-
[show abstract]
[hide abstract]
ABSTRACT: The field of microfluidics has drastically contributed to downscale the size of bench-top experiments to the dimensions of a chip without compromising. However, further miniaturization and the ability to directly manipulate individual molecules require a platform that permits organized molecular transport. The motor proteins and microtubules that carry out orderly intracellular transport are ideal for driving in vitro nanotransport. Here, we demonstrate that reconstructing the cellular kinesin/dynein-microtubule system in nanotracks provides a molecular total analysis system (MTAS) to control massively parallel chemical reactions. The mobility of kinesin and a microtubule dissociation method enable orientation of microtubule in an array for directed transport of reactive molecules carried by kinesin or dynein. Binding of glutathione S-transferase (GST) to glutathione (GSH), and of streptavidin to biotin, are visualized as colocalizations of quantum dots (Q-dots) when motor motilities bring them into contact. The organized nanotransport demonstrated here suggests the feasibility of using our platform to perform parallel biochemical reactions focusing at molecular level.
ACS Nano 12/2012; · 10.77 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A microfluidic device integrated with a Total Internal Reflection (TIR)-based chip for cell observation and analysis was developed. This integrated device enables in situ Total Internal Reflection Fluorescence Microscopy (TIRFM) on adherent cells cultured under continuous medium perfusion. This TIR-based chip, allows TIRFM to be easily performed on cells without the assembly of complicated optical components and cell culture chambers. The integrated device was evaluated by tracking the movement of fluorescent beads and monitoring the location of insulin granules in mouse pancreatic β-cells. This system offers higher signal-to-noise (S/N) ratio than epi-fluorescence microscopy (EPIFM), and comparable image quality to commercial TIRFM systems when imaging insulin granules. We also detected repetitive changes in intracellular Ca(2+) concentration in MIN6-m9 cells stimulated with KCl, which demonstrates quick perfusion for cell analysis while maintaining high S/N ratio.
Biomedical Microdevices 05/2012; 14(4):791-7. · 3.03 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This paper reports on piezoelectric micro-electro-mechanical systems deformable mirrors with high-density actuator array for
low-voltage and high-resolution retinal imaging with adaptive optics. The deformable mirror was composed of unimorph structure
of lead zirconate titanate (PZT) thin film deposited on Pt-coated silicon on insulator substrate and a diaphragm of 10mm
in diameter formed by backside-etching the Si handle wafer. 61 hexagonal electrodes were laid out on the PZT thin film for
the high-density actuator array. In order to reduce the dead space for the lead lines between the electrodes and connecting
pads, a polyimide layer with through holes on the electrodes was patterned as an electrical insulator. To confirm the application
feasibility of the fabricated DMs, displacement profiles of the actuators were measured by a laser Doppler vibrometer. Independent
applications of voltages on individual actuators were confirmed.
Microsystem Technologies 04/2012; 17(5):931-935. · 0.93 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In-plane unstrained single-c-domain/single-crystal thin films of PZT-based ternary ferroelectric perovskite, ξPb(Mn,Nb)O3-(1 - ξ)PZT, were grown on SrRuO(3)/Pt/MgO substrates using magnetron sputtering followed by quenching. The sputtered unstrained thin films exhibit unique ferroelectric properties: high coercive field, Ec > 180 kV/cm, large remanent polarization, P(r) = 100 μC/cm(2), small relative dielectric constants, ε* = 100 to 150, high Curie temperature, Tc = ~600 °C, and bulk-like large transverse piezoelectric constants, e31,f = -12.0 C/m(2) for PZT(48/52) at ξ = 0.06. The unstrained thin films are an ideal structure to extract the bulk ferroelectric properties. Their micro-structures and ferroelectric properties are discussed in relation to the potential applications for piezoelectric MEMS.
IEEE transactions on ultrasonics, ferroelectrics, and frequency control 01/2012; 59(1):6-13. · 1.80 Impact Factor
-
Sensors and Actuators A Physical 01/2011; · 1.80 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: (K(x),Na(1-x))NbO(3) (KNN) thin films were deposited on (001)SrRuO(3)/(001)Pt/(001)MgO substrates by RF-magnetron sputtering, and their piezoelectric properties were investigated. The x-ray diffraction measurements indicated that the KNN thin films were epitaxially grown with the c-axis orientation in the perovskite tetragonal system. The lattice constant of the c-axis increased with increasing concentrations of potassium. The KNN thin films showed typical ferroelectric behavior; the relative dielectric constant epsilon(r) was 270 to approximately 320. The piezoelectric properties were measured from the tip displacement of the KNN/MgO unimorph cantilevers; the transverse piezoelectric coefficient epsilon*(31) (= d(31)/s(E)(11)) of KNN (x = 0) thin films was calculated to be -0.9 C/m(2). On the other hand, doping of potassium caused an increase in the piezoelectric properties, and the KNN (x = 0.16) films showed a relatively large transverse piezoelectricity of epsilon*(31) = -2.4 C/m(2).
