scholarly journals Capillary Microvalve Actuation Using Thermal Expansion of Trapped Air Bubble

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 1031
Author(s):  
Ujjal Barman ◽  
Paolo Fiorini ◽  
Liesbet Lagae ◽  
Benjamin Jones
Keyword(s):  
Thermal Expansion ◽  
Silicon Substrate ◽  
Voltage Pulse ◽  
Capillary Barrier ◽  
Air Bubble ◽  
Trapped Air ◽  
Actuation Mechanism ◽  
Air Chamber

In this study, we demonstrate a compact actuation mechanism of a silicon capillary stop microvalve, based on electrothermal expansion of a trapped air bubble in a chamber. The bubble is heated using an integrated aluminum microheater deposited on the silicon substrate above the air chamber. The heater occupies an area of 320 µm × 300 µm and has a resistance of 40 Ohms. By applying a 500 ms voltage pulse of 3 V amplitude we could generate a pressure sufficient to breach the capillary barrier pressure of valve, which is around 1000 Pa.

On Testing to Predict the Need for Eructation

PEDIATRICS ◽  
1971 ◽  
Vol 47 (2) ◽  
pp. 475-476
Author(s):  
Claude M. Penchina
Keyword(s):  
Air Bubble ◽  
Trapped Air ◽  
Popular Book

Curiously enough, neither eructation, nor burping, nor belching, nor bubbling can be found in the indexes of the popular textbooks by Nelson1 and Holt,2 though air-swallowing in relation to colic, regurgitation, and vomiting is, of course, described. Furthermore, neither of these texts nor the popular book by Spock,3 describes any operational means (other than observation of pain and discomfort) to determine the existence of a trapped air bubble. We have found a simple audio test to determine the presence of a large trapped air bubble in an infant's stomach before it becomes painful.

Dynamic interface tension of a smectic liquid crystal in anionic surfactant solutions

2015 ◽  
Vol 17 (39) ◽  
pp. 26198-26206 ◽  
Author(s):  
Kirsten Harth ◽  
Larissa M. Shepherd ◽  
James Honaker ◽  
Ralf Stannarius
Keyword(s):  
Liquid Crystal ◽  
Critical Micelle Concentration ◽  
Anionic Surfactant ◽  
Ionic Surfactant ◽  
Interface Tension ◽  
Air Bubble ◽  
Trapped Air ◽  
Smectic Liquid Crystal ◽  
Surfactant Solutions ◽  
Dynamic Interface

The interface tension of a smectic liquid crystal to ionic surfactant solutions is investigated at concentrations above and below the critical micelle concentration using the buoyancy of a trapped air bubble.

The Research about the III-Nitride Compounds Epitaxially Grown on Si Substrate

2011 ◽  
Vol 399-401 ◽  
pp. 935-944
Author(s):  
Ai Ping Zhao ◽  
Hong Deng ◽  
Feng Liu ◽  
Xue Ran Deng
Keyword(s):  
Thermal Expansion ◽  
Silicon Substrate ◽  
Lattice Mismatch ◽  
Development Trend ◽  
Si Substrate ◽  
Selective Area ◽  
Large Lattice ◽  
Large Lattice Mismatch ◽  
The Development Trend ◽  
Growth Technology

The III-nitride compounds epitaxially grown on Si substrate have attracted more and more attentions and some progress have been achieved. Many methods have been tried to tackle the issue which caused by the large lattice mismatch and thermal expansion coefficient mismatches between silicon substrate and the III-nitride compounds. This paper presents buffer layer technology, selective area and lateral epitaxial over growth technology, and presents the researches about the III-nitride devices. Semi polar and non-polar GaN films grown on Si (such as Si(110), Si(112), Si(001) et al.) also have been instructed. At the end of this paper, the development trend of epitaxial technology has been discussed.

