9 research outputs found
A New Silicon Mold Process for Polydimethylsiloxane Microchannels
No full textAs an alternative to SU-8 soft lithography, a new silicon mold process of fabricating PDMS microchannel chips was proposed. A picosecond laser is used to cut through a 550 μm thick silicon wafer and generate the original microchannel pattern with a 50 μm minimum feature size. This single-crystal silicon pattern, with the edge debris caused by laser cutting being trimmed off by a KOH solution and with the protection field oxide layer being removed by BOE afterwards, firmly resided on a glass substrate through the anodic bonding technique. Four-inch wafers with microchannel patterns as the PDMS mold cores were successfully bonded on Pyrex 7740 or Eagle XG glass substrates for the follow-up PDMS molding/demolding process. This new maskless process does not need a photolithography facility, but the laser cutting service must be provided by professional off-campus companies. One PDMS microchannel chip for particle separation was shown as an example of what can be achieved when using this new process.國科會補正完畢CH
Fabrication, aerodynamic measurement and performance evaluation of corrugated flapping wings
No full textThis paper deals with the fabrication, aerodynamic measurement, and performance evaluation of the corrugated wing patterns on a flapping wing micro air vehicle (FWMAV). The corrugated wing pattern is generally seen in insects. Insect wings with their corrugated topological features give themselves high load-bearing capacity during flapping and hovering. It is believed that appropriate corrugated structures on insect wings enhance aerodynamic performance. A new fabrication process using polydimethylsiloxane (PDMS)-molding and parylene coating was proposed and implemented for a 24 cm-span FWMAV, which is composed of corrugated wing inspired by the dragonfly wing. The fabrication includes the master wing template made by three-dimensional (3D) printing, the PDMS molding process for wing template duplication, and the final parylene coating to obtain corrugated wings. The parylene-C thickness was selected as 40 μm. For comparing the aerodynamic performance, two types of flapping wings were implemented on the FWMAVs: first with a pair of parylene corrugated wings and the other with polyethylene terephthalate (PET) flat membrane (without corrugation) wings. The lift signal was then measured by the load cell in a wind tunnel. Regarding the aerodynamic performance of flapping wings, a systematic performance estimation of finding the cruising conditions and the cruising lift for FWMAVs was investigated through the massive wind tunnel data. The parylene flapping wings with corrugation attained lift coefficients of 7.8-8.0, which the PET flat membrane wing cannot achieve so far.補正完
A New Silicon Mold Process for Polydimethylsiloxane Microchannels
No full textAs an alternative to SU-8 soft lithography, a new silicon mold process of fabricating PDMS microchannel chips was proposed. A picosecond laser is used to cut through a 550 μm thick silicon wafer and generate the original microchannel pattern with a 50 μm minimum feature size. This single-crystal silicon pattern, with the edge debris caused by laser cutting being trimmed off by a KOH solution and with the protection field oxide layer being removed by BOE afterwards, firmly resided on a glass substrate through the anodic bonding technique. Four-inch wafers with microchannel patterns as the PDMS mold cores were successfully bonded on Pyrex 7740 or Eagle XG glass substrates for the follow-up PDMS molding/demolding process. This new maskless process does not need a photolithography facility, but the laser cutting service must be provided by professional off-campus companies. One PDMS microchannel chip for particle separation was shown as an example of what can be achieved when using this new process
Design and Numerical Simulation of Biomimetic Structures to Capture Particles in a Microchannel
No full textThe 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
An Enhanced Sampling-Based Viewpoints Cosine Visual Model for an Efficient Big Data Clustering
No full textBunching is registering the item's similitude includes that can be utilized to segment the information. Object similarity (or dissimilarity) features are taken into account when locating relevant data object clusters. Removing the quantity of bunch data for any information is known as the grouping inclination. Top enormous information bunching calculations, similar to single pass k-implies (spkm), k-implies ++, smaller than usual group k-implies (mbkm), are created in the groups with k worth. By and by, the k worth is alloted by one or the other client or with any outside impedance. Along these lines, it is feasible to get this worth immovable once in a while. In the wake of concentrating on related work, it is researched that visual appraisal of (bunch) propensity (Tank) and its high level visual models extraordinarily decide the obscure group propensity esteem k. Multi-perspectives based cosine measure Tank (MVCM-Tank) utilized the multi-perspectives to evaluate grouping inclination better. Be that as it may, the MVCM-Tank experiences versatility issues in regards to computational time and memory designation. This paper improves the MVCM-Tank with the inspecting methodology to defeat the versatility issue for large information grouping. Trial investigation is performed utilizing the enormous gaussian engineered datasets and large constant datasets to show the effectiveness of the proposed work
Mechanical, thermal and shape memory characterization of a novel epoxy shape memory polymer
