| 1. |
|
|
| 2. |
- Tavakoli Dastjerdi, Mohammad Hadi, 1984, et al.
(författare)
-
InGaAs/InAlAs/AlAs Heterostructure Barrier Varactors on Silicon Substrate
- 2011
-
Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 32:2, s. 140-142
-
Tidskriftsartikel (refereegranskat)abstract
- We present the results of a study on epitaxial transferof InP-based heterostructure barrier varactor (HBV) materials onto a silicon substrate employing the low-temperature plasma activated bonding technique. The test diodes fabricated on the bonded samples exhibit symmetric electrical characteristics, over the temperature range of 25 ˚C–165 ˚C, and show no degradation compared to previously reported InP-based diodes. Moreover, the onset temperature for debonding, the effective barrier height extracted from the measured data, and the maximum voltage of the HBVs for a current density of 100 A/cm2 were extracted to be 260 ˚C, 0.56 eV, and 10.5 V, respectively.
|
|
| 3. |
- Tavakoli Dastjerdi, Mohammad Hadi, 1984, et al.
(författare)
-
Transfer of InP-based HBV epitaxy onto borosilicate glass substrate by anodic bonding
- 2010
-
Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 46:14, s. 1013-1014
-
Tidskriftsartikel (refereegranskat)abstract
- We present a new fabrication process for epitaxial transfer of InP-based heterostructure barrier varactor diodes, as high frequency varactor multipliers, onto low-dielectric borosilicate glass substrate, employing anodic bonding. The fabricated diodes on the new host substrate display symmetric electrical characteristics with only minor differences compared to those of the reference devices on the original InP substrate.
|
|
| 4. |
|
|
| 5. |
- Amirfeiz, Petra, 1973, et al.
(författare)
-
Hydrophobic low temperature wafer bonding; void formation in the oxide free interface
- 2003
-
Ingår i: Proc. of the 7th Int. Symp. on Semiconductor Wafer Bonding. ; 19, s. 267-
-
Konferensbidrag (refereegranskat)abstract
- The objective is to investigate plasma assisted bonding processes having the potential of forming oxide-free bonded interfaces. Spontaneous low temperature hydrophobic bonding was achieved using a plasma-assisted technique. High surface energy was obtained when bonding two silicon wafers after argon plasma treatment and a subsequent dip in concentrated HF. In contrast hydrogen plasma caused bonding problems while a mix of hydrogen and nitrogen improved the bondability. A particular interest is directed toward the generation of voids as a consequence of storage at room temperature or low temperature annealing. All samples suffer from void generation both after storage at room temperature and after low temperature annealing.
|
|
| 6. |
|
|
| 7. |
- Bring, Martin, 1977, et al.
(författare)
-
Method for measuring fracture toughness of wafer-bonded interfaces with high spatial resolution
- 2006
-
Ingår i: Journal of Micromechanics and Microengineering. - 1361-6439 .- 0960-1317. ; 16:6, s. 68-74
-
Tidskriftsartikel (refereegranskat)abstract
- A test method for adhesion quantification with high spatial resolution of bonded areas is presented. The method is based on a three-point bend chevron test and is applicable especially for small bonded structures. Using an ordinary surface profiler the method is suitable for determining the mode I fracture toughness, K Ic , of bonded areas from 5 × 5 νm 2 to 20 × 20 νm 2 in size. The method is compared quantitatively to the double cantilever beam (DCB) test. Measurements show that the average K Ic value determined using this method is in close accordance with K Ic values measured using the DCB method but a larger spread is observed which may be dedicated to a real spatial variation of K Ic shown by the higher spatial resolution of the presented method. © 2006 IOP Publishing Ltd.
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
| 11. |
- Chang, S, et al.
