1 / 19

Phasors , Capacitors, Impedance

Phasors , Capacitors, Impedance. Spin My World Right Round. LPF Application: Gastric Electrical Activity. 60-70 million people suffer from GI disorder Electrically active organ. http://www.virtualmedicalcentre.com/anatomy/gastrointestinal-system/7.

melinda-dillon
Download Presentation

Phasors , Capacitors, Impedance

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Phasors, Capacitors, Impedance Spin My World Right Round

  2. LPF Application: Gastric Electrical Activity • 60-70 million people suffer from GI disorder • Electrically active organ http://www.virtualmedicalcentre.com/anatomy/gastrointestinal-system/7 Image from P. Du et al. Biophys J. (2010) 99:2784-2792.

  3. Electrogastrogram and Slow Wave mapping Flexible Electrode Array (256 electrodes) Recording the EGG (6 electrodes) Typical gastric slow wave recording (freq ~ 0.05 Hz) Mapping SW activity with high density electrodes

  4. Real life example Signal of interest Noise (oscillations so fast you can’t see the individual waves) What the electrode records (ruh-roh!)

  5. One possible solution: Low Pass Filter Vout(t) • High frequency components: Kill off (strongly attenuate) • Low frequency components: Pass through essentially untouched

  6. LPF in Action Strongly attenuated 60Hz Barely attenuated 0.05Hz

  7. Raw vs. Filtered Signal INPUT OUTPUT (raw gastric + raw powerline) (filtered gastric + raw powerline)

  8. Capacitors come in all shapes and sizes Typical ones in the lab Some big, some small

  9. These are capacitors too! Cell membrane Icky cells (bacteria)

  10. And so is this! PC board Red = top layer Green = bottom layer

  11. Phasors: Magnitude and Phase Projection onto real axis traces out Acos(wt + f)

  12. Magnitude and Phase http://resonanceswavesandfields.blogspot.com/2007/08/phasors.html#phasor-beating

  13. Phasors! -sinwt coswt -coswt sinwt Rotates in time But we just read off the magnitude and phaseinformation at one instant (usually, t = 0)

  14. Raw vs. Filtered Signal (50 kW) (10 mF) We now interrupt this broadcast to do some phasor math…

  15. Implementing a low pass filter (LPF) Strongly attenuated 60Hz Barely attenuated 0.05Hz

  16. 60 Hz signal zoomed in f

  17. Bode Plot power line gastric cutoff

  18. What else is it good for?

  19. Get rid of bieber • Beauty and the Beat • Sweet bass line (f <= 150 Hz) • Screechy Bieber vocals (f >= 450 Hz) • Raw song SNR = Bass/Bieber = ½ • Design a circuit that: • increases SNR >= 1 • keeps phase shift for bass frequencies |f|<= 40 deg.

More Related