Negi S.,Blackrock Microsystems |
Bhandari R.,Blackrock Microsystems |
Solzbacher F.,University of Utah
2011 16th International Solid-State Sensors, Actuators and Microsystems Conference, TRANSDUCERS'11 | Year: 2011
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 for controlling motor or sensory prosthetic devices. The mixture of hydrofluoric acid (HF) and nitric acid (HNO3) is an isotropic etchant and is used in MEMS technology to etch silicon. We present a novel way of isotropically and anisotropically etch MEMS structures using the HF-HNO 3 etchant. The shape and size of the structure is controlled by the dynamics of reactants. © 2011 IEEE. Source
Xie X.,University of Utah |
Rieth L.,University of Utah |
Negi S.,University of Utah |
Bhandari R.,Blackrock Microsystems |
And 4 more authors.
Journal of Micromechanics and Microengineering | Year: 2014
The recently developed alumina and parylene C bilayer encapsulation improved the lifetime of neural interfaces. Tip deinsulation of Utah electrode array based neural interfaces is challenging due to the complex 3D geometries and high aspect ratios of the devices. A three-step self-aligned process was developed for tip deinsulation of bilayer encapsulated arrays. The deinsulation process utilizes laser ablation to remove parylene C, O2 reactive ion etching to remove carbon and parylene residues, and buffered oxide etch to remove alumina deposited by atomic layer deposition, and expose the IrO x tip metallization. The deinsulated iridium oxide area was characterized by scanning electron microscopy, atomic force microscopy, x-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy to determine the morphology, surface morphology, composition, and electrical properties of the deposited layers and deinsulated tips. The alumina layer was found to prevent the formation of micro cracks on iridium oxide during the laser ablation process, which has been previously reported as a challenge for laser deinsulation of parylene films. The charge injection capacity, charge storage capacity, and impedance of deinsulated iridium oxide were characterized to determine the deinsulation efficacy compared to parylene-only insulation. Deinsulated iridium oxide with bilayer encapsulation had higher charge injection capacity (240 versus 320 nC) and similar electrochemical impedance (2.5 versus 2.5 k) compared to deinsulated iridium oxide with only parylene coating for an area of 2 × 10-4 cm2. Tip impedances were in the range of 20-50 k, with a median of 32 k and a standard deviation of 30 k, showing the effectiveness of the self-aligned deinsulation process for alumina and parylene C bilayer encapsulation. The relatively uniform tip impedance values demonstrated the consistency of tip exposures. © 2014 IOP Publishing Ltd. Source
Kiss T.,Pfizer |
Hoffmann W.E.,Pfizer |
Scott L.,Pfizer |
Kawabe T.T.,Pfizer |
And 3 more authors.
Frontiers in Psychiatry | Year: 2011
NMDA receptor (NMDAR) antagonists, such as phencyclidine, ketamine, or dizocilpine (MK-801) are commonly used in psychiatric drug discovery in order to model several symptoms of schizophrenia, including psychosis and impairments in working memory. In spite of the widespread use of NMDAR antagonists in preclinical and clinical studies, our understanding of the mode of action of these drugs on brain circuits and neuronal networks is still limited. In the present study spontaneous local field potential (LFP), multi- (MUA) and single-unit activity, and evoked potential, including paired-pulse facilitation (PPF) in response to electrical stimulation of the ipsilateral subiculum were carried out in the medial prefrontal cortex (mPFC) in urethane anesthetized rats. Systemic administration of MK-801 (0.05 mg/kg, i.v.) decreased overall MUA, with a diverse effect on single-unit activity, including increased, decreased, or unchanged firing, and in line with our previous findings shifted delta-frequency power of the LFP and disrupted PPF (Kiss et al., 2011). In order to provide further insight to the mechanisms of action of NMDAR antagonists, MK-801 was administered intracranially into the mPFC and mediodorsal nucleus of the thalamus (MD). Microinjections of MK-801, but not physiological saline, localized into the MD evoked changes in both LFP parameters and PPF similar to the effects of systemically administered MK-801. Local microinjection of MK-801 into the mPFC was without effect on these parameters. Our findings indicate that the primary site of the action of systemic administration of NMDAR antagonists is unlikely to be the cortex. We presume that multiple neuronal networks, involving thalamic nuclei contribute to disrupted behavior and cognition following NMDAR blockade. © 2011 Kiss, Hoffmann, Scott, Kawabe, Milici, Nilsen and Hajós. Source
Wang J.,Brown University |
Wagner F.,Brown University |
Borton D.A.,Brown University |
Zhang J.,Yale University |
And 6 more authors.
Journal of Neural Engineering | Year: 2012
Studying brain function and its local circuit dynamics requires neural interfaces that can record and stimulate the brain with high spatiotemporal resolution. Optogenetics, a technique that genetically targets specific neurons to express light-sensitive channel proteins, provides the capability to control central nervous system neuronal activity in mammals with millisecond time precision. This technique enables precise optical stimulation of neurons and simultaneous monitoring of neural response by electrophysiological means, both in the vicinity of and distant to the stimulation site. We previously demonstrated, in vitro, the dual capability (optical delivery and electrical recording) while testing a novel hybrid device (optrode-MEA), which incorporates a tapered coaxial optical electrode (optrode) and a 100 element microelectrode array (MEA). Here we report a fully chronic implant of a new version of this device in ChR2-expressing rats, and demonstrate its use in freely moving animals over periods up to 8 months. In its present configuration, we show the device delivering optical excitation to a single cortical site while mapping the neural response from the surrounding 30 channels of the 6 × 6 element MEA, thereby enabling recording of optically modulated single-unit and local field potential activity across several millimeters of the neocortical landscape. © 2012 IOP Publishing Ltd. Source
Blackrock Microsystems | Date: 2012-11-05
Measuring and recording system primarily for medical diagnostic purposes comprised of apparatus and instruments, namely, computer hardware, software, microelectrode arrays, electrodes, acute and chronic connectors, fiber optic links, metal microelectrodes, silicon probes, grids, and array inserters for the purpose of monitoring, recording, analyzing, and storing of human brain and peripheral nerve electrical activity. Product research and development; consultation services in the field of neuroscience research, neural engineering; product research and development consultation in the field of neuroprosthetics.