Modeling of Thermoelastic Stress Wave in Laser-Assisted Cell Direct Writing

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Wei Wang ◽  
Yafu Lin ◽  
Yong Huang
Keyword(s):  
Stress Wave ◽  
Cell Injury ◽  
Optical Breakdown ◽  
Thermoelastic Stress ◽  
Laser Pulses ◽  
Stress Wave Propagation ◽  
Direct Write ◽  
Direct Writing ◽  
Coating Materials ◽  
Thermoelastic Stresses

Laser-assisted cell direct-write technique has been a promising biomaterial direct-write method. For safe and reproducible cell direct writing, cell injury due to process-induced external stress must be understood in addition to biological property research. The objective of this study is to model the thermoelastic stress wave propagation inside the coating in laser-assisted cell direct writing when vaporization and/or optical breakdown of coating materials is/are not available. It is found that a bipolar pressure pair, with peak magnitudes on the order of 1 MPa or higher, has been developed within a finite thin coating medium. Shorter duration laser pulses lead to higher thermoelastic stresses. This study will help to understand the photomechanical stress and its relevance with biomaterial damage in laser-assisted cell direct writing.

Modeling of Thermoelastic Stress Wave in Laser-Assisted Cell Direct Writing

2009 ◽  
Author(s):  
Wei Wang ◽  
Yong Huang ◽  
Yafu Lin
Keyword(s):  
Stress Wave ◽  
Cell Damage ◽  
Optical Breakdown ◽  
Thermoelastic Stress ◽  
Laser Pulses ◽  
Stress Wave Propagation ◽  
Direct Write ◽  
Direct Writing ◽  
Coating Materials ◽  
Laser Focal Spot

Laser-assisted cell direct-write technique has been a promising biomaterial direct-write method. For safe and reproducible cell direct writing, the cell damage due to process-induced external stress must be understood in addition to biological property research. The objective of this study is to model the thermoelastic stress wave propagation inside the coating in laser-assisted cell direct writing when the vaporization or optical breakdown of coating materials is not available. It is found that a bipolar pressure pair has been developed within a finite thin coating medium, locations near the laser focal spot experience higher stresses, and shorter duration laser pulses lead to higher thermoelastic stresses. This study will help understand the photomechanical stress and its relevance with biomaterial damage in laser-assisted cell direct writing.

Metallic Foil-Assisted Laser Cell Printing

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Yafu Lin ◽  
Yong Huang ◽  
Douglas B. Chrisey
Keyword(s):  
Cell Viability ◽  
Cell Injury ◽  
Laser Energy ◽  
Layer Structure ◽  
Adhesive Layer ◽  
Laser Evaporation ◽  
Direct Write ◽  
Direct Writing ◽  
Human Colon Cancer ◽  
Metallic Foil

Laser direct-write technology such as modified laser-induced forward transfer (LIFT) is emerging as a revolutionary technology for biological construct fabrication. While many modified LIFT-based cell direct writing successes have been achieved, possible process-induced cell injury and death is still a big hurdle for modified LIFT-based cell direct writing to be a viable technology. The objective of this study is to propose metallic foil-assisted LIFT using a four-layer structure to achieve better droplet size control and increase cell viability in direct writing of human colon cancer cells (HT-29). The proposed four layers include a quartz disk, a sacrificial and adhesive layer, a metallic foil, and a cell suspension layer. The bubble formation-induced stress wave is responsible for droplet formation. It is found that the proposed metallic foil-assisted LIFT approach is an effective cell direct-write technology and provides better printing resolution and high post-transfer cell viability when compared with other conventional modified LIFT technologies such as matrix-assisted pulsed-laser evaporation direct-write; at the same time, the possible contamination from the laser energy absorbing material is minimized using a metallic foil.

scholarly journals Optical Sensitivity of Waveguides Inscribed in Nanoporous Silicate Framework

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 123
Author(s):  
Zhong Lijing ◽  
Roman A. Zakoldaev ◽  
Maksim M. Sergeev ◽  
Andrey B. Petrov ◽  
Vadim P. Veiko ◽  
...  
Keyword(s):  
Refractive Index ◽  
Near Field ◽  
Experimental Studies ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Direct Writing ◽  
Sensor Applications ◽  
Refractive Index Contrast ◽  
Optical Sensitivity ◽  
Index Contrast

Laser direct writing technique in glass is a powerful tool for various waveguides’ fabrication that highly develop the element base for designing photonic devices. We apply this technique to fabricate waveguides in porous glass (PG). Nanoporous optical materials for the inscription can elevate the sensing ability of such waveguides to higher standards. The waveguides were fabricated by a single-scan approach with femtosecond laser pulses in the densification mode, which resulted in the formation of a core and cladding. Experimental studies revealed three types of waveguides and quantified the refractive index contrast (up to Δn = 1.2·10−2) accompanied with ~1.2 dB/cm insertion losses. The waveguides demonstrated the sensitivity to small objects captured by the nanoporous framework. We noticed that the deposited ethanol molecules (3 µL) on the PG surface influence the waveguide optical properties indicating the penetration of the molecule to its cladding. Continuous monitoring of the output near field intensity distribution allowed us to determine the response time (6 s) of the waveguide buried at 400 µm below the glass surface. We found that the minimum distinguishable change of the refractive index contrast is 2 × 10−4. The results obtained pave the way to consider the waveguides inscribed into PG as primary transducers for sensor applications.

FEM Stress Analysis and Strength of Scarf Adhesive Joints of Similar Adherend Subjected to Impact Tensile Loadings

2007 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Yuya Hirayama ◽  
He Dan
Keyword(s):  
Young’S Modulus ◽  
Principal Stress ◽  
Stress Wave ◽  
Young's Modulus ◽  
Three Dimensional ◽  
Maximum Principal Stress ◽  
Adhesive Joints ◽  
Stress Wave Propagation ◽  
Adhesive Thickness ◽  
Three Dimensional Finite Element

The stress wave propagation and stress distribution in scarf adhesive joints have been analyzed using three-dimensional finite element method (FEM). The FEM code employed was LS-DYNA. An impact tensile loading was applied to the joint by dropping a weight. The effect of the scarf angle, Young’s modulus of the adhesive and adhesive thickness on the stress wave propagations and stress distributions at the interfaces have been examined. As the results, it was found that the point where the maximum principal stress becomes maximum changes between 52 degree and 60 degree under impact tensile loadings. The maximum value of the maximum principal stress increases as scarf angle decreases, Young’s modulus of the adhesive increases and adhesive thickness increases. In addition, Experiments to measure the strains and joint strengths were compared with the calculated results. The calculated results were in fairly good agreements with the experimental results.

Effect of interlayer on stress wave propagation in CMC/RHA multi-layered structure

2010 ◽  
Vol 70 (12) ◽  
pp. 1669-1673 ◽  
Author(s):  
Yangwei Wang ◽  
Fuchi Wang ◽  
Xiaodong Yu ◽  
Zhuang Ma ◽  
Jubin Gao ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Stress Wave ◽  
Layered Structure ◽  
Stress Wave Propagation
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