(författare)
-
An electrowetting-based microfluidic platform for magnetic bioassays
- 2010
-
Ingår i: The 14th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2010, 3-7 Oktober, Groningen, Neterlands. - 9781618390622 ; 2, s. 1331-1333
-
Konferensbidrag (refereegranskat)abstract
- Here we present our recent work on a droplet-based microfluidic device for manipulating microliter-sized droplets. By replacing the formerly used common dielectric SiO2 with Si3N4 and applying a 33 nm thick Teflon top layer to create a hydrophobic surface, we successfully lowered the actuation voltage from 450 V to 50 Vdc/40 Vac. Sputtered HfO2 with high dielectric constant was also investigated as an insulator, which could reproducibly yield thin defect-free insulation layers and lower the actuation voltage to less than 40 V.
|
|
| 12. |
|
|
| 13. |
- Enoksson, Peter, 1957, et al.
(författare)
-
Micro- and Nanosystems for Sensing in Medicine
- 2008
-
Ingår i: Proceedings of Medicinteknikdagarna 2008, 14-15 October, Göteborg, Sweden. ; , s. 117-
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
|
|
| 14. |
- Enoksson, Peter, 1957, et al.
(författare)
-
Wafer bonding for MEMS
- 2005
-
Ingår i: Proceeding of the 9th International Symposium on Semiconductor Wafer Bonding: Science, Technology and Applic, Canadaations, Quebec City.
-
Konferensbidrag (refereegranskat)
|
|
| 15. |
- Farjana, Sadia, 1983, et al.
(författare)
-
Conductivity-Dependent Strain Response of Carbon Nanotube Treated Bacterial Nanocellulose
- 2013
-
Ingår i: Journal of Sensors. - : Hindawi Limited. - 1687-7268 .- 1687-725X.
-
Tidskriftsartikel (refereegranskat)abstract
- This paper reports the strain sensitivity of flexible, electrically conductive, and nanostructured cellulose which was prepared by modification of bacterial cellulose with double-walled carbon nanotubes (DWCNTs) and multiwalled carbon nanotubes (MWCNTs). The electrical conductivity depends on the modifying agent and its dispersion process. The conductivity of the samples obtained from bacterial cellulose (BNC) pellicles modified with DWCNT was in the range from 0.034 S·cm−1 to 0.39 S·cm−1, and for BNC pellicles modified with MWCNTs it was from 0.12 S·cm−1 to 1.6 S·cm−1. The strain-induced electromechanical response, resistance versus strain, was monitored during the application of tensile force in order to study the sensitivity of the modified nanocellulose. A maximum gauge factor of 252 was found from the highest conductive sample treated by MWCNT. It has been observed that the sensitivity of the sample depends on the conductivity of the modified cellulose.
|
|
| 16. |
|
|
| 17. |
- Jansson, Anna, 1985, et al.
(författare)
-
Monitoring the osmotic response of single yeast cells through force measurement in the environmental scanning electron microscope
- 2014
-
Ingår i: Measurement science and technology. - : IOP Publishing. - 0957-0233 .- 1361-6501. ; 25:2
-
Tidskriftsartikel (refereegranskat)abstract
- We present a measurement system that combines an environmental scanning electron microscope (ESEM) and an atomic force microscope (AFM). This combination enables studies of static and dynamic mechanical properties of hydrated specimens, such as individual living cells. The integrated AFM sensor provides direct and continuous force measurement based on piezoresistive force transduction, allowing the recording of events in the millisecond range. The in situ ESEM-AFM setup was used to study Pichia pastoris wild-type yeast cells. For the first time, a quantified measure of the osmotic response of an individual yeast cell inside an ESEM is presented. With this technique, cell size changes due to humidity variations can be monitored with nanometre accuracy. In addition, mechanical properties were extracted from load-displacement curves. A Young's modulus of 13-15 MPa was obtained for the P. pastoris yeast cells. The developed method is highly interesting as a complementary tool for the screening of drugs directed towards cellular water transport activity and provides new possibilities of studying mechanosensitive regulation of aquaporins.
|
|
| 18. |
- Jansson, Anna, 1985, et al.
