Yoshihide Makino

Improved Designs for an Electrothermal In-Plane Microactuator

Reported presently are two design approaches to improve the performance of an electrothermal in-plane microactuator with “chevron” beams. One incorporates beams with uniform cross sections but nonuniform lengths or tilt angles to accommodate the thermally induced expansion of the “shuttle”; the other incorporates beams with nonuniform cross sections to widen the high-temperature “expansion” zones. It is derived analytically, verified using finite-element simulations, and tested by microfabricating actuators occupying a constrained device area that the incorporation of one or the other proposed features leads to an improved performance figure-of-merit, defined to be the product of the actuation displacement and force. An increase in the figure-of-merit by up to 65% per beam has been measured.

Phenotypic and transcriptional modulation of human pluripotent stem cells induced by nano/microfabrication materials.

Gelatin + N.D N.D Human pluripotent stem cells (hPSCs) including embryonic stem (hES) [ 1 ] and induced pluripotent stem (hiPS) [ 2–5 ] cells have signifi cant potential for applications in cell-based therapy, regenerative medicine, and drug development/screening because of their unique characteristics. hPSCs can self-renew without limit when cultured in vitro without any karyotypical abnormalities and can differentiate into any type of human cell. To control hPSC functions such as lineage-specifi c differentiation, self-renewal, migration, and apoptosis, it is necessary to precisely regulate the extracellular microenvironments in vivo . These are important for controlling cellular functions both in vivo and in vitro. [ 6 ]

Negative-photoresist mechanical property for nano-filtration membrane embedded in microfluidics

We report on a simple UV photolithography based fabrication for an epoxy-based filtration membrane and its primary features such as the permeability and the elastic modulus toward a design of polymer-based microfluidic systems. The elastic modulus of filtration membrane was measured by an indentation test, and then which was evaluated by a cross-linked ratio of epoxy group to clarify the dependence on the process parameters. It was revealed for the first time that the elastic modulus for filtration membrane varied from 3.8 GPa to 4.9 GPa according to the cross-linked ratio of 0.5 to 0.75.

Epoxy-based permeable membrane fabrication for 3D microfluidic device

We report for the first time on a simple fabrication via UV photolithography for a free-standing filtration membrane made of epoxy-based photoresist and its integration on a multilevel microfluidic device. The fabrication process involves three-dimensional thick-photoresist microstructuring combined with standard negative photoresist processing. In this paper, a primary feature of membrane permeability dependence on fabrication process parameters was characterized by employing a cross-linking reaction model. The experiments using a multilevel microfluidic device demonstrated the proposed fabrication is capable of fabricating nano-filtration membrane while maintaining a sufficient mechanical strength for applications in polymer-based microfluidic devices.

Designs for improving the performance of an electro-thermal in-plane actuator

Reported presently are two designs to improve the performance of a “chevron” electro-thermal in-plane actuator. One incorporates beams with uniform cross-sections but nonuniform lengths and tilt angles to accommodate the thermally induced expansion of the “shuttle”; the other incorporates beams with non-uniform cross-sections to achieve a wider spread of the high temperature “expansion” regions of the beams. With the product of the actuation force and displacement defined as a figure-of-merit, it is verified using finite-element simulation that the incorporation of non-uniform lengths and tilt angles, and non-uniform beam cross-sections leads to respective improvement of 10 and 65% in the figure-of-merit. The effectiveness of these designs was also tested by micro-fabricating actuators occupying fixed device areas.