The micro-air-vehicle Golden Snitch and its figure-of-8 flapping

[[abstract]]Relaxing from the conventional regarding of the rigid flapping mechanism, in this review paper the author introduced flexible wing frames for micro-air-vehicles (MAVs) with the wing span of 20 cm at Tamkang University. The constructed flappingMAVGolden Snitch with a smallest body mass of 5.9 g created a successful 107 s flight record with a four-bar linkage driving mechanism in 2008. Augmented by the precision injection molding (PIM) manufacture, the almost polymer-made MAV with the modified driving mechanism increases the flight endurance up to 480 s in 2010. Via high speed photography, the author has ever found the wing-tip trajectory as an oblique figure-of-8 which composes the original up-and-down flapping and the induced coherent streamwise vibration while the wingbeat frequency being about 10-25 Hz. The time-averaged lift, thrust coefficients and the structure aging of MAVs have been investigated to mention the corresponding influence. This figure-of-8 was done by the aero-elastic interactive nature as well as the symmetry-breaking of a simple flapping system. The bifurcation (duality) phenomenon of the oblique figure-of-8 was shown. How the rigidity of the flexible wing frame influences the flapping appearance was also addressed qualitatively. The flexible MAVs exhibited the peculiar figure-of-8 away from the conventional domain of MAVs by the perspective of scaling laws. Some remaining technical issues or future works of the figure-of-8 flapping were summarized finally.[[notice]]補正完畢[[journaltype]]國內[[incitationindex]]EI[[ispeerreviewed]]Y[[booktype]]紙本[[countrycodes]]TW

The Micro Patterning of Glutaraldehyde (GA)-Crosslinked Gelatin And Its Application To Cell-Culture

[[abstract]]This paper proposes a novel technique for fabricating micro patterns of glutaraldehyde (GA)-crosslinked gelatin. It provides another means to crosslink gelatin other than using photo-sensitizing agents, and the micro patterns of GA-crosslinked gelatin can still be made successfully by accessing conventional photolithography. A much less toxic and increased biocompatible approach to strengthening the gelatin microstructures can be developed according to this idea. This paper also describes a potential methodology for using GA-crosslinked gelatin patterns as single-cell culture bases. The best spatial resolution of the micro gelatin bases can reach 10 µm, and the selective growing density of human Mesenchymal stem cells on the gelatin patterns surpasses the density on the glass substrate by 2–3 orders of magnitude.[[incitationindex]]SCI[[booktype]]電子

Dynamic Attachment of HepG2 in Fractal Microchannels

[[abstract]]Dynamic filling experiments using HepG2 tumor cells are performed for observing the attachment behavior novelly in fractal microchannels. A PDMS microchannel mimicking the capillary blood vessel with fractal configuration is fabricated by the gelatin salt-out technique and the PDMS soft lithography. The fabrication of this low-toxicity fractal PDMS microchannel is firstly addressed herein. Using this PDMS microchannel, PBS with living HepG2 tumor cells are filled through. The cell attachment areas in the PDMS microchannel have been recorded dynamically with 10 min interval continuously for 2 hours. The result show that 2 hour is not enough for the permanent cell attachment of HepG2 in this fractal PDMS microchannel.[[sponsorship]]IEEE[[notice]]補正完畢[[conferencetype]]國際[[conferencedate]]20140416~20140416[[booktype]]紙本[[iscallforpapers]]Y[[conferencelocation]]Hawaii, US

SU-8 buckled-type microvalves switched by surface tension forces

[[abstract]]This paper presents the design, the fabrication, and the measurement result of a novel buckled-type microvalve. This device comprises of a parylene microtube for liquid transportation and a peacock-like SU-8 capillary microstructure for switching the microvalve without external power source. The maximal spreading angles of the peacock-like structures actuated by water surface tension are experimentally tested as 204deg and 15deg for the cases of not integrating and integrating a parylene microtube, respectively.[[incitationindex]]EI[[conferencetype]]國際[[conferencedate]]20070116~20070119[[conferencelocation]]Bangkok, Thailan

2D quasi-steady flow simulation of an actual flapping wing

[[abstract]]This paper deals about the dynamic behavior of flapping wing with an aid of stereo photography measurement using charge coupled device (CCD) camera. The three dimensional (3D) flapping motion was captured and coordinates are measured with the specific markers on the wing. The curved surface fitting was obtained from the 3D discrete coordinates using SURFER software. Consequently, a two dimensional (2D) cross section of flapping motion of the wing surface is sliced from 3D mesh. It was used further for the quasi-steady state computational fluid dynamics (CFD) simulation in Fluent. Utilizing two adjacent 2D trajectories, the upwind direction of flow filed was computed in this study. The computed dynamic velocity was considered to be input for the CFD analysis. The velocity and pressure distribution due to quasi-steady state flapping motion is observed in Fluent. The unsteady lift coefficient was obtained which was compared with experimental results from the wind tunnel. It was observed that, both theoretical and experimental results shows similar trend to validate the assumptions considered in the study.[[notice]]補正完畢[[journaltype]]國外[[ispeerreviewed]]Y[[booktype]]電子版[[countrycodes]]KO