(författare)
-
Novel Method for Controlled Wetting of Materials in the Environmental Scanning Electron Microscope
- 2013
-
Ingår i: Microscopy and Microanalysis. - 1435-8115 .- 1431-9276. ; 19:1, s. 30-37
-
Tidskriftsartikel (refereegranskat)abstract
- Environmental scanning electron microscopy has been extensively used for studying the wetting properties of different materials. For some types of investigation, however, the traditional ways of conducting in situ dynamic wetting experiments do not offer sufficient control over the wetting process. Here, we present a novel method for controlled wetting of materials in the environmental scanning electron microscope (ESEM). It offers improved control of the point of interaction between the water and the specimen and renders it more accessible for imaging. It also enables the study of water transport through a material by direct imaging. The method is based on the use of a piezo-driven nanomanipulator to bring a specimen in contact with a water reservoir in the ESEM chamber. The water reservoir is established by local condensation on a Peltier-cooled surface. A fixture was designed to make the experimental setup compatible with the standard Peltier cooling stage of the microscope. The developed technique was successfully applied to individual cellulose fibers, and the absorption and transport of water by individual cellulose fibers were imaged.
|
|
| 19. |
- Kalaboukhov, Alexei, 1975, et al.
(författare)
-
Operation of a high-T-C SQUID gradiometer with a two-stage MEMS-based Joule-Thomson micro-cooler
- 2016
-
Ingår i: Superconductor Science and Technology. - : IOP Publishing. - 0953-2048 .- 1361-6668. ; 29:9
-
Tidskriftsartikel (refereegranskat)abstract
- Practical applications of high-T-C superconducting quantum interference devices (SQUIDs) require cheap, simple in operation, and cryogen-free cooling. Mechanical cryo-coolers are generally not suitable for operation with SQUIDs due to their inherent magnetic and vibrational noise. In this work, we utilized a commercial Joule-Thomson microfluidic two-stage cooling system with base temperature of 75 K. We achieved successful operation of a bicrystal high-T-C SQUID gradiometer in shielded magnetic environment. The micro-cooler head contains neither moving nor magnetic parts, and thus does not affect magnetic flux noise of the SQUID even at low frequencies. Our results demonstrate that such a microfluidic cooling system is a promising technology for cooling of high-T-C SQUIDs in practical applications such as magnetic bioassays.
|
|
| 20. |
- Kuzmenko, Volodymyr, 1987, et al.
(författare)
-
Tailor-made conductive inks from cellulose nanofibrils for 3D printing of neural guidelines
- 2018
-
Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617. ; 189, s. 22-30
-
Tidskriftsartikel (refereegranskat)abstract
- Neural tissue engineering (TE), an innovative biomedical method of brain study, is very dependent on scaffolds that support cell development into a functional tissue. Recently, 3D patterned scaffolds for neural TE have shown significant positive effects on cells by a more realistic mimicking of actual neural tissue. In this work, we present a conductive nanocellulose-based ink for 3D printing of neural TE scaffolds. It is demonstrated that by using cellulose nanofibrils and carbon nanotubes as ink constituents, it is possible to print guidelines with a diameter below 1 mm and electrical conductivity of 3.8 × 10 −1 S cm −1 . The cell culture studies reveal that neural cells prefer to attach, proliferate, and differentiate on the 3D printed conductive guidelines. To our knowledge, this is the first research effort devoted to using cost-effective cellulosic 3D printed structures in neural TE, and we suppose that much more will arise in the near future.
|
|
| 21. |
- Lindqvist, Camilla, 1985, et al.
