| 1. |
- Delsing, Per, 1959, et al.
(författare)
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The 2019 surface acoustic waves roadmap
- 2019
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Ingår i: Journal of Physics D: Applied Physics. - : IOP Publishing. - 1361-6463 .- 0022-3727. ; 52:35
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Forskningsöversikt (refereegranskat)abstract
- Today, surface acoustic waves (SAWs) and bulk acoustic waves are already two of the very few phononic technologies of industrial relevance and can been found in a myriad of devices employing these nanoscale earthquakes on a chip. Acoustic radio frequency filters, for instance, are integral parts of wireless devices. SAWs in particular find applications in life sciences and microfluidics for sensing and mixing of tiny amounts of liquids. In addition to this continuously growing number of applications, SAWs are ideally suited to probe and control elementary excitations in condensed matter at the limit of single quantum excitations. Even collective excitations, classical or quantum are nowadays coherently interfaced by SAWs. This wide, highly diverse, interdisciplinary and continuously expanding spectrum literally unites advanced sensing and manipulation applications. Remarkably, SAW technology is inherently multiscale and spans from single atomic or nanoscopic units up even to the millimeter scale. The aim of this Roadmap is to present a snapshot of the present state of surface acoustic wave science and technology in 2019 and provide an opinion on the challenges and opportunities that the future holds from a group of renown experts, covering the interdisciplinary key areas, ranging from fundamental quantum effects to practical applications of acoustic devices in life science.
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| 2. |
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| 3. |
- Malmelöv, Andreas, et al.
(författare)
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Numerical modeling and synchrotron diffraction measurements of residual stresses in laser powder bed fusion manufactured alloy 625
- 2022
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Ingår i: Materials & design. - : Elsevier. - 0264-1275 .- 1873-4197. ; 216
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Tidskriftsartikel (refereegranskat)abstract
- Residual stresses in metal additive manufactured components are a well-known problem. It causes distortion of the samples when removing them from the build plate, as well as acting detrimental with regard to fatigue. The understanding of how residual stresses in a printed sample are affected by process parameters is crucial to allow manufacturers to tune their process parameters, or the design of their component, to limit the negative influence of residual stresses. In this paper, residual stresses in additive manufactured samples are simulated using a thermo-mechanical finite element model. The elasto-plastic behavior of the material is described by a mechanism-based material model that accounts for microstructural and relaxation effects. The heat source in the finite element model is calibrated by fitting the model to experimental data. The residual stress field from the finite element model is compared with experimental results attained from synchrotron X-ray diffraction measurements. The results from the model and measurement give the same trend in the residual stress field. In addition, it is shown that there is no significant difference in trend and magnitude of the resulting residual stresses for an alternation in laser power and scanning speed.
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| 4. |
- Ohlin, Mathias, et al.
(författare)
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Influence of acoustic streaming on ultrasonic particle manipulation in a 100-well ring-transducer microplate
- 2013
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Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 23:3, s. 035008-
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Tidskriftsartikel (refereegranskat)abstract
- We characterize and quantify the performance of ultrasonic particle aggregation and positioning in a 100-well microplate. We analyze the result when operating a planar ultrasonic ring transducer at different single actuation frequencies in the range 2.20-2.40 MHz, and compare with the result obtained from different schemes of frequency-modulated actuation. Compared to our previously used wedge transducer design, the ring transducer has a larger contact area facing the microplate, resulting in lower temperature increase for a given actuation voltage. Furthermore, we analyze the dynamics of acoustic streaming occurring simultaneously with the particle trapping in the wells of the microplate, and we define an adaptive ultrasonic actuation scheme for optimizing both efficiency and robustness of the method. The device is designed as a tool for ultrasound-mediated cell aggregation and positioning. This is a method for high-resolution optical characterization of time-dependent cellular processes at the level of single cells. In this paper, we demonstrate how to operate our device in order to optimize the scanning time of 3D confocal microscopy with the aim to perform high-resolution time-lapse imaging of cells or cell-cell interactions in a highly parallel manner.
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| 6. |
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| 7. |
- Guldevall, Karolin, et al.
