Bioelectric Phenomenon & Neural Engineering Lecture Notes PDF

Bioelectric Phenomenon & Neural 04.02.2023 Engineering Unit 2 - Bioelectric Phenomenon & Neural...

Bioelectric Phenomenon & Neural 04.02.2023 Engineering Unit 2 - Bioelectric Phenomenon & Neural Engineering Dr. Soumya R. Mohapatra Author Division Introduction to Bioelectricity 04-Feb-23 | Page2 Bioelectricity has its origin in the voltage differences present between the inside and outside of cells. These potentials arise from the specialized properties of the cell membrane, which separates the intracellular from the extracellular volume. membranes are the site of the electrically active elements — pumps, channels, and connexons joining cells — that create the voltages and currents that cause electrical events to occur. 04-Feb-23 | Dr. Soumya R. Mohapatra 2 Dr. Soumya Ranjan Mohapatra, Asst Prof, KIIT-DU 1 Bioelectric Phenomenon & Neural 04.02.2023 Engineering Author Division 04-Feb-23 | Page3 04-Feb-23 | Dr. Soumya R. Mohapatra 3 Author Division Action Potentials 04-Feb-23 | Page4 Membranes create action potentials by actively changing their permeability to ions such as sodium and potassium. The change of permeability from resting to excited (polarized to depolarized) values and then back again allows the membrane to generate an action potential. 04-Feb-23 | Dr. Soumya R. Mohapatra 4 Dr. Soumya Ranjan Mohapatra, Asst Prof, KIIT-DU 2 Bioelectric Phenomenon & Neural 04.02.2023 Engineering Author Division Action Potential 04-Feb-23 | Page5 An action potential is characterized by a depolarization, which typically results in an overshoot, beyond the 0 mV level followed by repolarization. Some cells may actually hyperpolarize before returning to the resting potential. 04-Feb-23 | Dr. Soumya R. Mohapatra 5 Author Division Threshold 04-Feb-23 | Page6 Action potential initiation has a threshold behaviour. That is, stimuli producing transmembrane voltages above a threshold value initiate action potentials, while those below do not. This response is called “all or none” The threshold value for a particular stimulus varies depending on factors such as the location of the electrodes relative to the tissue that is excited, the stimulus duration, and the amount of membrane affected. 04-Feb-23 | Dr. Soumya R. Mohapatra 6 Dr. Soumya Ranjan Mohapatra, Asst Prof, KIIT-DU 3 Bioelectric Phenomenon & Neural 04.02.2023 Engineering Author Division Basic Elements of an Electrical Circuit 04-Feb-23 | Page7 A. Conductance (G): B. Resistance (R): Resistor C. Capacitance (C): Capacitor D. Battery: 04-Feb-23 | Dr. Soumya R. Mohapatra 7 Author Division Basic Elements of an Electrical Circuit 04-Feb-23 | Page8 A. Conductance (G): B. Resistance (R): Resistor C. Capacitance (C): Capacitor D. Battery: 04-Feb-23 | Dr. Soumya R. Mohapatra 8 Dr. Soumya Ranjan Mohapatra, Asst Prof, KIIT-DU 4 Bioelectric Phenomenon & Neural 04.02.2023 Engineering Author Division 04-Feb-23 | Page9 Equivalent Circuit Model for the Cell Membrane 1. Most cells have a low internal concentration of sodium (Na+) and a high internal concentration of potassium (K+) ions while the external concentrations are reversed. 2. Sodium and potassium channels allow these ions to run down their 3. This electrical activity can be represented by an equivalent circuit electrochemical gradients shown to the left. while ion pumps can The cell membrane capacitance is pump these ions against represented by the capacitor their respective Cm and the various ionic currents are electrochemical added together into a single nonlinear gradients. element through which the current/ion passes. 