(författare)
-
Fullerene Nucleating Agents: A Route Towards Thermally Stable Photovoltaic Blends
- 2014
-
Ingår i: Advanced Energy Materials. - : Wiley. - 1614-6840 .- 1614-6832. ; 4:9, s. 1301437-
-
Tidskriftsartikel (refereegranskat)abstract
- The bulk-heterojunction nanostructure of non-crystalline polymer: fullerene blends has the tendency to rapidly coarsen when heated above its glass transition temperature, which represents an important degradation mechanism. We demonstrate that fullerene nucleating agents can be used to thermally arrest the nanostructure of photovoltaic blends that comprise a non-crystalline thiophene-quinoxaline copolymer and the widely used fullerene derivative [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM). To this end, C-60 fullerene is employed to efficiently nucleate PCBM crystallization. Sub-micrometer-sized fullerene crystals are formed when as little as 2 wt% C-60 with respect to PCBM is added to the blend. These reach an average size of only 200 nanometers upon introduction of more than 8 wt% C-60. Solar cells based on C-60-nucleated blends indicate significantly improved thermal stability of the bulk-heterojunction nanostructure even after annealing at an elevated temperature of 130 degrees C, which lies above the glass transition temperature of the blend. Moreover, we find that various other compounds, including C-70 fullerene, single-walled carbon nanotubes, and sodium benzoate, as well as a number of commercial nucleating agents-commonly used to clarify isotactic polypropylene-permit to control crystallization of the fullerene phase.
|
|
| 22. |
- Lindqvist, Camilla, 1985, et al.
(författare)
-
Nucleation-limited fullerene crystallisation in a polymer–fullerene bulk-heterojunction blend
- 2013
-
Ingår i: Journal of Materials Chemistry A. - 2050-7488 .- 2050-7496. ; 1:24, s. 7174-7180
-
Tidskriftsartikel (refereegranskat)abstract
- The nucleation and growth kinetics of fullerene crystals in thin films of a polymer:fullerene bulk-heterojunction blend are investigated. We find that both processes are strongly diffusion-limited at 100–110 °C due to the proximity to the glass transition temperatures of the blend components. Whereas the growth rate exponentially increases with temperature up to 230 °C, the nucleation rate displays a broad maximum around 150–170 °C, which coincides with the highest rate of fullerene crystallisation. A time-temperature-transformation (TTT) diagram reveals that across the investigated range of temperatures the low rate of nucleation is responsible for the formation of micrometre-sized crystals, which can be detrimental for polymer solar cells. Thus, we identify the lack of sufficient nucleation, which predominantly occurs on the substrate interface, as the origin of this important degradation mechanism.
|
|
| 23. |
- Naboka, Olga, 1981, et al.
(författare)
-
Carbon Nanofibers Synthesized from Electrospun Cellulose for Advanced Materials Applications
- 2013
-
Ingår i: Materials Science Forum. - 1662-9752 .- 0255-5476. ; 730-732, s. 903-908
-
Konferensbidrag (refereegranskat)abstract
- Carbon nanofibrous sheets (conductivity 1.9 to 35.5 S×cm-1, water contact angle up to 137°) consisting of amorphous fibers with diameter of 20 - 150 nm (C:O atomic ratio 25.4 - 86.0) were synthesized by carbonization of cellulose regenerated from electrospun cellulose acetate mats with three methods of alkaline deacetylation. It was established that C:O atomic ratio, conductivity and hydrophobicity depended on the regeneration method and on the temperature of carbonization. The highest flexibility, lowest conductivity and lowest water contact angle was observed for carbon synthesized from cellulose regenerated with NaOH in ethanol (0.05 mol/l) for 24 hours at room temperature. The highest conductivity, highest water contact angle and lowest flexibility was observed for carbon synthesized from cellulose regenerated with water solution of NaOH/NaCl (3.75 M NaOH, 2.1 M NaCl) during 15 minutes at 65°C.
|
|
| 24. |
|
|
| 25. |
- Naboka, Olga, 1981, et al.
