ORCID Profile
0000-0002-0298-5558
Current Organisation
Keio University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Elsevier BV
Date: 06-2010
Publisher: Elsevier BV
Date: 06-2009
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C6LC01310D
Abstract: Cell agglomeration is essential both to the success of drug testing and to the development of tissue engineering. Here, a MHz-order acoustic wave is used to generate acoustic streaming in the wells of a 24-well plate to drive particle and cell agglomeration. Acoustic streaming is known to manipulate particles in microfluidic devices, and even provide concentration in sessile droplets, but concentration of particles or cells in in idual wells has never been shown, principally due to the drag present along the periphery of the fluid in such a well. The agglomeration time for a range of particle sizes suggests that shear-induced migration plays an important role in the agglomeration process. Particles with a diameter of 45 μm agglomerated into a suspended pellet under exposure to 2.134 MHz acoustic waves at 1.5 W in 30 s. Additionally, BT-474 cells also agglomerated as adherent masses at the center bottom of the wells of tissue-culture treated 24-well plates. By switching to low cell binding 24-well plates, the BT-474 cells formed suspended agglomerations that appeared to be spheroids, fully fifteen times larger than any cell agglomerates without the acoustic streaming. In either case, the viability and proliferation of the cells were maintained despite acoustic irradiation and streaming. Intermittent excitation was effective in avoiding temperature excursions, consuming only 75 mW per well on average, presenting a convenient means to form fully three-dimensional cellular masses potentially useful for tissue, cancer, and drug research.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2016
Publisher: Wiley
Date: 27-02-2020
Publisher: Springer Science and Business Media LLC
Date: 21-05-2022
DOI: 10.1007/S10544-022-00617-Z
Abstract: Three-dimensional cell agglomerates are broadly useful in tissue engineering and drug testing. We report a well-free method to form large (1.4-mm) multicellular clusters using 100-MHz surface acoustic waves (SAW) without direct contact with the media or cells. A fluid couplant is used to transform the SAW into acoustic streaming in the cell-laden media held in a petri dish. The couplant transmits longitudinal sound waves, forming a Lamb wave in the petri dish that, in turn, produces longitudinal sound in the media. Due to recirculation, human embryonic kidney (HEK293) cells in the dish are carried to the center of the coupling location, forming a cluster in less than 10 min. A few minutes later, these clusters may then be translated and merged to form large agglomerations, and even repeatedly folded to produce a roughly spherical shape of over 1.4 mm in diameter for incubation—without damaging the existing intercellular bonds. Calcium ion signaling through these clusters and confocal images of multiprotein junctional complexes suggest a continuous tissue construct: intercellular communication. They may be formed at will, and the method is feasibly useful for formation of numerous agglomerates in a single petri dish.
Publisher: ASMEDC
Date: 2008
Abstract: There has been some amount of confusion over the origin of electrohydrodynamic phenomena responsible for the actuation of dielectric fluids in the presence of an electric field. Previous studies have accounted for the possibility of conduction pumping, ion drag pumping and induction pumping as driving mechanisms but have ignored the possibility of Maxwell (electric) pressure driven flow. Until recently, this mechanism has been poorly understood and as a result has often been overlooked. This paper demonstrates how a Maxwell pressure gradient can induce flow in dielectric liquids in the presence of a non-uniform field. We derive, from first principles using lubrication theory, an expression for the flow velocity which exhibits a quadratic dependence on the applied voltage and also proportionality to the ratio of the permittivity and viscosity. The theoretical predictions are supported by experimental results. Although we have examined the phenomenon for a particular class of dielectric liquids, it is believed that this mechanism could well be responsible for the actuation of other low conductivity dielectric fluids previously attributed to conduction or ion drag pumping. In any case, we discuss ways to identify the dominant mechanism by comparing the salient features for a given type of flow.
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D0LC01293A
Abstract: After exposing a plated C2C12 cells culture to PBS, ultrasound from the SAW device transmitted into the cell culture via a coupling water droplet. We can remove cells from an area 6 × 10 −3 mm 2 , equivalent to about 12 cells.
No related grants have been discovered for Kenjiro Takemura.