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Passively Q-switched microchip lasers are very attractive for various applications because of their sub-nanosecond pulse width, simple and rugged construction and low-cost [1]. We have earlier reported the design of Nd:YAG/Cr4+:YAG passively Q-switched microchip lasers for efficient wavelength conversion from the second to the ninth harmonic [2]. These lasers are useful for spectroscopy, LIDAR, LIBS,...
Neural microelectrodes can record from and stimulate neurons in the central and peripheral nervous systems. They play a critical role for the development of neural prostheses to restore lost motor or sensory functions of the body. Existing commercial devices (such as the Utah array) exhibit a lifetime of few months to several years. For clinical applications, it is desirable for these microelectrodes...
With the advent of silicon micromachining, biomaterials and advanced technology, it is becoming possible to fabricate more sophisticated implantable neural arrays that can record from and stimulate neurons and nerve axons in the central and peripheral nervous system. To access large portion of human brain, neural arrays with hundreds of channels are needed. The Utah Electrode Array (UEA) is one example...
Neural interfaces connect signal processing electronics to the nervous system via implanted microelectrode arrays such as the Utah electrode array (UEA). The UEA is coated with a biocompatible Parylene-C layer. However, in order to form active sites, Parylene-C is removed from the electrode tips of the UEA. Currently, this is achieved by manually punching aluminum foil through the electrodes to the...
In the last two decades, though the field of neuroprosthetics has gained tremendous momentum through the development of novel neural interfaces, however, till date there is no ideal device available. One of the critical requirements of the neural interface is to have higher electrode density to map neurons from large volume of brain but not at the expense of increasing the device footprint. There...
We report the use of [100]-cut YAG/Nd:YAG composite in a microchip laser to reduce depolarization at high average power. Consequently, we achieve FHG giving > 0.5 MW peak power, 1 kHz at 266 nm.
Passively Q-switched microchip lasers have proved to be ideal laser sources for efficient wavelength conversion. These lasers have several advantages, such as, simple construction, compact size and ease-of-use. They also provide very high peak powers that enable efficient wavelength conversion. Recently, we have used the sub-nanosecond ‘pulse-gap’ region of Nd:YAG/Cr4+:YAG passively Q-switched microchip...
Advances in neuroprostheses are strongly dependent on the development of microelectrodes with an enhanced ability to selectively record or stimulate neural signals. Selectivity for a microelectrode depends on its ability to interact with a small number of neurons and/or nerve fibers. In order to achieve selective electrical transduction, the surface area of active site should be on the order of tens...
In MEMS technology there is an increasing interest in developing high aspect ratio silicon columns having rounded corners, slightly positive tapered shaft, sharp tips, and smooth surface. A precise control of the profile can be used for different applications, such as for molds used in polymer hot embossing processes, micro needles used for drug delivery and blood sampling, and neural probes used...
Compact, passively Q-switched, microchip lasers are attractive for many applications, such as, microprocessing, remote sensing, laser ignition, etc., due to their short pulse-width and high peak power characteristics [1–5]. The high peak power of microchip lasers can also be used for efficient harmonic conversion to the green and UV wavelengths for a variety of applications. However, Nd:YAG microchip...
Advances in silicon micromachining have lead to development of sophisticated neural interfaces such as the Utah slant electrode array (USEA). The unique architecture of the USEA comprises of electrodes which increase in length in one direction, while being constant in length in the other. When implanted into a peripheral nerve, the tips of the electrodes penetrate nerve fascicles, and are close to...
As photovoltaic systems proliferate on grids, larger numbers of inverters will be interconnected with each other through their host utility. This becomes especially true if string inverters (SIs) or AC module ldquomicroinvertersrdquo are used. It will thus become increasingly important to ensure that the islanding detection methods used are effective in this so-called ldquomulti-inverter caserdquo...
The classical linear instability method (CLIM) of islanding prevention works by manipulating the control loop of a photovoltaic inverter such that when the utility disappears, right-half-plane poles appear, and the inverter becomes unstable, eventually leading to a shutdown due to abnormal voltage or frequency. The CLIM has been less well-studied than other methods, so in this work, a MATLAB/Simulink...
This paper presents a novel design and development of a self-aligning latch-up mechanism for out of plane, high density, three dimensional penetrating micro electrode array used for neural prosthesis. The microsystem consists of two components; male and female. The male component has 100 neural electrodes with one row of edge column having a "mushroom" geometry, and corner posts at the four...
The lack of safe, reliable, automated and clinically acceptable blood sampling has been the main problem impeding the development of real-time systems for blood analysis and subsequent closed-loop physiological function control. A key component of a real-time implantable blood sampling microsystem is a microneedle array which directly interfaces with the electronics and tissue. The primary motivation...
A novel fabrication technique has been developed for creating high density (7.7 electrodes/mm2 ), out of plane, high aspect ratio silicon-based convoluted microelectrode arrays for neural and retinal prosthesis. The unique convoluted shape of the electrodes compliments the curved surface of nerves, and in the case of retina, its spherical geometry. This electrode array's geometry has the potential...
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