(författare)
-
Cobalt (II) Chloride Promoted Formation of Honeycomb Patterned Cellulose Acetate Films
- 2012
-
Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 367:1, s. 485-493
-
Tidskriftsartikel (refereegranskat)abstract
- CoCl2 containing honeycomb patterned films were prepared from cellulose acetate (CA)/CoCl2/acetone solutions by the breath figure method in a wide range of humidities. Size and pore regularity depend on the CA/CoCl2 molar ratio and humidity. When replacing CoCl2 with Co(NO3)2 or CoBr2, no formation of ordered porosity in the cellulose acetate films is observed. According to data from scanning electron microscopy (SEM), Energy Dispersive X-ray Microanalysis (EDX), X-ray Diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy, the key role in the formation of honeycomb structures can be attributed to the physical and chemical properties of CoCl2 – hygroscopicity, low interaction with CA, and extraction from CA/CoCl2/acetone solution by water droplets condensed on the surface of the CA/CoCl2 solution. Obtained films are prospective for using in catalysis, hydrogen fuel cells, and optical sensing materials.
|
|
| 26. |
|
|
| 27. |
- Naboka, Olga, 1981, et al.
(författare)
-
Ni/C/SiO2 nanostructured composites synthesized by carbonization of carboxymethyl cellulose
- 2012
-
Ingår i: ECCM 15 - 15th European Conference On Composite Materials, 24-28 June 2012, Venice, Italy, paper 1052 (1-7).. ; 367:1, s. 485-493
-
Konferensbidrag (refereegranskat)abstract
- Ni/C/SiO2 porous composites were synthesized by one-pot approach by carbonization of sodium carboxymethyl cellulose/SiO2 xerogels containing NiCl2. Synthesized composites are mesoporous materials (average pore size 11.8 -15.1 nm) with the surface area 72.1 – 91.1 m2. Ni nanoparticles of 30-90 nm in diameter are evenly distributed within the volume of composites. The hydrogen sorption capacity at -196°C and 20 bar measured for as-synthesized samples was up to 0,32%.
|
|
| 28. |
- Nafari, Alexandra, 1980, et al.
(författare)
-
Combining Scanning Probe Microscopy and Transmission Electron Microscopy
- 2011
-
Ingår i: Scanning Probe Microscopy in Nanoscience and Nanotechnology. - 9783642104961 ; , s. 59-134
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter is a review of an in situ method where a scanning electron microscope (SPM) has been combined with a transmission electron microscope (TEM). By inserting a miniaturized SPM inside a TEM, a large set of open problems can be addressed and, perhaps more importantly, one may start to think about experiments in a new kind of laboratory, an in situ TEM probing laboratory, where the TEM is transformed from a microscope for still images to a real-time local probing tool. In this method, called TEMSPM, the TEM is used for imaging and analysis of a sample and SPM tip, while the SPM is used for probing of electrical and mechanical properties or for local manipulation of the sample. This chapter covers both instrumental and application aspects of TEMSPM.
|
|
| 29. |
|
|
| 30. |
- Nafari, Alexandra, 1980, et al.
(författare)
-
MEMS sensor for in situ TEM-nanoindentation with simultaneous force and current measurements
- 2009
-
Ingår i: MicroMechanics Europe 2009. ; , s. 4-
-
Konferensbidrag (refereegranskat)abstract
- Nanoindentation is a material testing method frequently used for studies of mechanical properties on the nano scale. Today, nanoindentation is also performed in situ a Transmission Electron Microscope (TEM), in order to simultaneously monitor the substrate with high resolution imaging. Here we present an extension of TEM-Nanoindention, utilizing custom designed MEMS sensor for in situ TEM use that enables simultaneous force and current measurements. The sensor is intended to be operated in electrostatic feedback mode and enable ultra high resolution TEM imaging. The design and fabrication of the sensor is presented here. Preliminary measurements show that the fabrication has been successful.
|
|
| 31. |
|
|
| 32. |
- Raeissi, Bahman, 1979, et al.