04-Feb-23 | Dr. Soumya R. Mohapatra 9 Author Division Draw the Equivalent Circuit Model for a Cell Membrane 04-Feb-23 | Page10 04-Feb-23 | Dr. Soumya R. Mohapatra 10 Dr. Soumya Ranjan Mohapatra, Asst Prof, KIIT-DU 5 Bioelectric Phenomenon & Neural 04.02.2023 Engineering Author Division Draw the Equivalent Circuit Model for a Cell Membrane 04-Feb-23 | Page11 04-Feb-23 | Dr. Soumya R. Mohapatra 11 Author Division Donnan Equilibrium 04-Feb-23 | Page12 Donnan Equilibrium in a defined space: = Space Charge Neutrality: Sum of all charges in a defined space is zero. Law of Conservation of Mass 04-Feb-23 | Dr. Soumya R. Mohapatra 12 Dr. Soumya Ranjan Mohapatra, Asst Prof, KIIT-DU 6 Bioelectric Phenomenon & Neural 04.02.2023 Engineering Author Division Problem on Donnan Equilibrium 04-Feb-23 | Page13 A membrane is permeable to K+ and Cl- but not to a large cation R+. Find the steady state concentrations for the following conditions. 04-Feb-23 | Dr. Soumya R. Mohapatra 13 Author Division Biopotential Measurements 04-Feb-23 | Page14 Measurement of electric potentials at the body surface which are indicators of physiological phenomenon such as neural or cardiac conduction. Typically ranging between 1 μV and 100 mV Signal acquisition at Electrode – Skin Interface maybe by Impedance Coupling Capacitance Coupling 04-Feb-23 | Dr. Soumya R. Mohapatra 14 Dr. Soumya Ranjan Mohapatra, Asst Prof, KIIT-DU 7 Bioelectric Phenomenon & Neural 04.02.2023 Engineering Author Division Electrolyte – Electrode Interface 04-Feb-23 | Page15 Charge distribution occurs due to ion-electron exchange at the interface. This gives rise to half cell potential. 04-Feb-23 | Dr. Soumya R. Mohapatra 15 Author Division 04-Feb-23 | Page16 04-Feb-23 | Dr. Soumya R. Mohapatra 16 Dr. Soumya Ranjan Mohapatra, Asst Prof, KIIT-DU 8 Bioelectric Phenomenon & Neural 04.02.2023 Engineering Author Division Types of Electrodes 04-Feb-23 | Page17 Perfectly Polarizable Electrodes These are electrodes in which no actual charge crosses the electrode - electrolyte interface when a current is applied. The current across the interface is a displacement current and the electrode behaves like a capacitor. Example : Platinum Electrode (Noble metal) Perfectly Non-Polarizable Electrode These are electrodes where current passes freely across the electrode – electrolyte interface, requiring no energy to make the transition. These electrodes see no overpotentials. Example : Ag/AgCl electrode 04-Feb-23 | Dr. Soumya R. Mohapatra 17 Author Division If two electrodes of the same metal are placed in solution, a large 04-Feb-23 | Page18 fluctuating potential may exist between the electrodes, because of a small amount of contaminant on one or both electrodes. 04-Feb-23 | Dr. Soumya R. Mohapatra 18 Dr. Soumya Ranjan Mohapatra, Asst Prof, KIIT-DU 9 Bioelectric Phenomenon & Neural 04.02.2023 Engineering Author Division 04-Feb-23 | Page19 Electrode Impedance 04-Feb-23 | Dr. Soumya R. Mohapatra 19 Author Division Recording biopotential from the skin surface 04-Feb-23 | Page20 The fields generated by activity in excitable tissues (nerves or muscles) in the body can spread through the aqueous environment inside the body to appear at the skin surface. Electrodes placed on the skin can detect these potentials. Electrodes are coupled to the skin via an electrolyte – either sweat or an electrolyte solution applied between the electrode and skin. 04-Feb-23 | Dr. Soumya R. Mohapatra 20 Dr. Soumya Ranjan Mohapatra, Asst Prof, KIIT-DU 10 Bioelectric Phenomenon & Neural 04.02.2023 Engineering Author Division Recording