the objective that the interface should be as much a part of the microchip as possible, and as to as large extent as possible, be fabricated in the same step as the microchannels. Sheathless electrospray from microchips was demonstrated for the first time. In addition a simplified fabrication process for ESI-MS interfaces in poly(dimethyl siloxane) (PDMS) was developed.The degradation of conductive coatings for sheathless ESI-MS on fused silica capillaries was studied. It was shown that electrochemical experiments could successfully be used to simulate the electrospray conditions and predict the failure of different gold coatings.It was concluded that a common issue in the fabrication of thermoplastic microchips is the crucial sealing of microchannels and cavities. From this point of view, PDMS is a more advantageous material in microfluidics.
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| 29. |
- Thornell, Greger, et al.
(author)
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Residual stress in sputtered gold films on quartz measured by the cantilever beam deflection technique
- 1999
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In: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. - 0885-3010 .- 1525-8955. ; 46:4, s. 981-992
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Journal article (peer-reviewed)abstract
- With resonator applications in mind, the residual stress in sputtered gold electrodes on quartz has been investigated with respect to varioiis deposition rates (2, 10, and 50 A/s), pressures (1.0 and 3 0- mbar), deposition temperatures (80OC and room temperature (RT)), film thicknesses (approx. 400 to 800 A), and substrate smoothnesses (lapped and polished), u:;ing the cantilever beam deflection method. Samples were monitored for 4 weeks at room temperature followed by 13 weeks of annealing at 85OC. The initial stress (ranging from -180 to -60 MPa) was compressive for all samples but turned tensile (a few megapascals) in some of the samples after annealing. A significant decrease in initial compressive stress appeared with samples coated at an elevated temperature. From samples preparecd at lower pressure and differing only in film thickness and substrate roughness, an increased compressive stress was found in thicker films and on rougher surfaces. The stress relaxation has been fitted to an exponential expression, and an attempt to relate the stress to a frequency shift (typically a few parts per million for ordinary, 100-pm thick AT blanks) has been made. With the help of transmission electron microscopy (TEM) the film morphology was investigated and related to the deposition parameters and aging. Judging from the increase in compressive stress and grain refinement with increased deposition rate and decreased pressure the atomic peening mechanism is the most likely reascm for the induced stress. Rutherford backscattering spectrometry (RBS) was employed to rule our the inclusion oj- argon (below or around 0.5%) as an explanation. From the vague, but clearly discernible, trend toward faster RT stress relaxation with higher initial stress, together with the liner film morphology, the relief mechaniism is believed to he stress-promoted grain boundary diffusion.
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