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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...
Microsystems technologies are in widespread use. An ever increasing number of automotive functions rely on MEMS/MOEMS applications. Besides the simple quantitative market numbers the correlations in the value chain, the strategic alliances and willingness for cooperation and sharing of information as well as RTD infrastructure are strong indicators for success in a specific application field and geographical...
We assess the performance of a parylene C - aluminum oxide bilayer encapsulation strategy as it applies to implantable devices with non-planar topography. Electrochemical measurements of devices subject to in vitro accelerated lifetime testing are analyzed to evaluate benefits of bilayer encapsulation versus parylene C alone. Failure modes associated with device features and topographies are identified...
3D needle-type glass waveguide arrays were developed as potentially compact neural interfaces for light delivery in deep-tissue. As much as 90% of input light is transmitted via a single optrode to depths >1mm in tissue. Light emission profiles from the optrode tips into tissue can exhibit beam widths of 70–150 μm and full-angle divergence ranging from 13–40°. These beam characteristics may be...
Optical neural control requires light delivery techniques dependent on the experimental goal and biological model. Several light sources and neural interfaces have been implemented featuring one or more of the following criteria: deep illumination, specific and/or comprehensive access, spectral control, temporal precision, high resolution patterning. We've developed 3D needle-type waveguide arrays...
Early-generation waveguide arrays made of silicon (Si) and fused silica (SiO2) were micromachined for infrared (IR) neural stimulation and optogenetics applications in able to provide comprehensive and selective access to distributed targets. Edge-coupled multimode fibers delivered light through the optrodes. Maximum normalized output power from the tips, with respect to the fiber output, was determined...
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...
We evaluate the encapsulation and packaging reliability in fully integrated, fully wireless 100 channel Utah Slant Electrode Array (USEA)/integrated neural interface-recording version 5 (INI-R5) by monitoring the extended long term in-vitro functional stability and recording longevity. The INI encapsulated with 6-µm Parylene-C was immersed in phosphate buffer saline (PBS) for a period of over 12 months...
Several methods for the manufacturing of Iridium Oxide (IrOx) electrodes have been discussed in the literature. Two commonly used fabrication methods are Sputtered Iridium Oxide Films (SIROF) and Activated Iridium Oxide Films (AIROF). Most of the studies for in vivo electrodes have reported optimizations to these methods in the context of stimulation of and recording from neural tissue. In this work...
Ultra high aspect ratio microelectrodes are designed and fabricated to record and stimulate neural signals from deeper areas of the brain and nerves and also to provide a new research tool to the neuroscience community. We present a fabrication process to build ultra high aspect ratio silicon based microelectrode arrays for the neural applications. The mu-wire electrical discharge machining (mu-WEDM)...
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...
In this paper we present a multi-test platform to evaluate the barrier properties of encapsulation materials to be used to encapsulate electronic and implantable medical devices. This test platform leverages multiple material and process evaluation on one single substrate. Both cytotoxicity and cytoproliferation tests are possible, in combination with evaluation of barrier properties and aging monitoring...
The interdisciplinary field of implantable medical microsystems is gaining immense momentum due to the undoubted potential these devices hold in significantly improving the healthcare and also in the basic understanding of several human diseases. The most widely known success stories in this field are those of pacemakers and cochlear implants. However there is a clear need for such devices to mitigate...
A primary goal of the integrated neural interface project (INIP) is to develop a wireless, implantable device capable of recording neural activity from 100 micromachined electrodes. The heart of this recording system is a low-power integrated circuit that amplifies 100 weak neural signals, detects spikes with programmable threshold-crossing circuits, and returns these data via digital radio telemetry...
Recent years have shown the tremendous need for visual recording in consumer, telecom and security. Especially mobile phones have driven that trend to today's ultra-small cameras embedded into the handset. While the image capture IC features ever-decreasing pixel geometries and surging megapixel numbers, the readout circuitry and optical systems are now challenged to follow-up with this trend. This...
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...
We present experimental results from an integrated circuit designed for wireless neural recording applications. The chip, which was fabricated in a 0.6-mum 2P3M BiCMOS process, contains 100 amplifiers and a 10-bit ADC and 902-928 MHz FSK transmitter. Neural signals from one amplifier are sampled by the ADC at 15.7 kSps and telemetered over the FSK wireless data link. Power, clock, and command signals...
Communication systems for implantable medical devices are rapidly advancing. Cardiac, optical, neurological and auditory devices all utilize this technology. Miniaturized antennas and inductive coupling systems provide the radio interface between air and the implantable device. Miniaturized electronics that can be seamlessly integrated with the medical device provide electrical and communication interfaces...
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