Evolution Flashcards
Evolution of ICS
Implantable Cochlear Stimulators
1.0
1.2
CII Bionic Ear
HiRes 90K
HiRes 90K Advantage
ICS Components
Casing/Receiver package Output circuits Capacitors Magnet Custom Chip Bi-Directional Telemetry Electrode array
ICS Casing/Receiver Package
Properties of casing
Materials must be biocompatible (not harmful to the body)
Must be hermetically sealed to prevent internal electronic damage (from body fluids)
2 available materials: ceramic and titanium
ICS Casing
Ceramic vs. Titanium
Ceramic
Good transmission properties
Highly durable, but placement can pose increased risk to case fractures upon direct impact
More drilling required
Antennae and electronics housed within single unit
Titanium
Poor transmission- antenna outside of casing
Due to design change- less drilling required
Smaller in depth
ICS Casing
Which ICS are encased in ceramics?
Which ICS are encased in titanium?
Ceramic
1.0
1.2
CII
Titanium
HiRes 90K
All about output circuits
Current sources
Key feature of our system, allowing for significant flexibility in sound processing
- Allows the capability to stimulate sequentially, partially simultaneously, or fully simultaneously
Output circuits
AB vs. Competitors
C-1: 8 independent output circuits
CII and HiRes 90K: 16 independent output circuits
Cochlear: 1 output circuit (slower and only sequential patterns of stimulation)
Med-El: multiple output circuits (12) but their system employs low transmission rates which doesn’t allow them to stimulate simultaneously
Capacitor and why we need them
Electrical component that holds charge.
Provide protection against leakage of harmful DC current which can damage neural tissue
Capacitor holds any excess charge (+ or -) to ensure that a balanced pulse is delivered to the nerve
Control current leakage and prevent current buildup
Capacitors
AB vs. Competitors
AB
C1 ICS has 8 capacitors
CII and HiRes90K have 16 capacitors
Cochlear
Use shorting mechanism
Med-El
Capacitors
Magnet location
On the center of the substrate (circuit board) with 1.0, 1.2, and CII
Embedded in silicone portion of HiRes 90K, allowing magnet to be removed for MRI application
Custom chip
Microchip located on substrate (circuit board)
Allows capability to sample and deliver incoming signal at fast stimulation rates
CII and HiRes 90K have internal memory: storing internally frees up bandwidth and can deliver more info to the system and increase power efficacy
Bi-Directional Telemetry
Capacity to send information in both directions
Monitors the communication between the internal and external hardware
Essential feature for audible alarms/LED, measuring impedances, and power management
Forward FTEL: 49 MHz
Send data and power to the implant
Back BTEL: 10.7 MHz
Info regarding status of implant
Allows system to continually monitor function
Impedance measurements
Electrode design
Spiral electrode
HiFicus electrode
Differ in:
Wiring of electrode contacts to the stimulus current sources
Location and shape of contacts
Curvature of electrode carrier
Electrode coupling
Monopolar vs. Bipolar
Electrodes stimulated in pairs with one active and one ground electrode
Monopolar
Stimulating/active electrode is intracochlear
Ground electrode extracochlear (I.e., case ground on 90K)
Able to recruit more nerve fibers to obtain adequate loudness levels with less current
Bipolar
Both stimulating/active electrode and ground electrode intracochlear
Stimulate more accurately
Recruits fewer nerve fibers which requires more current to obtain adequate loudness levels
Components of cochlear implant
Internal hardware
Implant
Electrode array
External hardware
Sound processor
Headpiece
Accessories