(författare)
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Imaging Immune Surveillance of Individual Natural Killer Cells Confined in Microwell Arrays
- 2010
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 5:11, s. e15453-
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Tidskriftsartikel (refereegranskat)abstract
- New markers are constantly emerging that identify smaller and smaller subpopulations of immune cells. However, there is a growing awareness that even within very small populations, there is a marked functional heterogeneity and that measurements at the population level only gives an average estimate of the behaviour of that pool of cells. New techniques to analyze single immune cells over time are needed to overcome this limitation. For that purpose, we have designed and evaluated microwell array systems made from two materials, polydimethylsiloxane (PDMS) and silicon, for high-resolution imaging of individual natural killer (NK) cell responses. Both materials were suitable for short-term studies (<4 hours) but only silicon wells allowed long-term studies (several days). Time-lapse imaging of NK cell cytotoxicity in these microwell arrays revealed that roughly 30% of the target cells died much more rapidly than the rest upon NK cell encounter. This unexpected heterogeneity may reflect either separate mechanisms of killing or different killing efficiency by individual NK cells. Furthermore, we show that high-resolution imaging of inhibitory synapse formation, defined by clustering of MHC class I at the interface between NK and target cells, is possible in these microwells. We conclude that live cell imaging of NK-target cell interactions in multi-well microstructures are possible. The technique enables novel types of assays and allow data collection at a level of resolution not previously obtained. Furthermore, due to the large number of wells that can be simultaneously imaged, new statistical information is obtained that will lead to a better understanding of the function and regulation of the immune system at the single cell level.
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| 8. |
- Hultström, Jessica, et al.
(författare)
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Proliferation and viability of adherent cells manipulated by standing-wave ultrasound in a microfluidic chip
- 2007
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Ingår i: Ultrasound in Medicine and Biology. - : Elsevier BV. - 0301-5629 .- 1879-291X. ; 33, s. 145-151
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Tidskriftsartikel (refereegranskat)abstract
- Ultrasonic-standing-wave (USW) technology has potential to become a standard method for gentle and contactless cell handling in microfluidic chips. We investigate the viability of adherent cells exposed to USWs by studying the proliferation rate of recultured cells following ultrasonic trapping and aggregation of low cell numbers in a microfluidic chip. The cells form 2-D aggregates inside the chip and the aggregates are held against a continuous flow of cell culture medium perpendicular to the propagation direction of the standing wave. No deviations in the doubling time from expected values (24 to 48 h) were observed for COS-7 cells held in the trap at acoustic pressure amplitudes up to 0.85 MPa and for times ranging between 30 and 75 min. Thus, the results demonstrate the potential of ultrasonic standing waves as a tool for gentle manipulation of low cell numbers in microfluidic systems.
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| 9. |
- Iranmanesh, Ida, et al.
(författare)
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Acoustic micro-vortexing of fluids, particles and cells in disposable microfluidic chips
- 2016
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Ingår i: Biomedical microdevices (Print). - : Springer. - 1387-2176 .- 1572-8781. ; 18:4
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate an acoustic platform for microvortexing in disposable polymer microfluidic chips with small-volume (20 mu l) reaction chambers. The described method is demonstrated for a variety of standard vortexing functions, including mixing of fluids, re-suspension of a pellet of magnetic beads collected by a magnet placed on the chip, and lysis of cells for DNA extraction. The device is based on a modified Langevin-type ultrasonic transducer with an exponential horn for efficient coupling into the microfluidic chip, which is actuated by a low-cost fixed-frequency electronic driver board. The transducer is optimized by numerical modelling, and different demonstrated vortexing functions are realized by actuating the transducer for varying times; from fractions of a second for fluid mixing, to half a minute for cell lysis and DNA extraction. The platform can be operated during 1 min below physiological temperatures with the help of a PC fan, a Peltier element and an aluminum heat sink acting as the chip holder. As a proof of principle for sample preparation applications, we demonstrate on-chip cell lysis and DNA extraction within 25 s. The method is of interest for automating and chip-integrating sample preparation procedures in various biological assays.
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| 10. |
- Johansson, Linda, et al.
(författare)
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Surface acoustic wave-induced precise particle manipulation in a trapezoidal glass microfluidic channel
- 2012
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Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 22:2, s. 025018-
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Tidskriftsartikel (refereegranskat)abstract
- Surface acoustic wave (SAW) excitation of an acoustic field in a trapezoidal glass microfluidic channel for particle manipulation in continuous flow has been demonstrated. A unidirectional interdigital transducer (IDT) on a Y-cut Z-propagation lithium niobate (LiNbO3) substrate was used to excite a surface acoustic wave at approximately 35 MHz. An SU8 layer was used for adhesive bonding of the superstrate glass layer and the substrate piezoelectric layer. This work extends the use of SAWs for acoustic manipulation to also include glass channels in addition to prior work with mainly poly-di-methyl-siloxane channels. Efficient alignment of 1.9 mu m polystyrene particles to narrow nodal regions was successfully demonstrated. In addition, particle alignment with only one IDT active was realized. A finite element method simulation was used to visualize the acoustic field generated in the channel and the possibility of 2D alignment into small nodal regions was demonstrated.
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