biopotential from the skin surface 04-Feb-23 | Page21 04-Feb-23 | Dr. Soumya R. Mohapatra 21 Author Division Principles of Electrocardiography 04-Feb-23 | Page22 The electrocardiogram (ECG) is the recording on the body surface of the electrical activity generated by the heart In order to record an ECG waveform, a differential recording between two points on the body are made. Traditionally each differential recording is referred to as a lead. three leads numbered with the Roman numerals I, II, and III. They are defined as: I = VLA − VRA II = VLL − VRA III = VLL − VLA where RA = right arm, LA = left arm, LL = left leg. 04-Feb-23 | Dr. Soumya R. Mohapatra 22 Dr. Soumya Ranjan Mohapatra, Asst Prof, KIIT-DU 11 Bioelectric Phenomenon & Neural 04.02.2023 Engineering Author Division 04-Feb-23 | Page23 04-Feb-23 | Dr. Soumya R. Mohapatra 23 Author Division 04-Feb-23 | Page24 04-Feb-23 | Dr. Soumya R. Mohapatra 24 Dr. Soumya Ranjan Mohapatra, Asst Prof, KIIT-DU 12 Bioelectric Phenomenon & Neural 04.02.2023 Engineering Author Division ECG Electrodes 04-Feb-23 | Page25 04-Feb-23 | Dr. Soumya R. Mohapatra 25 Author Division Electrode Placement 04-Feb-23 | Page26 04-Feb-23 | Dr. Soumya R. Mohapatra 26 Dr. Soumya Ranjan Mohapatra, Asst Prof, KIIT-DU 13 Bioelectric Phenomenon & Neural 04.02.2023 Engineering Author Division Cardiac Electrophysiology 04-Feb-23 | Page27 04-Feb-23 | Dr. Soumya R. Mohapatra 27 Author Division 04-Feb-23 | Page28 04-Feb-23 | Dr. Soumya R. Mohapatra 28 Dr. Soumya Ranjan Mohapatra, Asst Prof, KIIT-DU 14 Bioelectric Phenomenon & Neural 04.02.2023 Engineering Author Division Principles of Electroencephalography 04-Feb-23 | Page29 The EEG is the recording on the head scalp surface of the electrical activity generated by the brain, where pyramidal neurons act as electrical dipoles. Applications – Diagnosis of Epileptic Seizures 04-Feb-23 | Dr. Soumya R. Mohapatra 29 Author Division Types of Brain Waves 04-Feb-23 | Page30 1. Alpha Waves (8- 13 Hz) – Resting and relaxed adults with closed eyes 2. Beta Waves (13- 30 Hz) – Alert and awake Adults 3. Theta Waves (4-8 Hz) - During sleep and in children; abnormal in awake adults 4. Delta Waves (< 4 Hz) – Normal in deep sleep & young babies 04-Feb-23 | Dr. Soumya R. Mohapatra 30 Dr. Soumya Ranjan Mohapatra, Asst Prof, KIIT-DU 15 Bioelectric Phenomenon & Neural 04.02.2023 Engineering Author Division Average Reference Signal 04-Feb-23 | Page31 Method of EEG measurement 04-Feb-23 | Dr. Soumya R. Mohapatra 31 Author Division Electrical Stimulation of the 04-Feb-23 | Page32 Central Nervous System Front. Cell Dev. Biol., 18 August 2020 04-Feb-23 | Dr. Soumya R. Mohapatra 32 Sec. Molecular and Cellular Pathology Volume 8 - 2020 | https://doi.org/10.3389/fcell.2020.00736 Dr. Soumya Ranjan Mohapatra, Asst Prof, KIIT-DU 16 Bioelectric Phenomenon & Neural 04.02.2023 Engineering Author Division Electromagnetic Stimulation of CNS electrical activity 04-Feb-23 | Page33 Nat Commun 4, 2463 (2013). 04-Feb-23 | Dr. Soumya R. Mohapatra 33 https://doi.org/10.1038/ncomms3463 Author Division Future Platforms: Bionic Network of 04-Feb-23 | Page34 Injectable Neural Prosthetic Devices 04-Feb-23 | Dr. Soumya R. Mohapatra 34 Nat Biomed Eng (2021). https://doi.org/10.1038/s41551-021-00732-x Dr. Soumya Ranjan Mohapatra, Asst Prof, KIIT-DU 17 Bioelectric Phenomenon & Neural 04.02.2023 Engineering Author Division 04-Feb-23 | Page35 Human Machine Interface 04-Feb-23 | Dr. Soumya R. Mohapatra 35 Front. Neurorobot., Volume 11 - 2017 | https://doi.org/10.3389/fnbot.2017.00059 Dr. Soumya Ranjan Mohapatra, Asst Prof, KIIT-DU 18