(författare)
-
Relation between Electrical and Mechanical Characteristics of Low-Temperature Bonded Si/Si Interfaces
- 2006
-
Ingår i: Proceeding of 210th ECS Meeting, Semiconductor Wafer Bonding 9: Science, Technology, and Applications, Vol. 3, No .6. - : The Electrochemical Society. ; 3:6, s. 217-226
-
Tidskriftsartikel (refereegranskat)abstract
- The bonding energy of low-temperature plasma bonded silicon-silicon interfaces is correlated with their electrical properties. From current versus voltage and capacitance versus voltage data, mobile ion charges are shown to play a considerable role for the bond force. By comparing the evolution of the bonding strength during the first 48 hours after bonding with that of ionic charge in the interlayer and interface electron state concentrations, we demonstrate a relation between these quantities for low temperature plasma bonded silicon surfaces. The results suggest that mobile ions in an interfacial layer change the charge distribution, resistance, capacitance, interface state density distributions and correlate with the bonding energy of the silicon-silicon junction.
|
|
| 33. |
- Raeissi, Bahman, 1979, et al.
(författare)
-
The Role of Mobile Charge in Oxygen Plasma-Enhanced Silicon-to-Silicon Wafer Bonding
- 2010
-
Ingår i: Electrochemical and Solid-State Letters. - : The Electrochemical Society. - 1099-0062. ; 13:6, s. H179-H181
-
Tidskriftsartikel (refereegranskat)abstract
- Mechanical bonding energies of oxygen plasma treated and room-temperature wafer bonded silicon surfaces have been measured as a function of storage time in parallel with measurements of electrical interface properties. The surface energy increases with time dependence similar to that of decreasing interface state concentration. The current vs voltage behavior reveals the existence of mobile ions. We suggest that these mobile charges, after the reaction with the interface states, give rise to the increased surface energy responsible for bonding.
|
|
| 34. |
- Raeissi, Bahman, 1979, et al.
(författare)
-
Wafer bonding strength increased by mobile ions
- 2009
-
Ingår i: Proceeding of EUROSOI 2009. ; , s. 99-100
-
Konferensbidrag (refereegranskat)abstract
- Mechanical bonding energies of oxygen plasma treated androom temperature wafer bonded silicon surfaces have beenmeasured as a function of storage time in parallel withmeasurements of electrical interface properties. We find that the surface energy increases with a time dependence similar to that of decreasing interface state concentration. The current versus voltage behaviour reveals the existence of mobile ions. We conclude that these mobile charges after reaction with the interface states give rise to the increased surface energy responsible for the bonding.
|
|
| 35. |
|
|
| 36. |
- Sanz-Velasco, Anke, 1971, et al.
(författare)
-
Low-Temperature Direct Wafer Bonding
- 2012
-
Ingår i: Lattice Engineering: Technology and Applications. ; , s. 135-187
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The breakthrough of directwafer bondingwas achieved with siliconon-insulator (SOI) allowing for high-power and high-frequency electronics, microelectronics components with low energy consumption. After this, several bonding techniques have been developed (e.g. silicon direct bonding, anodic bonding) and are being developed (e.g. low-temperature plasma-assisted direct bonding) to achieve hybrid components, as III-V semiconductors on silicon-based substrates, monolithic integration of optoelectronic devices with high-speed silicon integrated circuits, three-dimensional stacking of integrated circuits (ICs) or circuits transfer onto a varietyof substrates. An overview of more recent activities on several techniques for attaining low-temperature bonding is presented.