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control 01/2008; 54(12):2562-6. · 1.69 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Sodium niobate (NaNbO3, NN) thin films were deposited on
(001)SrRuO3/Pt/MgO substrates by rf magnetron sputter
deposition. The X-ray diffraction (XRD) pattern of the sputtered NN thin
films showed epitaxial growth with a (001)-oriented perovskite
structure. From the reciprocal space maps, the lattice parameters of the
in-plane and out-of-plane directions were a=0.392 nm and c=0.395 nm,
respectively. The relative dielectric constant \varepsilonr
and the range of the dielectric loss \tanδ were about 270 and
0.05-0.13 at 1 kHz, respectively. The P-E hysteresis loop showed clear
ferroelectricity with spontaneous polarization Ps of 20
μC/cm2 and coercive electric field Ec of 50
kV/cm. The transverse piezoelectric properties were evaluated from the
tip displacement of NN/MgO unimorph cantilevers. The transverse
piezoelectric coefficient e31*
(=d31/s11E) was -0.9 C/m2,
which is almost compatible with that of the bulk NN ceramics. The tip
deflection showed typical butterfly curves owing to the polarization
reversal, indicating that the sputtered NN thin films had a high
piezoelectric performance.
Japanese Journal of Applied Physics 09/2007; 46:6960. · 1.06 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Since most of miniaturized surface plasmon resonance (SPR) sensing systems need commercially available peristaltic or syringe
pumps, it is difficult to reduce the system size, biosample volume, and the production cost. In this paper, a compact biochip
for clinical diagnosis is presented. The proposed biochip is integrated traveling wave micropumps and SPR imaging sensors
on one chip. The micropump is composed of flexible microchannel and piezoelectric bimorph actuator array, and achieved the
maximum flow rate 336μl/min. The SPR imaging biosensor can quantitatively measure biosamples with multi microchannels, i.e.
one biosample and two reference flows to obtain an analytical curve. The SPR imaging measurements with bovine serum albumin
solutions were carried out using the prototype of the proposed diagnostic system composed of a pair of the micropump and the
sensor. Since the clear SPR signal curve was observed, it was confirmed that the proposed system can be applicable to the
clinical diagnosis.
Microsystem Technologies 04/2007; 13(8):1391-1396. · 0.93 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In this paper, we propose a cell encapsulation and hydrogel-beads production method using droplet formation in a microchannel.
The hydrogel-beads produced by the microfluidic device developed here have smaller diameter and narrower distribution in their
diameter compared to the conventional method, such as the droplet extrusion and the emulsification. The effects of the flow
velocity and microchannel wall were analyzed based on fluid dynamical analysis. The results revealed that the wall effect
of the microchannel strongly affected to the diameter of the droplet and the shape of the hydrogel-beads.
Microsystem Technologies 01/2007; 13(8):951-958. · 0.93 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In this study, we report piezoelectric microactuators composed of Pb(Zr,Ti)O3 (PZT) films for low-voltage RF-MEMS switches. In order to realize a flat beam shape as well as a large displacement, we have
adopted an X-shaped connector at the center of the beam. Finite element method (FEM) simulation indicates that the bending
motion of the beam is almost same as two connected cantilevers, and the maximum displacement reaches 3.2μm/5V. To fabricate
the microactuators, piezoelectric PZT films were deposited on Si substrates using rf-sputtering and microfabricated into the
PZT/Cr unimorph actuators of 800μm in length and 200μm in width, respectively. Although the X-shaped connector effectively
releases the stress of the multilayered beam so that the beam shape is almost flat, small residual stress caused slight concave
curvature along the width. The displacement at the center of the beam was measured using a laser Doppler vibrometer. The measurement
revealed that the displacement was 0.5μm/5V which was lower than the FEM result. The reduction of the displacement is attributed
to the increase of the stiffness of the beam due to the concave curvature of the beam width.
Microsystem Technologies 01/2007; 13(8):825-829. · 0.93 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This paper presents a polymer-based micropump addressing the cost, performance, and system compatibility issues that have limited the integration of on-chip micropumps into microanalysis systems. This pump uses dielectric elastomer actuation to periodically displace fluid, and a pair of elastomeric check valves to rectify the fluid's resulting movement. Its significant features include the use of a transparent substrate, self-priming capability, insensitivity to gas bubbles, and the ability to admit particles. A pump occupying less than 10 mm2 of chip space produced a 77 microl min(-1) flow rate. The pump has a high thermodynamic efficiency and exhibits little performance degradation over 10 hours of operation. In addition to its notable performance, the pump can be fabricated at low cost and directly integrated into microfluidic chips that use planar softlithography-formed structures. The new pump concept, fabrication, and experimental performance are discussed herein.
