David S. Pellinen

Flexible polyimide-based intracortical electrode arrays with bioactive capability

The promise of advanced neuroprosthetic systems to significantly improve the quality of life for a segment of the deaf, blind, or paralyzed population hinges on the development of an efficacious, and safe, multichannel neural interface for the central nervous system. The candidate implantable device that is to provide such an interface must exceed a host of exacting design parameters. The authors present a thin-film, polyimide-based, multichannel intracortical Bio-MEMS interface manufactured with standard planar photo-lithographic CMOS-compatible techniques on 4-in silicon wafers. The use of polyimide provides a mechanically flexible substrate which can be manipulated into unique three-dimensional designs. Polyimide also provides an ideal surface for the selective attachment of various important bioactive species onto the device in order to encourage favorable long-term reactions at the tissue-electrode interface. Structures have an integrated polyimide cable providing efficient contact points for a high-density connector. This report details in vivo and in vitro device characterization of the biological, electrical and mechanical properties of these arrays. Results suggest that these arrays could be a candidate device for long-term neural implants.

3-D silicon probe array with hybrid polymer interconnect for chronic cortical recording

The desire to perform chronic recordings from many channels in cortex is high among both neuroscientists and neural prosthesis researchers. The Michigan probe with integrated silicon ribbon cable has been used successfully for obtaining chronic cortical recordings in rodents. As these silicon devices are applied in larger animals and potentially in humans, however, a more mechanically robust, scalable system is required. Here we present a device that takes advantage of several existing, well-characterized technologies and methods and combines them to form a hybrid cortical assembly. The components of the assembly include thin-film multichannel silicon probes and polyimide cables that are electrically and mechanically coupled using thermocompression ball bonding. The resulting probe/cable assembly is low profile (<500 microns) and can be combined with other assemblies to form a 3-D array. Sixteen channel 2-D arrays have been implanted into rat motor cortex and have recorded chronic unit activity.

A Novel Lead Design for Modulation and Sensing of Deep Brain Structures

Goal: Develop and characterize the functionality of a novel thin-film probe technology with a higher density of electrode contacts than are currently available with commercial deep brain stimulation (DBS) lead technology. Such technology has potential to enhance the spatial precision of DBS and enable a more robust approach to sensing local field potential activity in the context of adaptive DBS strategies. Methods: Thin-film planar arrays were microfabricated and then assembled on a cylindrical carrier to achieve a lead with 3-D conformation. Using an integrated and removable stylet, the arrays were chronically implanted in the subthalamic nucleus and globus pallidus in two parkinsonian nonhuman primates. Results: This study provides the first in vivo data from chronically implanted DBS arrays for translational nonhuman primate studies. Stimulation through the arrays induced a decrease in parkinsonian rigidity, and directing current around the lead showed an orientation dependence for eliciting motor capsule side effects. The array recordings also showed that oscillatory activity in the basal ganglia is heterogeneous at a smaller scale than detected by the current DBS lead technology. Conclusion: These 3-D DBS arrays provide an enabling tool for future studies that seek to monitor and modulate deep brain activity through chronically implanted leads. Significance: DBS lead technology with a higher density of electrode contacts has potential to enable sculpting DBS current flow and sensing biomarkers of disease and therapy.

Silicon-substrate intracortical microelectrode arrays with integrated electronics for chronic cortical recording

Advances in BioMBMS have provided researchers with the capabilities to look at a myriad of things with more detail and precision than ever before, and the brain is no exception to this. The brain is becoming more accessible and controllable on almost every level; the challenge lies in increasing the quality of the interface with the brain. To address this challenge, we must begin by optimizing to the best of our capabilities the implantable devices used. One method to help optimize these devices is to integrate active electronics on the microelectrode that will enhance the quality of the signals being extracted from brain. This paper describes a chronic silicon-substrate microelectrode with integrated analog-front end electronics capable of recording from nearby neurons in active and passive modes of operation. Six-channel 2-D arrays have been chronically implanted into barrel cortex of two rats and have recorded chronic unit activity with SNRs up to 8:1.