Smart flapping wings with a PVDF sensor to modify aerodynamic performance of a micro UAV

[[abstract]]This paper describes a new configuration of flapping wings to study the aerodynamic behavior of a microUAV (unmanned aerial vehicle). The flapping wings are composed of a pure parylene right wing and a PVDF-parylene composite left wing on purpose. The PVDF (polyvinylidene fluoride) sensor could only export the lift signals from the left wing. In comparison to the total lift signal picked by the load cell from the wind-tunnel facility, we can figure out and separate the lift contributions donated by left wing and right wing, respectively. Therefore, we found a new design methodology to adjust the aerodynamic performance of microUAVs by changing the phase lag between the two flapping wings through fine tuning the mechanism linkages.[[incitationindex]]EI[[conferencetype]]國際[[conferencedate]]20070610~20070614[[conferencelocation]]Lyon, Franc

Photo-patternable gelatin as protection layers in surface micromachinings

[[abstract]]This paper describes a newly developed low-temperature photo-patternable Gelatin technology that is useful to produce a thick (greater than 10 microns) Gelatin protecting and strengthening layer for weak MEMS micro-structures. Example demonstrated here is the Gelatin process integrated with the Parylene MEMS technology. What is reported here is the complete processing details and formulae that allow anyone to use Gelatin like photo-resist. We find that it is a chemical-resistant and mechanical-robust material for MEMS applications.[[conferencetype]]國際[[conferencedate]]20020120~20020124[[booktype]]紙本[[conferencelocation]]Las Vegas, NV, US

The marching velocity of the capillary meniscus in a microchannel

In this paper we describe an experimental method and an analytical model for characterizing the surface energy inside a microchannel of micrometer size by measuring the marching velocity or position of a capillary meniscus. This method is based on the fact that the force summation of the meniscus surface tension and the filling reservoir gravitation might produce a pressure to pull liquid into the channel, and the marching velocity or the instantaneous position of the meniscus is related to the surface energy. Both parylene and silicon-nitride microchannels with different surface conditions were fabricated to perform the fill-in experiments subject to different liquids. It is shown that our model agrees well with the experimental data and is a valid method

Soap film visualization of a 10 cm-span flapping wing

[[abstract]]Flapping wing micro-air-vehicles (FWMAVs) animate the small-space dexterous flight, hovering, and energy-saving characteristics of birds and insects, and are believed to have enlightenment for the development of bionic flight in the future. When designing FWMAVs, detailed unsteady aerodynamic information is required. Besides the computational fluid mechanics (CFD) technology study, the flow visualization is also needed to assist this research. This article innovatively used soap film visualization with high-speed photography to record two kinds of the 2D flow fields laterally and longitudinally, respectively, generated by a flapping wing of 10 cm span. Different from the qualitative comparison of soap film imaging with the conventional smoke tracing method, the subsequent processing of the soap film images was demonstrated. This work explains how to quantify the soap film imaging into lift and thrust forces, and the corresponding results are compared with the wind tunnel force measurement data preliminarily.[[sponsorship]]MOST[[notice]]補正完

Design and numerical simulation of biomimetic structures to capture particles in a microchannel

[[abstract]]The study of separating different sizes of particles through a microchannel has been an interest in recent years and the primary attention of this study is to isolate the particles to the specific outlets. The present work highly focuses on the design and numerical analysis of a microchip and the microparticles capture using special structures like corrugated dragonfly wing structure and cilia walls. The special biomimetic structured corrugated wing is taken from the cross-sectional area of the dragonfly wing and cilia structure is obtained from the epithelium terminal bronchioles to the larynx from the human body. Parametric studies were conducted on different sizes of microchip scaled and tested up in the range between 2–6 mm and the thickness was assigned as 80 µm in both dragonfly wing structure and cilia walls. The microflow channel is a low Reynolds number regime and with the help of the special structures, the flow inside the microchannel is pinched and a sinusoidal waveform pattern is observed. The pinched flow with sinusoidal waveform carries the particles downstream and induces the particles trapped in desired outlets. Fluid particle interaction (FPI) with a time-dependent solver in COMSOL Multiphysics was used to carry out the numerical study. Two particle sizes of 5 µm and 20 µm were applied, the inlet velocity of 0.52 m/s with an inflow angle of 50° was used throughout the study and it suggested that: the microchannel length of 3 mm with corrugated dragonfly wing structure had the maximum particle capture rate of 20 µm at the mainstream outlet. 80% capture rate for the microchannel length of 3 mm with corrugated dragonfly wing structure and 98% capture rate for the microchannel length of 2 mm with cilia wall structure were observed. Numerical simulation results showed that the cilia walled microchip is superior to the corrugated wing structure as the mainstream outlet can conduct most of the 20 µm particles. At the same time, the secondary outlet can laterally capture most of the 5 µm particles. This biomimetic microchip design is expected to be implemented using the PDMS MEMS process in the future.[[sponsorship]]MOST[[notice]]補正完