We have investigated the effect of the dynamics of crater size on the poly(dimethylsiloxane) (PDMS) surface morphology in fs-laser micro-processing. PDMS surface was processed with varying both inter-pulse interval and inter-spot distance between successive laser pulses. With keeping the interval of 5 ms crater shape is round even if the spot is overlapped in space. But decreasing the interval to 0.02 ms the shape of the crater is no longer round. Decreasing the inter-distance between the craters results in roughened surface morphology even at time intervals of 5 ms. Temporal dependence of single-shot fs-laser induced crater size was measured as a function of time delay. Within 0.1 ms after pulse irradiation with a fluence of 4.8 J/cm2 on PDMS surface the crater size has reached to its maximum values and then decreased with a time constant of about 0.3 ms. The surface morphology after fs-laser pulse irradiation is strongly dependent on not only inter-spot distance between successive laser pulse but also their inter-pulse intervals. By proposing a theoretical model on their dynamic features, we will try to explain the current observation in quantitatively.

In this work, we refer to the fraction of hydrides and vinyl groups consumed in cross‐linking reaction as a variation of the properties of poly(dimethylsiloxane) (PDMS) with varying the formulation of a curing agent from 3.2 wt % to 50 wt %. Young's modulus, density, and refractive indices of PDMS were observed to have a maxima at a formulation of about 10 wt % of cross linker. The intensity of the Raman band for the SiH stretching mode in cross‐linker is almost zero if the cross‐linking agent is less than 10 wt %, but it is linearly increasing with increasing the content of cross‐linker. The dependence of the elastic modulus on the formulation could be explained in terms of the fraction of cross‐linked network. The analytical framework proposed in this work could be used for optimizing the formulation of PDMS and hence its properties can be tailored for specific applications.

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Abstract:In this work, we demonstrate that ultrafast laser irradiation could selectively disrupt vascular endothelium of zebrafish embryos in vivo. Ultrafast lasers minimize the collateral damage in the vicinity of the laser focus and eventually reduce coagulation in the tissues. We have also found that the threshold fluence for lesion formation of the vascular endothelium strongly depends on the developmental stage of the embryos. The threshold laser fluence required to induce apparent lesions in the vascular structure for Somite 14, 20 and 25 stages is about 5 J/cm 2 ~7 J/cm 2 , which is much lower than that for the later development stages of Prim 16 and Prim 20 of 30 J/cm 2 ~50 J/cm 2 . The proposed method for treating the vascular cord of zebrafish embryos in the early stage of development has potential as a selective and effective method to induce a fatal lesion in the vascular endothelium without damaging the developed blood vessels. Optimal parameters for exogenous material delivery, and the laser's effect on short-and long-term development," BMC Biotechnol. 8(1), 7 (2008). 18. M.

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