Hiroaki Onoe

Ultrasound-triggered drug delivery has been widely researched for its potential to improve the therapeutic efficacy of drugs. This paper presents drug release using hydrogel microbeads with release enhancer for efficient ultrasound-triggered drug delivery. By using a centrifuge-based microfluidic device, drug-model-encapsulating calcium alginate hydrogel microbeads containing tungsten particles with high acoustic impedance were fabricated. Because the tungsten particles work as release enhancer,

This paper describes three-dimensional micro-self-assembly using hydrophobic interaction. The interaction between microparticles was controlled using self-assembled monolayers formed on the particles. The particles were stirred in a dispersion liquid to create a binding for connecting their surfaces directly. The interaction between the particles was described by the thermodynamic free energy of adhesion, which was calculated using the surface free energies of the solids and the liquid. The calc

We propose a method to print four-dimensional (4D) stimuli-responsive hydrogel structures with internal gaps. Our 4D structures are fabricated by printing an N-isopropylacrylamide-based stimuli-responsive pre-gel solution (NIPAM-based ink) and an acrylamide-based non-responsive pre-gel solution (AAM-based ink) in a supporting viscous liquid (carboxymethyl cellulose solution) and by polymerizing the printed structures using ultraviolet (UV) light irradiation. First, the printed ink position and w

Stimuli-responsive microfibers are fabricated by extruding mixed solutions of poly(N-isopropylacrylamide-co-acrylic acid) (pNIPAM-AAc) and sodium alginate (Na-alginate) using a microfluidic spinning system. The fabricated microfibers shrink and swell with temperature and/or pH. By controlling the extruded laminar flow, microfibers capable of anisotropic shrinkage are fabricated. Cross-sectional microscale geometries of microfibers, including double layering and hollowness, are successfully contr

Assembly line: Hydrophobic, repulsive double-layer, and van der Waals interactions have been employed in the sequential self-assembly of microfabricated silicon parts in aqueous solution. Control of the assembly sequence is realized by simply changing the pH of the solution. The fabrication of column- and barrel-shaped microstructures and closed-link microchain structures is demonstrated through a two-step self-assembly process (see picture). Supporting information for this article is available

We present an extracellular matrix (ECM)-based stretchable microfluidic system for culturing in vitro three-dimensional (3D) vascular tissues, which mimics in vivo blood vessels. Human umbilical vein endothelial cells (HUVECs) can be cultured under perfusion and stretch simultaneously with real-time imaging by our proposed system. Our ECM (transglutaminase (TG) cross-linked gelatin)-based microchannel was fabricated by dissolving water-soluble sacrificial polyvinyl alcohol (PVA) molds printed wi

This paper describes a new fabrication method for obtaining anisotropic spherical hydrogel microparticles with different types of extracellular matrix (ECM) hemispheres for use in 3D cell culture. To fabricate the microparticles, a mixture of an ECM precursor solution and sodium alginate is ejected into a calcium chloride solution under large centrifugal acceleration by a centrifuge-based microfluidic device; the calcium alginate hydrogel plays a significant role as a "sacrificial gelation templ

This paper describes a simple, rapid, and inexpensive method for cell encapsulation that uses a small amount (sub-microliter-scale) of cell-suspended pre-gel solution. This method requires only a glass capillary, an acrylic holder, and a tabletop centrifuge, and achieves cell encapsulation in calcium alginate microbeads using cell-suspended sub-microliter-volume pre-gel solution in 20 s. The method also ensures high cell encapsulation efficiency, with a sample loss of as low as several tens of n

In this paper, a tubular 3D microenvironment created in a calcium alginate hydrogel microtube with respect to the effect of scaffold dimensions on the differentiation of mouse neuronal stem cells (mNSCs) is evaluated. Five types of hydrogel microtubes with different core diameters (≈65-200 μm) and shell thicknesses (≈30-110 μm) are fabricated by using a double coaxial microfluidic device, and differentiation of encapsulated mNSCs is induced by changing the growth medium to the differentiation me

We propose a method of integrating heterogeneous silicon microstructures (typical scale of 10–100 µm) into a single silicon substrate to fabricate MEMS structures. It includes adhesion-based liftoff and stamping transfer (LIST) processes using poly-(dimethylsiloxane) (PDMS) sheets. Silicon microstructures fabricated on different wafers are lifted onto the PDMS sheets by breaking the narrow columns supporting the microstructures by applying a vertical load to the PDMS sheet, and then transferred

This paper describes a method for manipulating adherent cells using microfabricated mobile microplates. This method allows us to change the positions of the cells without detaching them from the plates. A variable number of adherent cells ranging from one to a few cells were patterned on microplates (50–75 µm in diameter and 2 µm in thickness) that were fixed to a poly(dimethylsiloxane) (PDMS) sheet. The cell-patterned microplates were released by physical means without the use of chemicals and

We propose a wireless pressure sensor composed of a graphene sheet and a transmitter coil integrated with a polydimethylsiloxane (PDMS) tube. The pressure inside the tube was monitored wirelessly using an external receiver coil. We then monitored the typical blood pressure range, 12⁻20 kPa, using this fabricated sensor by changing the turn number of the receiver coil and the overlapping length of the coils. Furthermore, we demonstrated wireless blood pressure measurement by connecting our sensor