Implantable Polyimide Cable for Multichannel High-Data-Rate Neural Recording Microsystems

Abstract

To avoid or minimize postimplantation injury as a result of brain micromotion relative to the skull, a flexible multichannel polyimide (PI) cable was designed and microfabricated for data and power transmission between an intracranial IC recording from a neural probe array and an extracranial IC exchanging power and data wirelessly with an external unit. Surface characteristics, electrical properties, and cytocompatibility of the PI ribbon cable were investigated in this study. Scanning electron microscopic examination and atomic force microscopy analyses showed that the surface of the PI ribbon cable became significantly rougher due to the reactive oxygen ion etching process to open bonding pads. The enhanced surface roughness was also responsible for the increase in wettability and water absorption rate. However, water permeability measurement revealed that the micromachining fabrication process did not meaningfully affect the acceptable water vapor transmission rate of PI. Moreover, electrical properties, such as insertion loss, isolation between channels and data transmission capacity, were assessed for each channel of the PI ribbon cable on the basis of scattering parameter (S-parameter) measurement. Finally, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay and live/dead intracellular staining tests were carried out to evaluate cell behaviors on the PI ribbon cable, indicating that the PI ribbon cable did not have acute cytotoxicity and appeared to be as cytocompatible as blank PI foils.

A Wireless and Batteryless Microsystem with Implantable Grid Electrode/3-Dimensional Probe Array for ECoG and Extracellular Neural Recording in Rats

“…The presented microsystem comprises three typical elements: electrodes, connection cable and signal processing circuitry [9]. Figure 1 presents the system structure design and the application situation using the head-stage and main board in a backpack on a rat.…”

Scalable, Modular Three-Dimensional Silicon Microelectrode Assembly via Electroless Plating

“…For example, awake headfixed extracellular recordings in rodents can utilize probe arrays attached to printed circuit boards with conventional methods such as wirebonding or flip-chip assembly. In contrast, chronic applications may require flexible cables to be used (e.g., as described in [ 20 , 42 , 43 , 44 , 45 ]), although this may dictate a lower channel count due to packaging restrictions. Our goal is to demonstrate methods of creating highly scalable Si based electrode arrays and we accordingly uncouple their design from the packaging choice.…”