Lab on a Chip 10/2006; 6(9):1147-54. · 5.67 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Single-crystal lead titanate [(001)PbTiO3 (PT)] thin films were heteroepitaxially grown on a miscut strontium titanate [(001)SrTiO3 (ST)] substrate by radio frequency magnetron sputtering. The PT thin films were grown via a step-flow growth. The step-flow growth enhanced the layer growth resulting in the continuous (001) single-crystal structure without a dislocated interface for the film thickness below 200 to 250 nm. The PT thin films show a small temperature variation of the lattice parameters unlikely to the bulk PT crystals due to the substrate clamping. The temperature variation of the lattice constants is discussed in terms of the thermo-elastic deformation analysis for the PT/ST heterostructure.
Journal of Materials Research. 04/2006; 21(05):1261 - 1268.
-
Journal of Materials Research 01/2006; · 1.43 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We performed structural studies on PZT thin films, Pby(Zr0.57Ti0.43)2-yO3; y=0.97, 1.07, 1.15. The thin films were deposited on Pt (001)/MgO (001) substrates by rf-magnetron sputtering. Every film grew epitaxially in a tetragonal phase with the “cube on cube” relationship to the substrate, and contained no other crystalline phases, such as PbO or pyrochlore. It is known that PZT bulk ceramic with Zr/Ti of about 57/43, the composition of which is on the Zr-rich side of the morphotropic phase boundary (MPB), has a rhombohedral structure at room temperature. These PZT films, however, had tetragonal perovskite structures (space group: P4mm). The Pb atoms mainly occupy the A (1a) site, and the Zr and Ti atoms occupy the B (1b) site at random. When y is less than unity in Pby(Zr0.57Ti0.43)2-yO3, the excess Zr/Ti tends to enter the Pb (A) sites and randomly occupy the sites together with Pb; and when y is more than unity, the excess Pb tends to mix with the Zr and Ti at Zr/Ti (B) sites. In all these films, the atomic positions of Zr/Ti, O(1), and O(2) shift mutually along the c axis in the tetragonal structure. With increasing y, c/a approaches unity and the crystal structure shifts toward the rhombohedral phase, especially in the O(2) atomic position, where a large shift was observed. The PZT thin films were grown under the restraint of a Pt (001) square lattice, and under isotropic compressive plane stress. These are the major reasons that the film crystallizes into tetragonal perovskite and polarizes spontaneously in the c-axis direction perpendicular to the substrate surface.
Phys. Rev. B. 08/2002; 66(6).
-
Integrated Ferroelectrics 09/1998; 21(1-4):451-460. · 0.30 Impact Factor
-
-
-
[show abstract]
[hide abstract]
ABSTRACT: Piezoelectric Pb(Zr, Ti)O3 (PZT) thin films were directly deposited on cantilever-shaped titanium substrates and evaluated for their piezoelectric properties and actuator performance. Because of the small difference in the thermal expansion coefficient between the PZT and the substrate, and the mitigation of the residual stress, large piezoelectric properties could be obtained for PZT/Ti unimorph actuators. X-ray diffraction measurements clearly revealed that the PZT thin films have a polycrystalline perovskite structure with a random orientation. Observations using a scanning electron microscope (SEM) demonstrated that PZT films, which were 3.8 mum thick, were densely deposited on Pt-coated Ti substrate without pores or cracks. The polarization-electric field (P- E) hysteresis of the PZT film clearly indicates ferroelectricity. The piezoelectric properties of the PZT films were evaluated from the tip displacement of PZT/Ti unimorph cantilevers. Simplified transverse piezoelectric coefficients (e31 * = d31/s11 E, where d31 and s11 E are piezoelectric coefficient and elastic compliance, respectively) were measured, which ranged from -3.6 to 4.3 C/m2 - about three times larger than those of the PZT thin films deposited on stainless-steel substrates. Measurement of resonant frequencies of the cantilevers shows a clear dependence on the cantilever length, which obeys the theoretical equation. This indicates that these cantilevers can be reliably applied as sensors and actuators in a resonance mode.
-
[show abstract]
[hide abstract]
ABSTRACT: Piezoelectric Pb(Zr,Ti)O3 (PZT) thin films with a composition near the morphotoropic phase boundary were deposited directly on cantilever-shaped stainless steel (SUS) substrates using RF-magnetron sputtering for application of micro-electromechanical systems (MEMS). X-ray diffraction measurements reveal that the PZT thin films have a polycrystalline perovskite structure with a preferential orientation of (1 0 1). Cross-section morphology – observed using a scanning electron microscope – indicates that the PZT films exhibit a dense columnar structure without pores or clacks. The films’ P–E hysteresis loops indicate clear ferroelectricity. Based on the deflection characteristics of the cantilever, the effective piezoelectric coefficient e31 of the PZT films is measured to be −1.35 C/m2.
Sensors and Actuators A: Physical.
-