|
|
| 37. |
|
|
| 38. |
|
|
| 39. |
- Sanz-Velasco, Anke, 1971
(författare)
-
The RDGT - Integration of Micromechanics and Electronics by Plasma Assisted Wafer Bonding
- 2002
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A high-resolution capacitive sensing technique is presented in this thesis: the Resonant Double Gate Transistor (RDGT). The major advantage of the RDGT compared to "pure" capacitive sensing techniques is its low output impedance because of the direct capacitance to current conversion of the transistor. The important difference between the Resonant Gate Transistors (RGT) reported earlier and the RDGT is that in addition to the oscillating gate there is also a fixed gate. The additional gate provides long- term stability and makes possible a choice of the working point of the transistor independent of the bias applied to the oscillating gate. According to simulations the RDGT provides a spatial resolution of the order of 10-13 m Hz-1/2 with an air gap of 2 µm and a DC voltage of 10 V on the oscillating gate. First measurements on fabricated RDGT´s resulted in a spatial resolution of 2 x 10-11 m Hz-1/2. Oxygen plasma assisted wafer bonding is evaluated as a tool for integrating micromechanics with electronics such as the RDGT. Our oxygen plasma enhanced wafer bonding using ICP RIE results in high surface energies after storage for 24 hours at room temperature. The surface energies achieved are comparable to the surface energies obtained when wet chemical cleaned and bonded wafers are annealed at 800 °C. Investigations were carried out to understand the plasma assisted bonding mechanism. We propose that a porous silica network resulting from the plasma treatment makes faster diffusion of water through a porous network possible. This makes it easier for hydroxyl groups to come into contact for reaction, which gradually increases the surface energy at room temperature. The first electrical characterisation of ASIC´s with standard electronic components and circuits after oxygen plasma treatment using an ICP RIE showed no degradation of their performance. Based on the measurement results it is very likely that our oxygen plasma assisted room temperature bonding is CMOS compatible. Finally, a technology with the potential of integrating the high resolution detection method for oscillating structures, the RDGT, with bulk micromachined devices by room temperature oxygen plasma assisted wafer bonding using RIE is presented.
|
|
| 40. |
|
|
| 41. |
- Schaller, Vincent, 1979, et al.
(författare)
-
Determination of nanocrystal size distribution in magnetic multicore particles including dipole-dipole interactions and magnetic anisotropy: A Monte Carlo study
- 2010
-
Ingår i: AIP Conference Proceedings. - : AIP. - 1551-7616 .- 0094-243X. - 9780735408661 ; 1311, s. 42-50
-
Konferensbidrag (refereegranskat)abstract
- A correct estimate of the size distribution (i.e., median diameter D and geometric standard deviation σ) of the magnetic nanocrystals (MNCs) embedded in magnetic multicore particles is a necessity in most applications relying on the magnetic response of these particles. In this paper we use a Monte Carlo method to simulate the equilibrium magnetization of two types of multicore particles: (I) MNCs fused in a random compact cluster, and (II) MNCs distributed on the surface of a large carrier sphere. The simulated magnetization data are then fitted using a common method based on a Langevin equation weighted with a size distribution function. Finally, the fitting parameters Dm and σm are compared to the real parameters Dp and σp used to generate the MNCs. Our results show that fitting magnetization data with a Langevin model that neglects magnetic anisotropy and dipole-dipole interactions leads to an erroneous estimate of the size distribution of the MNCs in multicore particles. The magnitude of the error depends on the particle morphology, number of MNCs contained in the particle and magnetic properties of the MNCs.
|
|
| 42. |
- Schaller, Vincent, 1979, et al.
(författare)
-
Development of an electrowetting-based microfluidic platform for magnetic immunoassays
- 2009
-
Ingår i: 13th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2009; Jeju; South Korea; 1 November 2009 through 5 November 2009. - 9780979806421 ; , s. 85-87
-
Konferensbidrag (refereegranskat)abstract
- We report the transport of magnetic nanoparticles (MNPs) in suspension in a 2 μl de-ionized water droplet (DIWD) using ElectroWetting-On-Dielectic (EWOD) actuation, and the detection of the MNPs by magnetic AC-susceptibility measurements using a highly sensitive high-Tc dc Superconducting Quantum Interference Device (SQUID) gradiometer. These results constitute the first development step towards a MNP-based magnetic immunoassay platform with SQUID-readout and sample droplet handling.
|
|
| 43. |
|
|
| 44. |
- Schaller, Vincent, 1979, et al.
