Search PubMed⌕ Search

Biomedical subjects

Jack W Judy

Publications and source records attributed to Jack W Judy.

4 recordsLinked to original sources
PubMed2006

A TinyOS-enabled MICA2-based wireless neural interface.

Existing approaches used to develop compact low-power multichannel wireless neural recording systems range from creating custom-integrated circuits to assembling commercial-off-the-shelf (COTS) PC-based components. Custom-integrated-circuit designs yield extremely compact and low-power devices at the expense of high development and upgrade costs and turn-around times, while assembling COTS-PC-technology yields high performance at the expense of large system size and increased power consumption. To achieve a balance between implementing an ultra-compact custom-fabricated neural transceiver and assembling COTS-PC-technology, an overlay of a neural interface upon the TinyOS-based MICA2 platform is described. The system amplifies, digitally encodes, and transmits neural signals real-time at a rate of 9.6 kbps, while consuming less than 66 mW of power. The neural signals are received and forwarded to a client PC over a serial connection. This data rate can be divided for recording on up to 6 channels, with a resolution of 8 bits/sample. This work demonstrates the strengths and limitations of the TinyOS-based sensor technology as a foundation for chronic remote biological monitoring applications and, thus, provides an opportunity to create a system that can leverage from the frequent networking and communications advancements being made by the global TinyOS-development community.

Amplifiers, Electronic↗
PubMed2005

Multielectrode microprobes for deep-brain stimulation fabricated with a customizable 3-D electroplating process.

Although deep-brain stimulation (DBS) can be used to improve some of the severe symptoms of Parkinson's disease (e.g., Bradykinesia, rigidity, and tremors), the mechanisms by which the symptoms are eliminated are not well understood. Moreover, DBS does not prevent neurodegeneration that leads to dementia or death. In order to fully investigate DBS and to optimize its use, a comprehensive long-term stimulation study in an animal model is needed. However, since the brain region that must be stimulated, known as the subthalamic nucleus (STN), is extremely small (500 microm x 500 microm x 1 mm) and deep within the rat brain (10 mm), the stimulating probe must have geometric and mechanical properties that allow accurate positioning in the brain, while minimizing tissue damage. We have designed, fabricated, and tested a novel micromachined probe that is able to accurately stimulate the STN. The probe is designed to minimize damage to the surrounding tissue. The probe shank is coated with gold and the electrode interconnects are insulated with silicon nitride for biocompatibility. The probe has four platinum electrodes to provide a variety of spatially distributed stimuli, and is formed in a novel 3-D plating process that results in a microwire like geometry (i.e., smoothly tapering diameter) with a corresponding mechanically stable shank.

Animals↗
PubMed2004

An ultra small array of electrodes for stimulating multiple inputs into a single neuron.

We have developed an ultra small, translucent array of electrodes for use in the parasaggital cerebellar slice preparation. This positionable array is capable of stimulating multiple independent bundles of parallel fibers (PFs), which synapse onto a single Purkinje neuron. On a silicon substrate, a low-stress silicon nitride film was used both as a structural layer and as electrical insulation. Evaporated gold pads and interconnects were sandwiched between two such layers. A bulk anisotropic silicon etch released the individual arrays. The electrodes are supported within a 2-microm-thick cantilever of translucent silicon nitride. In one design, eight 4-microm-wide square electrodes are arranged on 8-microm-centers. Another design, half the scale of the first, was also tested. The array was mounted on a micromanipulator and can be visualized by an upright microscope. It can then be positioned in the dendritic arbor of a Purkinje neuron while not disturbing a recording pipette at the soma. Paired-pulse facilitation experiments have confirmed that the electrodes are capable of stimulating non-overlapping bundles of PFs. This device will be useful for exploring spatiotemporal synaptic integration in single neurons. Potential applications in experiments on cerebellar LTD are also discussed.

Animals↗