Traumatic Brain Injury (TBI) occurs when an external force injures the brain. While clinical outcomes of TBI can vary widely in severity, few mechanisms of neurodegeneration following TBI have been identified for treatment. Understanding mechanotransduction in cells is key to understanding cellular response to injury. This has been previously studied using a variety of optical techniques such as laser tweezers, laser ablation, and others. We propose a model utilizing photodisruption for studying the early pathogenesis of TBI in primary neuron cultures by generating laser-induced shockwaves (LISs). Photodisruption allows for the generation of spatiotemporally defined shear stress against cells. The shear stress exerted by the shockwave is between 0 - 50 kPa depending on the distance from the shockwave epicenter. Cells typically situated at a distance from the epicenter of 50 m undergo necrosis while viability is preserved for those located at a distance of 100 m. An optical system was developed that allows single cells to be selectively studied in response to LISs. Approximate timescales of each of the effects culminating in shockwave generation span several orders of magnitude from nanoseconds to milliseconds. Thus, our system utilizes Pockels cells — a high-speed, electro-optical shutter — to capture shockwave dynamics. The force measurement system is characterized by imaging stages over the period of cavitation then, violent expansion and collapse of microbubbles responsible for shockwave generation. Here, we visualize LISs and observe subsequent, morphological responses elicited by cells under a range of forces generated from optical breakdown.
Traumatic Brain Injury (TBI) occurs when an external force injures the brain. While clinical outcomes of TBI can vary widely in severity, few mechanisms of neurodegeneration following TBI have been identified for treatment. We propose a model for studying TBI using laser-induced shockwaves (LISs). An optical system was developed that allows single cells to be studied in response to LISs. Our system utilizes an optically-coupled force measurement component that allows for the visualization of shockwave dynamics. Here, the force measurement system is characterized by imaging stages over the period of violent expansion and collapse of microbubbles responsible for shockwave generation.
We present SiCloud (Silicon Photonics Cloud), the first free, instructional web-based research and education tool for
silicon photonics. SiCloud’s vision is to provide a host of instructional and research web-based tools. Such interactive
learning tools enhance traditional teaching methods by extending access to a very large audience, resulting in very high
impact. Interactive tools engage the brain in a way different from merely reading, and so enhance and reinforce the
learning experience. Understanding silicon photonics is challenging as the topic involves a wide range of disciplines,
including material science, semiconductor physics, electronics and waveguide optics. This web-based calculator is an
interactive analysis tool for optical properties of silicon and related material (SiO2, Si3N4, Al2O3, etc.). It is designed to
be a one stop resource for students, researchers and design engineers. The first and most basic aspect of Silicon
Photonics is the Material Parameters, which provides the foundation for the Device, Sub-System and System levels.
SiCloud includes the common dielectrics and semiconductors for waveguide core, cladding, and photodetection, as well
as metals for electrical contacts. SiCloud is a work in progress and its capability is being expanded. SiCloud is being
developed at UCLA with funding from the National Science Foundation’s Center for Integrated Access Networks
(CIAN) Engineering Research Center.