6,070 research outputs found
A Micromechanical Parylene Spiral-Tube Sensor and Its Applications of Unpowered Environmental Pressure/Temperature Sensing
A multi-function micromechanical pressure/temperature sensor incorporating a microfabricated parylene
spiral tube is presented. Its visible responses in expression of
in situ rotational tube deformation enable unpowered sensing
directly from optical device observation without electrical or
any powered signal transduction. Sensor characterizations
show promising pressure (14.46°/kPa sensitivity, 0.11 kPa
resolution) and temperature (6.28°/°C sensitivity, 0.24 °C
resolution) responses. Depending on different application
requests, this sensor can be individually utilized to measure
pressure/temperature of systems having one property varying
while the other stabilized, such as intraocular or other in vivo
pressure sensing of certain apparatus inside human bodies or
other biological targets. A straightforward sensor-pair
configuration has also been implemented to retrieve the
decoupled pressure and temperature readouts, hence
ultimately realizes a convenient environmental pressure and
temperature sensing in various systems
Floating-disk parylene micro check valve
A novel micro check valve which has nearly ideal fluidic
shunting behaviors is presented. Featuring a parylene-based
floating disk, this surface-micromachined check valve
ultimately realizes both zero forward cracking pressure and
zero reverse leakage in fluidic operations. Two different
floating disk designs have been implemented to demonstrate
functionality of the microvalve. Experimental data of
underwater testing successfully show that in-channel
floating-disk valves in both designs have great fluidic
performance close to an ideal check valve, except the
additional fluidic resistance in the order of 10^(13) N-s/m^5
based on dimensions of the fabricated devices. Their
pressure loading limit have been confirmed to be higher
than 300 kPa without water leakage. This type of micro
check valve is believed to have great use of flow control in
integrated microfluidics and lab-on-a-chip applications
Design, fabrication and characterization of monolithic embedded parylene microchannels in silicon substrate
This paper presents a novel channel fabrication technology of bulk-micromachined monolithic embedded polymer channels in silicon substrate. The fabrication process favorably obviates the need for sacrifical materials in surface-micromachined channels and wafer-bonding in conventional bulk-micromachined channels. Single-layer-deposited parylene C (poly-para-xylylene C) is selected as a structural material in the microfabricated channels/columns to conduct life science research. High pressure capacity can be obtained in these channels by the assistance of silicon substrate support to meet the needs of high-pressure loading conditions in microfluidic applications. The fabrication technology is completely compatible with further lithographic CMOS/MEMS processes, which enables the fabricated embedded structures to be totally integrated with on-chip micro/nano-sensors/actuators/structures for miniaturized lab-on-a-chip systems. An exemplary process was described to show the feasibility of combining bulk micromachining and surface micromachining techniques in process integration. Embedded channels in versatile cross-section profile designs have been fabricated and characterized to demonstrate their capabilities for various applications. A quasi-hemi-circular-shaped embedded parylene channel has been fabricated and verified to withstand inner pressure loadings higher than 1000 psi without failure for micro-high performance liquid chromatography (µHPLC) analysis. Fabrication of a high-aspect-ratio (internal channel height/internal channel width, greater than 20) quasi-rectangular-shaped embedded parylene channel has also been presented and characterized. Its implementation in a single-mask spiral parylene column longer than 1.1 m in a 3.3 mm × 3.3 mm square size on a chip has been demonstrated for prospective micro-gas chromatography (µGC) and high-density, high-efficiency separations. This proposed monolithic embedded channel technology can be extensively implemented to fabricate microchannels/columns in high-pressure microfludics and high-performance/high-throughput chip-based micro total analysis systems (µTAS)
Parylene stiction
