BE211 Lab Agenda • Lab Rules • What is going on in Lab 1 • Overview of EKG and Chapter 9 Bioelectric Measurement • (optional) Stay for common op-amp configuration review / Q&A • (optional) MultiSim Installation for prelab / Q&A Why EKG? • Non-invasive (can be done on each other) • Cardiovascular disease – underlying cause of approximately 50% of deaths in U.S. Heart Anatomy • Two atria – receiving chambers • Two ventricles – pumping chambers • Ventricles have much thicker muscle layer – why? Heart Anatomy • Two atrioventricular (AV) valves – allow blood to flow from atria to ventricles • Two semilunar valves – allow blood to flow from ventricles to major arteries • Heart murmurs caused by leaky valves Cardiac Cycle • Systole – contraction of cardiac muscle in heart chamber • Diastole – relaxation of cardiac muscle in heart chamber Excitable Cells • Only nerve cells and muscle cells are excitable cells • Voltage changes caused by opening gated-ion channels – produces current flow • When muscle cells become electrically excited (stimulated), then they mechanically contract Take home message: spread of electrical activity through heart (cardiac muscle cells) leads to mechanical contraction and pumping of blood Cardiac muscle cells come in two varieties • Pacemaker cells (SA, AV node) – responsible for coordinated spread of electrical activity through heart (autorhythmic); 1% of cells • Contractile cells – responsible for mechanical pumping of blood (create force); 99% of cells. They are ‘electrically coupled’ to each other (neighboring cells) Lead II = Lead I + Lead III (based on KVL) 0 < t < 70ms Time Voltage 70ms < t < 140ms Time Voltage 140ms < t < 200ms Time Voltage 200ms < t < 250ms Time Voltage 250ms < t < 400ms Time Voltage Time Lab 1 • Groups of 2-3 students • Three Parts… • Part I – Instrumentation amplifier (since EKG is differential input signal) • Part II – Bandpass filter • Part III – Fine tuning and digitize signal to MATLAB, calculate BPM Deliverables • Pre-lab simulation using MultiSim • Written calculation of theoretical outcomes • Good practice for circuit construction – Planning, Layout, Neat wiring • Circuit design, evaluation and validation, improvement – along with justification and explanations • Digital lab notebook at the end Chapter 9 Intro… • To the textbook