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ECG Project

ECG Project. By Lambda Team Anthony Shelton Jonathan Killen Quintelle Griggs Chan Hauw Ki. ECG Heart Monitor. Use for high-risk heart attack patients Have electrodes on patients Have patients wear device. Differential Amplifiers. A/D Converter. Microprocessor.

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ECG Project

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  1. ECG Project By Lambda Team Anthony Shelton Jonathan Killen Quintelle Griggs Chan Hauw Ki

  2. ECG Heart Monitor • Use for high-risk heart attack patients • Have electrodes on patients • Have patients wear device Differential Amplifiers A/D Converter Microprocessor

  3. Problems Dealt With in the Project • Determine patient’s heart rate when it is below 60 or above 150 beats per minute • Send signal to nearest aid

  4. Probable solutions to problems • Use blue-tooth technology for alerting the caregiver • Display signal of QRS waveform

  5. Inclusions of project • Analysis and Detection of Signal • Use of Differential Amplifiers • Use of Microprocessor • Use of Analog/Digital Converter • Use of Printed Circuit Board

  6. MAX 1240 A/D CONVERTER • Low Power (+2.7V to 3.6V) • Internal 2.5V Reference • Shutdown mode (2microAmps)

  7. MC68HC811E2CFN2

  8. FEATURES of the 68HC811E2 • MC68HC11 CPU • 512 Bytes of On – Chip RAM • 2048 Bytes of EEPROM • Power Saving Stop Mode • 5V Operating Voltage

  9. ELECTRICAL ACTIVITY OF THE HEART PROVIDES: • Heart Rate • Previous heartattacks • Increased thickness of the heart muscle • Signs of decreased oxygen delivery to heart

  10. 2 HEARTBEATS

  11. HEART RATE RATE = 60/(R-R interval)

  12. Determine when new data is available Recognize R-wave of the QRS complex Count the time between the occurrence of 2 R-waves Compute heart rate Determine if heart rate is > or < a specified value Sound an alert depending on heart rate SUMMARY OF CODE TO ANALYZE DATA

  13. Instrumentation Amplifier Stage Instrumentation Amplifier A/D Converter Microprocessor

  14. What we have: EKG signal (5 mV range) What we need for the A/D converter: Signal range of 2.5V Frequency range from 0.18 Hz - 160 Hz Common-mode signals rejected Where to start?

  15. Complete Design • Instrumentation Amplifier

  16. Common-mode rejection of 115dB Isolates EKG differential signal that we want Prevents interference from radiated AC (such as the lighting in a room) Gain of 10 MAX 4194 Instrumentation Amplifier

  17. Inside the Instrumentation Amplifier • Two stages of Op-Amps • All the same Resistor values Gain = 1 Gain = 10

  18. Complete Design • Patient Reference

  19. Patient Reference • It is helpful to reference the signal with respect to the patient’s potential (less variation) • Used values recommended for feedback Creates stability Forces the signal to centered around patient’s potential Reference point between voltage sources

  20. Complete Design • Filters

  21. High-Pass Filter Cutoff frequency of 0.18 Hz Low-Pass Filter Cutoff frequency of 160 Hz Filters

  22. Complete Design • 5V Voltage Regulator

  23. Regulate the voltage needed for the A/D Converter and the Microprocessor to operate Also, includes a Low Battery Indicator MAX 666 5V Voltage Regulator

  24. Complete Design • Second Amplification Stage

  25. A/D Converter needs the signal to have a voltage range of 2.5V Need another Op-Amp with a gain of 50 Total gain of 10 X 50 = 500 Amplify more for the A/D

  26. Complete Design • Stop Interrupt

  27. Finally, Stop Interrupt • Used to turn on and off A/D and microP • Creates a digital signal • Resistors set SPS to 500 REF from the A/D = 2.5 V “Sleep” or Stop signal helps conserve power

  28. 5 V 3.75 V 2.5 V … … 1.25 V 0 V Voltage over the Capacitor • Voltage across the capacitor tries to push all the way to 5V and down to GND, but gets flipped. Discharging Charging • This creates the digital signal at the output to turn the A/D and the microP on and off

  29. Power Budget microP : 15mA 100uA A/D: 4mA 10uA 4 Op-Amps: 40uA Inst. Amp: 93uA Voltage Reg.: 12uA Average Load = about 2.2mA @ 10% duty cycle Speaking of power Min Load = about 250uA Max Load = about 20mA

  30. Small & little weight (9grams) Best battery found would last 300 hr (12 ½ days) Is that long enough? What is the best battery to use? Wafer Lithium • Very small & light weight (5grams) • Can not handle our load for more than 5 hr • Not enough time. ½ AA Lithium/Thionyl • Is this the best battery for us?

  31. Big Picture!

  32. Printed Circuit Board

  33. Printed Circuit Board • Need a drilling machine drill the PCBoard. • Holes will be drill according the size of individual component. • Pin size of: • Op-Amp chips • 8-pin SO

  34. Printed Circuit Board Cont. • Pins size continue: • A/D Converter • 8-pin DIP and SO • Microprocessor • 38 General-Purpose I/O pins • 16 Bi-directional I/O Pins • 11 Input-Only Pins • 11 Output-Only Pins

  35. Printed Circuit Board Cont. • Pin size continue: • Microprocessor • 48-Pin Plastic Dual In-Line Package (DIP) • 52-Pin Plastic Leaded Chip Carrier (PLCC)

  36. PSPICE Program • MICROSIM PCBoard program • ISO PRO program • QUICKCAM program

  37. MicroSim PCB Program • First load the drawn schematic file • Three files will be generated: • COMPONENT (Red) • TOP Layer • SOLDER (Red) • BOTTOM Layer • DRILL (Gray) • Drill size

  38. MicroSim PCB Program • Why need three file for drilling: • Double-sided PCB • Next step ISO PRO!

  39. ISO PRO program • Create two layers: • Blue layer (pads, traces) • Green layer (drill holes) • Why need this: • Used to ISOLATE the COMPONENT layer • Outline the pads and traces of design • ISOLATE the copper on the board

  40. QUICKCAM Program • We need: • MIRROR the layer • REGISTER the layer • ISOLATE the layer • EXPORT the layer to the QUICKCAM • Final files the machines reads to mil a circuit board

  41. Summary • Issues on product: • Power • Battery found so far: • Wafer Lithium 5hrs • Lithium/Thionyl 300hrs • Trade off: • Wafer Lithium is smaller but (<1 day) • Lithium/Thionyl bigger but (12 ½ day)

  42. Summary Continue • Serial port interface, from the Bot-Board to the PC Board • Since we haven’t receive the A/D converter • A/D converter to the Microprocessor • Spice model that we haven’t found. (Microprocessor model, A/D Converter Model)

  43. Summary continue • Issues concerns: • Realistic Constraints • Milling machine; OS for the processor assembler is only in Win 95/NT; Limited battery life • Economics • Inexpensive for hospitals to buy

  44. Summary Continue • Environmental Implications • Save energy in order to use less battery • Sustainability • There will always be a need to monitor the heart of people with heart conditions

  45. Summary Continue • Ethical Concerns • IEEE Ethical Standards • Health and Safety • Product does not shock patient; product is comfortable to wear

  46. Summary Continue • Social Concerns • Allows patient more freedom; product is small enough to be discretely worn • Political • There are no political concerns for our device.

  47. Summary Continue • Manufacturity • Estimated cost ($150 Dollars)

  48. Summary Continue

  49. Summary Continue • Finished product would include: • All the devices on the PC Board should operate correct. • Microprocessor, A/D converter, Analog, Programming.

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