Harnessing the Inflammatory Reflex for the Treatment of Inflammation-Mediated Diseases

Treating diseases nonpharmacologically, using targeted neurostimulation instead of systemic drugs, is a hallmark of the burgeoning field of bioelectronic medicine. In this review, we provide a brief overview of the discovery and function of the prototypical neuroimmune reflex, the "inflammatory reflex." We discuss various biomarkers developed and used to translate early physiological discoveries into dosing parameters used in experimental settings, from the treatment of animal models of disease through a proof-of-concept clinical study in rheumatoid arthritis (RA). Finally, we relate how unique aspects of this form of therapy enabled the design of a next-generation implanted pulse generator using integrated electrodes, currently under evaluation in a U.S.-based clinical study for patients with drug refractory RA.

A Review: Electrode and Packaging Materials for Neurophysiology Recording Implants

To date, a wide variety of neural tissue implants have been developed for neurophysiology recording from living tissues. An ideal neural implant should minimize the damage to the tissue and perform reliably and accurately for long periods of time. Therefore, the materials utilized to fabricate the neural recording implants become a critical factor. The materials of these devices could be classified into two broad categories: electrode materials as well as packaging and substrate materials. In this review, inorganic (metals and semiconductors), organic (conducting polymers), and carbon-based (graphene and carbon nanostructures) electrode materials are reviewed individually in terms of various neural recording devices that are reported in recent years. Properties of these materials, including electrical properties, mechanical properties, stability, biodegradability/bioresorbability, biocompatibility, and optical properties, and their critical importance to neural recording quality and device capabilities, are discussed. For the packaging and substrate materials, different material properties are desired for the chronic implantation of devices in the complex environment of the body, such as biocompatibility and moisture and gas hermeticity. This review summarizes common solid and soft packaging materials used in a variety of neural interface electrode designs, as well as their packaging performances. Besides, several biopolymers typically applied over the electrode package to reinforce the mechanical rigidity of devices during insertion, or to reduce the immune response and inflammation at the device-tissue interfaces are highlighted. Finally, a benchmark analysis of the discussed materials and an outlook of the future research trends are concluded.

Implantable stimulator failures: causes, outcomes, and solutions

Current designs of implantable stimulators for neuroprostheses exploit trade-offs in power consumption, functionality, volume, selectivity and ease of use. However, no stimulator design should compromise reliability or safety. In this paper, we consider the common failures in implantable stimulators, their causes, outcomes and solutions. A new coding scheme, Manchester non-return-to-zero code, is proposed to format the cable signal in order to avoid prolonged DC current between cable exposures. Thus, in the event of cable failure, the bidirectional charge-balanced current between cable exposures maintains the nearby tissue in safe condition.

A microelectrode/microelectronic hybrid device for brain implantable neuroprosthesis applications

We have designed, fabricated, and characterized a microminiaturized "neuroport" for brain implantable neuroprosthesis applications, using an analog CMOS integrated circuit and a silicon based microelectrode array. An ultra-low power, low-noise CMOS preamplifier array with integral multiplexing was designed to accommodate stringent thermal and electrophysiological requirements for implantation in the brain, and a hybrid integration approach was developed to fabricate a functional microminiaturized neuroprobe device. Measurements showed that our fully scalable 16-channel CMOS amplifier chip had an average gain of 44 dB, bandwidth from 10 Hz to 7.3 kHz, and an equivalent input noise of approximately 9 microVrms with an average power consumption per preamplifier of 52 microW, which is consistent with simulation results. As a proof-of-concept demonstration, we have measured local field potentials from thalamocortical brain slices of rats, showing oscillatory behavior with an amplitude about 0.5 mV and a period ranging 80-120 ms. The results suggest that the hybrid integrated neuroport can form a prime platform for the development of a next level microminiaturized neural interface to the brain in a single implantable unit.