(författare)
-
Effective magnetic moment of magnetic multicore nanoparticles
- 2009
-
Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 80:9, s. 092406-
-
Tidskriftsartikel (refereegranskat)abstract
- We carry out Monte Carlo simulations to study the effective magnetic moment mu(eff) in the low-field region of magnetic multicore nanoparticles. Transmission electron microscopy and scanning electron microscopy images show that these particles contain a number of magnetic nanocrystals (MNCs) randomly packed in a single cluster of total volume V(tot). We illustrate how the initial magnetic susceptibility chi(0) of magnetic multicore nanoparticles can be straightforward derived from mu(eff) computed at zero magnetic field. We observe that dipolar interactions between MNCs and polydispersity of the MNCs contribute to increase and to decrease mu(eff)/V(tot), respectively, while magnetic anisotropy of the MNCs does not show any effect. In all three cases, mu(eff)/V(tot) can be described by a linear relation to (mu B/k(B)T)(2) that we analytically derived for low applied fields.
|
|
| 45. |
- Schaller, Vincent, 1979, et al.
(författare)
-
Monte Carlo simulation of magnetic multi-core nanoparticles
- 2009
-
Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853. ; 321:10, s. 1400-1403
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, a Monte Carlo simulation is carried out to evaluate the equilibrium magnetization of magnetic multi-core nanoparticles in a liquid and subjected to a static magnetic field. The particles contain a magnetic multi-core consisting of a cluster of magnetic single-domains of magnetite. We show that the magnetization of multi-core nanoparticles cannot be fully described by a Langevin model. Inter-domain dipolar interactions and domain magnetic anisotropy contribute to decrease the magnetization of the particles, whereas the single-domain size distribution yields an increase in magnetization. Also, we show that the interactions affect the effective magnetic moment of the multicore nanoparticles.
|
|
| 46. |
|
|
| 47. |
- Schaller, Vincent, 1979, et al.
(författare)
-
Motion of nanometer sized magnetic particles in a magnetic field gradient
- 2008
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 104:9, s. no:093918-
-
Tidskriftsartikel (refereegranskat)abstract
- Using magnetic particles with sizes in the nanometer range in biomedical magnetic separation has gained much interest recently due to their higher surface area to particle volume and lower sedimentation rates. In this paper, we report our both theoretical and experimental investigation of the motion of magnetic particles in a magnetic field gradient with particle sizes from 425 nm down to 50 nm. In the experimental measurements, we monitor the absorbance change of the sample volume as the particle concentration varies over time. We also implement a Brownian dynamics algorithm to investigate the influence of particle interactions during the separation and compare it to the experimental results for validation. The simulation agrees well with the measurements for particle sizes around 425 nm. Some discrepancies remain for smaller particle sizes, which may indicate that additional factors also influence the separation for the smaller size range. We observe that the separation process includes the formation of chainlike particle aggregates due to the magnetic dipole-dipole interactions between particles when subjected to an external magnetic field. We can also see that the hydrodynamic interaction between these chains contributes to reducing the separation time. In conclusion, we show that the formation of these particle aggregates, and to a less extent the hydrodynamic interactions between them contributes to significantly enhancing the particle separation process. © 2008 American Institute of Physics.
|
|
| 48. |
|
|
| 49. |
- Schaller, Vincent, 1979, et al.
(författare)
-
The effect of dipolar interactions in clusters of magnetic nanocrystals
- 2010
-
Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 200:SECTION 7
-
Konferensbidrag (refereegranskat)abstract
- Monte Carlo simulations are carried out to evaluate the effective magnetic moment µeff of clusters containing 100 magnetic nanocrystals (MNCs) in a low magnetic field. The true value of the initial magnetic susceptibility, i.e. x0=∂M/∂H at zero field, can be assesed from µeff. Resuslts show that the dipolar interaction contribute to reduce the efeective magnetic moment. Below a threshold value near the low-field region, clusters of MNCs with smaller diameters possess a larger effective magnetic moment per unit volume compared to clusters with larger MNCs. This is of particular interest for bio-sensing systems relying on the magnetic responce of magnetic multi-core nanoparticles in the low-field region.
|
|
| 50. |
|
|