No full textIn past 3 decades a large number of shape memory polymers are available for various applications. This paper is aimed to produce a novel epoxy polymer by combining an epoxy base polymer Diglycidyl Ether of Bisphenol-A (DGEBA-Araldite LY556) and Polypropylene Glycol Diglycidyl Ether (PPGDE). The mechanical, thermal and shape memory characterization of material is done. It was found that the tensile strength of the material is reduced linearly with increasing the percentage of PPGDE. The elongation at break of the material is increased from 10% to 60% with 25% addition of PPGDE. The glass transition temperature of the material decreases linearly with increasing PPGDE percentage. D-70-P-30 (DGEBA-PPGDE) combination of the material is chosen for shape memory characterisation as its glass transition is above and within the vicinity of room temperature which is the pre-requisite for cold programming. The material shows good shape memory properties such as shape fixity and shape recovery
Check-valve design in enhancing aerodynamic performance of flapping wings
No full textA flapping wing micro air vehicle (FWMAV) demands high lift and thrust generation for a desired payload. In view of this, the present work focuses on a novel way of enhancing the lift characteristics through integrating check-valves in the flapping wing membrane. Modal analysis and static analysis are performed to determine the natural frequency and deformation of the check-valve. Based on the inference, the check-valve opens and closes during the upstroke flapping and downstroke flapping, respectively. Wind tunnel experiments were conducted by considering the two cases of wing design, i.e., with and without a check-valve for various driving voltages, wind speeds and different inclined angles. A 20 cm-wingspan polyethylene terephthalate (PET) membrane wing with two check-valves, composed of central disc-cap with radius of 7.43 mm, supported by three S-beams, actuated by Evans mechanism to have 90° stroke angle, is considered for the 10 gf (gram force) FWMAV study. The aerodynamic performances, such as lift and net thrust for these two cases, are evaluated. The experimental result demonstrates that an average lift of 17 gf is generated for the case where check-valves are attached on the wing membrane to operate at 3.7 V input voltage, 30° inclined angle and 1.5 m/s wind speed. It is inferred that sufficient aerodynamic benefit with 68% of higher lift is attained for the wing membrane incorporated with check-valve.MOST補正完
ABHD11-AS1: An Emerging Long Non-Coding RNA (lncRNA) with Clinical Significance in Human Malignancies
No full textThe aberrant expression of lncRNAs has been linked to the development and progression of different cancers. One such lncRNA is ABHD11 antisense RNA 1 (ABHD11-AS1), which has recently gained attention for its significant role in human malignancies. ABHD11-AS1 is highly expressed in gastric, lung, breast, colorectal, thyroid, pancreas, ovary, endometrium, cervix, and bladder cancers. Several reports highlighted the clinical significance of ABHD11-AS1 in prognosis, diagnosis, prediction of cancer progression stage, and treatment response. Significantly, the levels of ABHD11-AS1 in gastric juice had been exhibited as a clinical biomarker for the assessment of gastric cancer, while its serum levels have prognostic potential in thyroid cancers. The ABHD11-AS1 has been reported to exert oncogenic effects by sponging different microRNAs (miRNAs), altering signaling pathways such as PI3K/Akt, epigenetic mechanisms, and N6-methyladenosine (m6A) RNA modification. In contrast, the mouse homolog of AHD11-AS1 (Abhd11os) overexpression had exhibited neuroprotective effects against mutant huntingtin-induced toxicity. Considering the emerging research reports, the authors attempted in this first review on ABHD11-AS1 to summarize and highlight its oncogenic potential and clinical significance in different human cancers. Lastly, we underlined the necessity for future mechanistic studies to unravel the role of ABHD11-AS1 in tumor development, prognosis, progression, and targeted therapeutic approaches
Temporal mRNA Expression of Purinergic P2 Receptors in the Brain Following Cerebral Ischemia and Reperfusion: Similarities and Distinct Variations Between Rats and Mice
No full textPurinergic P2 receptors are crucial in energy utilization and cellular signaling, making them key targets for stroke therapies. This study examines the temporal mRNA expression of all P2 receptors in rats and mice. Both species exhibited a common subset of P2X and P2Y receptors with elevated expression following cerebral ischemia and reperfusion (I/R), highlighting conserved mechanisms across these species. The receptors with upregulated expression in both species were P2X3, P2X4, P2X7, P2Y2, and P2Y6. While these similarities were observed, notable differences in receptor expression emerged between rats and mice. Rats exhibited a broader receptor profile, with five additional receptors (P2X1, P2Y1, P2Y12, P2Y13, and P2Y14) significantly upregulated compared to only two receptors (P2X2 and P2Y4) in mice, highlighting species-specific regulation of receptor expression distinct from the shared receptors. Following cerebral I/R, P2Y12 was the most upregulated receptor in rats, while P2Y2 was the most upregulated in mice. These findings reveal both conserved and species-specific changes in P2 receptor expression following cerebral I/R. Targeting purinergic receptors, particularly those conserved and upregulated in response to stroke, may represent a promising therapeutic approach
