1. Biomedical applications of filters and amplifiers

2. http://www.touchbionics.com/products/active-prostheses/i-limb-ultra/

4. http://lowerextremityreview.com/article/unstable-shoe-designs-functional-implications http://www.vibrationtrainingdevice.com/VG-Evolution-I-Vibrogym.htm Skin electrodes Filters and Amplifiers

5. EMG Main Idea 3 total electrodes 1 positioned over an “electrically quiet” place = ground, V g 2 signal electrodes measure potential on muscle relative to ground. Instrumentation amplifier computes the difference: V out = (V 1 – V g ) – (V 2 – V g ) = V 1 – V 2 V1-Vg V2-Vg G (V2-V1)

7. Gain x Bandwidth = constant

8. PROBLEM: SKIN RESISTANCE SOLUTION: OP-AMP BUFFER Voltage lost going across skin: I skin x R skin  Buffer blocks current flow, therefore no voltage lost across skin!  Buffer output voltage “follows” the input Muscle- generated signal Measurement Device

9.  Metal electrode touching skin looks very similar to an electrochemical cell  Unwanted DC offset voltage generated

10. Buffer/Active Electrodes Computer Processing Account for skin/electrode resistance HPF Account for dc offset (“battery”) offset at electrode-skin interface Differential Amplifier Make voltage signal usable to computers that usually require >1V signal LPF Get rid of unwanted high frequency junk

11.  AJ Fridlund and JT Cacippo. Guidelines for Human Electromyographic Research. Pscyhophysiology 23(5) 567- 589, retrieved from: http://www.sprweb.org/articles/Fridlund86.pdf http://www.sprweb.org/articles/Fridlund86.pdf  Intan amplifiers: http://intantech.com/amplifier_intro.htmlhttp://intantech.com/amplifier_intro.html  INA126 http://www.ti.com/lit/ds/symlink/ina126.pdfhttp://www.ti.com/lit/ds/symlink/ina126.pdf  Delsys: delsys.com