This paper presents a preliminary study into stiction between parylene C and substrate surfaces for biocompatible check-valve applications. During fabrication, parylene C is used as the structural material for the check-valve. The substrate surfaces studied include Au, Al, Si, parylene C, XeF_2 treated Si, and silicon dioxide. Stiction between different surfaces is created after sacrificial photoresist etching. Then, the stiction is measured using blister tests, and stiction mechanisms for different materials are investigated. The devices are released with different recipes to examine their effects. Finally, the results of the study reveal methods to control the cracking pressure of parylene check-valves
FSRNet: End-to-End Learning Face Super-Resolution with Facial Priors
Face Super-Resolution (SR) is a domain-specific super-resolution problem. The
specific facial prior knowledge could be leveraged for better super-resolving
face images. We present a novel deep end-to-end trainable Face Super-Resolution
Network (FSRNet), which makes full use of the geometry prior, i.e., facial
landmark heatmaps and parsing maps, to super-resolve very low-resolution (LR)
face images without well-aligned requirement. Specifically, we first construct
a coarse SR network to recover a coarse high-resolution (HR) image. Then, the
coarse HR image is sent to two branches: a fine SR encoder and a prior
information estimation network, which extracts the image features, and
estimates landmark heatmaps/parsing maps respectively. Both image features and
prior information are sent to a fine SR decoder to recover the HR image. To
further generate realistic faces, we propose the Face Super-Resolution
Generative Adversarial Network (FSRGAN) to incorporate the adversarial loss
into FSRNet. Moreover, we introduce two related tasks, face alignment and
parsing, as the new evaluation metrics for face SR, which address the
inconsistency of classic metrics w.r.t. visual perception. Extensive benchmark
experiments show that FSRNet and FSRGAN significantly outperforms state of the
arts for very LR face SR, both quantitatively and qualitatively. Code will be
made available upon publication.Comment: Chen and Tai contributed equally to this pape
Structural Change in the Stock Market Efficiency after the Millennium: The MACD Approach
This paper studies the profitability of the Moving Average Convergence-Divergence (MACD) trading rule under three different crossing rules: the MACD zero line, the 9-day and 14-day signal lines. It is found that the trading rules perform well in the stock markets of Germany and Hong Kong. Our research also shows that generally the major stock markets around the world have become more efficient after the millennium.
Monolithic High-Aspect-Ratio Embedded Parylene Channel Technology: Fabrication, Integration, and Applications
This paper presents a novel channel fabrication
technology of monolithic bulk-micromachined embedded
channels. Based upon implementing two-step complementary dry
etching technique and conformal parylene C layer deposition,
high-aspect-ratio (internal channel height/internal channel width,
greater than 20) polymer channels with uniform quasirectangular
sidewalls have been successfully fabricated in one silicon wafer. The fabrication is completely compatible with further lithographic CMOS/MEMS process, which enables its total integration with on-chip micro sensors/actuators/structures for lab-on-a-chip applications. An exemplary process has been successfully demonstrated to verify the possibility of combining bulk micromachining and surface micromachining. This proposed formation of channels can be extensively used as beam elements in micromechanical devices or microcolumns for high-performance/high-throughput chip-based separation analysis. A
spiral parylene column longer than 1.1 m embedded in a 3.3 mm
x 3.3 mm chip has been presented as a prospective element in
micro gas-chromatography (µGC)
Floating-disk parylene microvalve for self-regulating biomedical flow controls
A novel self-regulating parylene micro valve is presented in this paper with potential applications for biomedical flow controls. Featuring a free-floating bendable valve disk and two-level valve seat, this surface-micromachined polymeric valve accomplishes miniature pressure/flow rate regulation in a band-pass profile stand-alone without the need of power sources or active actuation. Experimental data of underwater testing results have successfully demonstrated that the microfabricated in-channel valve can regulate water flow at 0-80 mmHg and 0-10 µL/min pressure/flow rate level, which is perfectly suitable for biomedical and lab-on-a-chip applications. For example, such biocompatible microvalve can be incorporated in ocular implants for control of eye fluid drainage to fulfill intraocular pressure (IOP) regulation in glaucoma patients
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