Bubble-Induced Relaxation in High-Pressure Microfluidic Systems

2013 ◽  
Vol 562-565 ◽  
pp. 581-584
Author(s):  
Bao Jun Wang ◽  
Fei Xie ◽  
Wei Wang ◽  
Wen Gang Wu ◽  
Zhi Hong Li
Keyword(s):  
High Pressure ◽  
Flow Resistance ◽  
Relaxation Times ◽  
Air Bubbles ◽  
Microfluidic Systems ◽  
Design Guideline ◽  
Pressure Relaxation ◽  
Air Bubble ◽  
Trapped Air

This work reported an analysis of a noticeable relaxation phenomenon caused by undesirable air bubbles in high-pressure microfluidic systems. A model with compression of air bubble considered was established to address the experimental observed pressure relaxation. The results indicated that the dominative factors were flow rate, flow resistance and initial diameter of the trapped air bubble. Meanwhile, the calculated relaxation times in different cases provided a design guideline for high-pressure microfluidic chip to avoid the long-term pressure relaxation.

Bubble Nucleation and Growth on Surface of Rapidly Heated Micro Heaters

2002 ◽  
Author(s):  
Jung-Yeul Jung ◽  
Hong-Chul Park ◽  
Ho-Young Kwak
Keyword(s):  
Silicon Substrate ◽  
Voltage Pulse ◽  
Bubble Growth ◽  
Nucleation And Growth ◽  
Bubble Nucleation ◽  
The Other ◽  
Time Dependent ◽  
Working Fluid ◽  
Superheat Limit ◽  
Collapse Process

Time dependent surface temperatures on a micro heater were measured when a voltage pulse of 25~200 μs was applied to the heater. The dimensions of the micro polysilicon heaters fabricated on a silicon substrate are 50×5×0.523 μm3 for a micro line heater and 65×65×0.523 μm3 for a micro square heater. With the minimum voltage needed for bubble growth, the temperature for bubble nucleation on the heater immersed in FC-72 was measured to be 420.7 K for the micro line heater, which is close to the superheat limit of the working fluid. On the other hand a bubble nucleates at temperature of 388 K on the square heater. Bubble nucleation, growth and subsequent collapse process were visualized by a microscope-35 mm camera with a μs flash unit.

Effect of the Cross-Sectional Shape of Recirculation Channel on Expelling Air Bubbles in the FDBs of HDD Spindle Motors

2014 ◽  
Author(s):  
Y. H. Jung ◽  
G. H. Jang ◽  
C. H. Kang ◽  
H. H. Shin ◽  
J. Y. Jeong
Keyword(s):  
Fluid Dynamic ◽  
Hard Disk Drives ◽  
Navier Stokes ◽  
Air Bubbles ◽  
Navier Stokes Equation ◽  
Cross Sectional ◽  
Air Bubble ◽  
Trapped Air ◽  
Large Pressure ◽  
Fast Flow

Fluid dynamic bearings (FDBs) are applied to most of the spindle motors of computer hard disk drives (HDDs) since FDBs provide better dynamic characteristics, such as lower vibration and noise, than ball bearings. However, a weakness of FBDs is instability arising from air bubbles in the oil lubricant of FDBs. One possible solution to expel the trapped air bubbles out of FDBs is to include recirculation channel (RC). RC is designed to balance the pressures between upper and lower parts of FDBs and to circulate the oil lubricant as well as to expel air bubbles out of FDBs. This paper experimentally and numerically investigates the behavior of the air bubble in oil lubricant of operating FDBs due to the design of the RC. We created the FDBs with transparent cover and performed the experiment to visually observe the behavior of trapped air bubbles. Also, we numerically studied the phenomena of expelling the air bubble. The flow field of FDBs is calculated by the Navier-Stokes equation and the continuity equation. And we numerically explained that large pressure difference between upper and lower regions of RC and fast flow velocity along RC expel the air bubble out of FDBs. This research can be effectively utilized to develop robust FDBs by expelling the air bubbles out of FDBs.

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