| 1. |
- Iranmanesh, Ida, et al.
(författare)
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Magnitude and variance of acoustic energy density in microchannel acoustophoresis : Comparison between single-frequency and frequency-modulated actuation
- 2013
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Ingår i: 17th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2013. - 9781632666246 ; , s. 1400-1402
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Konferensbidrag (refereegranskat)abstract
- Using a novel light-intensity method, we quantify for the first time the magnitude and spatial variance in acoustic energy density along a microchannel during acoustophoretic focusing of particles with frequency-modulated ultrasound. We compare the distribution in energy density between single-frequency (SF) and frequency-modulation (FM) actuation along the microchannel. In addition, we analyze the field uniformity for the two actuation approaches (SF and FM) by measuring the deviation of the final particle pattern from an ideal straight line. We conclude that the magnitude of the energy density for FM actuation is of the same order of magnitude as for SF actuation, but with much less spatial variance.
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| 2. |
- Iranmanesh, Ida Sadat, et al.
(författare)
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Tunable-angle wedge transducer for improved acoustophoretic control in a microfluidic chip
- 2013
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Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 23:10, s. 105002-
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Tidskriftsartikel (refereegranskat)abstract
- We present a tunable-angle wedge ultrasound transducer for improved control of microparticle acoustophoresis in a microfluidic chip. The transducer is investigated by analyzing the pattern of aligned particles and induced acoustic energy density while varying the transducer geometry, transducer coupling angle, and transducer actuation method (single-frequency actuation or frequency-modulation actuation). The energy-density analysis is based on measuring the transmitted light intensity through a microfluidic channel filled with a suspension of 5 mu m diameter beads and the results with the tunable-angle transducer are compared with the results from actuation by a standard planar transducer in order to decouple the influence from change in coupling angle and change in transducer geometry. We find in this work that the transducer coupling angle is the more important parameter compared to the concomitant change in geometry and that the coupling angle may be used as an additional tuning parameter for improved acoustophoretic control with single-frequency actuation. Further, we find that frequency-modulation actuation is suitable for diminishing such tuning effects and that it is a robust method to produce uniform particle patterns with average acoustic energy densities comparable to those obtained using single-frequency actuation.
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| 3. |
- Muller, P. B., et al.
(författare)
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Ultrasound-induced acoustophoretic motion of microparticles in three dimensions
- 2013
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Ingår i: Physical Review E (Statistical, Nonlinear, and Soft Matter Physics). - 1539-3755. ; 88:2
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Tidskriftsartikel (refereegranskat)abstract
- We derive analytical expressions for the three-dimensional (3D) acoustophoretic motion of spherical microparticles in rectangular microchannels. The motion is generated by the acoustic radiation force and the acoustic streaming-induced drag force. In contrast to the classical theory of Rayleigh streaming in shallow, infinite, parallel-plate channels, our theory does include the effect of the microchannel sidewalls. The resulting predictions agree well with numerics and experimental measurements of the acoustophoretic motion of polystyrene spheres with nominal diameters of 0.537 and 5.33 mu m. The 3D particle motion was recorded using astigmatism particle tracking velocimetry under controlled thermal and acoustic conditions in a long, straight, rectangular microchannel actuated in one of its transverse standing ultrasound-wave resonance modes with one or two half-wavelengths. The acoustic energy density is calibrated in situ based on measurements of the radiation dominated motion of large 5-mu m-diameter particles, allowing for quantitative comparison between theoretical predictions and measurements of the streaming-induced motion of small 0.5-mu m-diameter particles.
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| 4. |
- Wu, CZ, et al.
(författare)
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The Potential of Nano-Porous Surface Structure for Pain Therapeutic Applications: Surface Properties and Evaluation of Pain Perception
- 2020
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Ingår i: APPLIED SCIENCES-BASEL. - : MDPI AG. - 2076-3417. ; 10:13
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The objective of this study was to evaluate the biomaterial properties of nano-modified surface acupuncture needles and the effect of such needles on human pain perception by using pressure pain threshold (PPT) measurements. It is known that changing a material’s surface nano-topography or nanostructure has strong effects on its physical, chemical, and biological surface properties. However, there is no information in the literature about the stimulation characteristics of acupuncture needles with nano-topography or nanostructured surfaces. Based on the knowledge on nanostructured surfaces, it may be possible to potentiate the effects of acupuncture needle stimulation. The pressure pain sensitivity of the masseter muscle in the orofacial region was studied in 21 healthy volunteers in two randomized, double-blinded sessions: an active session of manual acupuncture manipulation with nano-modified surface needles, and an inactive session of sham acupuncture stimulation to control for possible placebo effects. Three acupuncture points were selected from classical Chinese medicine literature: LI4 (Hegu) on the hand, ST6 (Jiache) on the lower masseter region, and ST7 (Xiaguan) on the upper masseter region. PPT measurements, perceived sensations, and pain from the acupuncture were recorded. The results showed discrete yet significant differences in PPT values between the active and inactive acupuncture treatments and significantly higher pain scores from active acupuncture stimulation than from sham acupuncture. These results indicate subtle but significant effects of acupuncture stimulation with nano-modified surface needles, compared to sham acupuncture in healthy participants.
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