Overview
1 - Welcome to Module Two
2 - Reviewing Basic Aspects of Electrically Exciting the Nervous System
3 - Stepping Through the Processes
4 - The Animation in its Entirety
5 - Electrical Activation of Nerves – The Significance
6 - Electrode and Target Tissue Separation
7 - Neural Prosthesis Technology
8 - The Electrode-Electrolyte Interface
9 - Adding Charge to the Electrode-Electrolyte Interface
Platinum Electron Bands
10 - Rules Governing Electron Transfer
11 - Filling the Energy Bands
12 - Distribution of Energy States within a Metal
13 - Applying a Potential to the Metal
Electron-Transfer Theory
14 - Energy States
15 - Application of an Anodic Current
16 - Reactant Molecules
17 - Donor and Acceptor States
18 - Ferric-Ferrous Redox Couple
19 - Application of a Cathodic Current
20 - Widely Separated Energy States
21 - Raising the Fermi Level with Cathodic Stimulation
22 - Lowering the Fermi Level with Anodic Stimulation
23 - Reviewing Electron Transfer Across a Metal-Electrolyte Interface
The Kinetics of Electron Transfer
24 - Reactant-Reaction-Product Transport
25 - Not all Electron Transfer Processes are Equal
26 - The Butler-Volmer Equation
27 - Current-Overpotential Equation
28 - Illustrating the Butler-Volmer Expression
29 - Insight into the Behavior of an Electrode
30 - Depleting the Reactant
31 - Diffusion Limited Reactant
32 - Applying a Regulated Pulse
33 - Applying a Regulated Pulse – Supplement
Measurements, Electrodes and Cyclic Voltammetry
34 - Making Measurements
35 - Setting Up to Make Potential Measurements
36 - How a Gold Electrode Works
37 - Cyclic Voltammogram and the Electron Transfer Process
38 - Current Plotted as a Function of Potential
39 - Compare the Voltammograms
40 - Cyclic Voltammograms for a Resistor and Capacitor
41 - Cyclic Voltammogram Profile and Reaction Products
42 - Calculating the Amount of Reversible Charge
43 - Calculating the Amount of Reversible Charge, Oxygen Present
44 - Behavior of a Gold Electrode in 1M PBS
45 - Measuring Electron Transfer Under Pulsed Conditions
46 - Hydrogen Evolution
47 - Gold Electrode in Oxygen Saturated PBS
How a Platinum Electrode Works: from Cyclic Voltammetry
48 - Introduction
49 - The i(Ve) Profile of a Platinum Electrode
50 - Exploration of the Platinum i(Ve) Profile
51 - Storage of the Reaction Product on the Surface of the Metal
52 - A Potential Range that Fits with Neural Stimulation
Comparing How a Platinum Electrode Works in Other Electrolytes
53 - Introduction
54 - The CV Profile for Platinum Operating in PBS
55 - Application of the Nernst Equation
56 - CV profile for platinum electrode in phosphate buffered saline
57 - CV profile for platinum electrode in 0.15 M sulfuric acid
58 - Comparing the PBS CV to the sulfuric acid CV
59 - Continuing exploration of the reactants available with PBS
60 - Further comparison of the reactants available with PBS
61 - Concluding thoughts when considering PBS as a test electrolyte
62 - Platinum electrode in deoxygenated sulfuric acid
63 - CV profiles recorded over fifty cycles
64 - CV profiles with sweep limits below the platinum oxidation and oxygen evolution potentials
65 - Maximizing the amount of charge that can be injected in the hydrogen adsorption region
66 - Considering electron transfer processes that occur in a living system
67 - What electron transfer reactions are taking place at OCP?
68 - CV profile illustrating oxygen content closer to that found in a living animal
69 - Concluding thoughts when considering implanting a “cleaned” platinum electrode in a living system
70 - Exploring the unique properties of platinum
71 - Removing electrons from the platinum electrode
72 - Thinking about injecting cathodic and anodic currents
Cyclic Voltammetry Only Tells You What COULD Happen
73 - Understanding the electron transfer processes to build better and safer devices
74 - The Shannon Plot
75 - Finding ways to inject electrical charge without damaging tissues
Stainless Steel as a metal for electrodes
76 - Stainless Steel Electrodes – prologue
77 - Recording electrical signals from contracting muscles
78 - The CWRU Neuroprosthesis Story
79 - Intramuscular Stimulating Electrodes
80 - Tissue Reaction: Peterson Electrode
81 - Tissue Reaction: Memberg Electrode
82 - Stainless Steel Intramuscular Stimulating Electrodes – Tissue Reaction to Stimulation
83 - Tissue Reaction to Imbalanced Stimulation
84 - Monophasic cathodic stimulation at 50 HZ applied to the surface of the brain in a live animal
85 - Stainless steel electrode in a low oxygen electrolyte
86 - Single pulse response for stainless steel electrode
87 - Pre-pulse potential for 10 pulses at 50 Hz
88 - Correlation between electrochemical studies and muscle tissue damage
89 - Plotting the stainless steel data on the Shannon Plot
90 - Pitting Corrosion
91 - The kinetic aspects of pit formation on stainless steel
92 - Correlation of pitting occurrence and sweep rates
93 - Exceeding the “critical corrosion potential”, without causing corrosion
94 - Thinking about stainless steel as a better metal for neural stimulation than platinum
Electron Transfer Processes Occurring on Platinum Under Neural Stimulation Conditions
95 - Balanced Charge Biphasic Pulses
96 - Charge injection under neural stimulation conditions is less than that predicted by cyclic voltammetry
97 - Experiments that lead to suppressing corrosion of platinum
98 - Anodic phase of a cathodic-first charge-balanced biphasic stimulus
99 - Hypothesis: Platinum corrosion occurs, when balanced charge biphasic pulses are applied at charge injection values exceeding k=1.75
100 - Platinum dissolution in oxygenated phosphate buffered saline
101 - Sulfuric acid experiments repeated in rat subcutaneous tissues
102 - Applying charge-imbalanced biphasic stimulus in rat subcutaneous tissue
103 - Summarizing the material we have covered for a 50Hz train of cathodic first, biphasic stimuli applied to a platinum electrode
Platinum Cyclic Voltammogram – From i(Ve) the plot to the Atomic Level
104 - Platinum CV – Changes that occur at the atomic level introduction
105 - Reviewing the Cyclic Voltammogram for a platinum electrode
106 - Let’s begin our journey through the i(Ve) profile
107 - Hydrogen atom adsorption – reversible electron transfer across interface
108 - Diatomic Hydrogen formation – irreversible electron transfer across interface
109 - Hydrogen atom desorption – hydrogen adsorption reversed
110 - Double Layer Discharging – no electron transfer across interface
111 - Platinum and water oxidation – electron transfer across interface
112 - Platinum oxidation – The metal surface undergoes further reorganization by place exchange
113 - Platinum oxidation – The interface potential is increased to a potential just short of oxygen evolution
114 - Platinum Oxide Reduction
115 - A review of the changes that have occurred on the electrode surface