1 / 41

Apparatus for the Analysis of Heart Sounds

Apparatus for the Analysis of Heart Sounds. Team Pacemaker. Luke Philips, Ryan Laterza, Min Dong Bian, Sarah Makhija. Electronic Stethoscope/EKG Device In collaboration with Mechanical and Software Engineering students Dr. Howard D. Weinberger

giulia
Download Presentation

Apparatus for the Analysis of Heart Sounds

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. Apparatus for the Analysis of Heart Sounds PDR – Apparatus for the Analysis of Heart Sounds

  2. Team Pacemaker Luke Philips, Ryan Laterza, Min Dong Bian, Sarah Makhija • Electronic Stethoscope/EKG Device • In collaboration with Mechanical and Software Engineering students • Dr. Howard D. Weinberger • Cardiologist and Co-Director of Cardiac Imaging at the University of Colorado at Denver and Health Sciences Center • Apparatus and methods for analyzing heart sounds • Patent #5,687,738 PDR – Apparatus for the Analysis of Heart Sounds

  3. Project Objectives • Provide objective means of analyzing cardiac acoustics • Aid in diagnosis of heart murmurs • Amplified signal from stethoscope, EKG • Handheld device, portable memory, graphical display PDR – Apparatus for the Analysis of Heart Sounds

  4. Heart Physiology and Anatomy PDR – Apparatus for the Analysis of Heart Sounds

  5. Heart Murmur Pathology • Heart valve(s) fail to close/open properly, causing turbulent blood through the blood vessels • Turbulent blood flow causes high and low pitch sounds known as heart murmurs • Heart problems caused by the malfunction of heart valves Estimates for 2003: 71,300,000 Americans have one or more forms of cardiovascular disease (CVD) PDR – Apparatus for the Analysis of Heart Sounds

  6. Use Case Diagram PDR – Apparatus for the Analysis of Heart Sounds

  7. Heart Rate and EKG Monitor Using Bypass Capacitors and differential amplifier PDR – Apparatus for the Analysis of Heart Sounds

  8. What is an EKG? • Graphic tracing of the voltage generated by the cardiac or heart muscle during a heartbeat • EKG waveform: PDR – Apparatus for the Analysis of Heart Sounds

  9. Circuit Design Problem • Electrical signal is very small: 1mv peak-peak • The signal is noisy • Solution: • Use differential amplifier and bypass capacitors to design the circuits PDR – Apparatus for the Analysis of Heart Sounds

  10. Function • In this case, differential amplifier will reduce the noise voltages • Bypass capacitors help filter the electrical noise out of our circuit,the good default value for bypass capacitors is 0.1uF PDR – Apparatus for the Analysis of Heart Sounds

  11. The EKG Amplifier Circuit PDR – Apparatus for the Analysis of Heart Sounds

  12. Output of EKG PDR – Apparatus for the Analysis of Heart Sounds

  13. The output of EKG after modified circuit PDR – Apparatus for the Analysis of Heart Sounds

  14. How to store these data? • Use Secure Digital Card (SD) • Two sizes: Regular, 32 × 24 × 2.1 mm Mini, 20 x 21.5 x 1.4 mm • Capacity: • Regular, 128, 256, and 512 MBs, 1, 2 and 4 GBs. • Mini, 16MB to 2GB PDR – Apparatus for the Analysis of Heart Sounds

  15. PDR – Apparatus for the Analysis of Heart Sounds

  16. Image of Mini SD Card PDR – Apparatus for the Analysis of Heart Sounds

  17. Mixed Signal Microcontroller Texas Instrument MSP430F427 PDR – Apparatus for the Analysis of Heart Sounds

  18. Key Features • Supply Voltage Range 2.7 to 3.6 Volts (Three 16-Bit ADCs Active) • Scalable Processor Frequency: 6Mhz (2.7 V) to 8Mhz (3.6 V) • Ultra low-Power Consumption: • Active Mode: 400 µA at 1 MHz, 3.0 V • Standby Mode: 1.6 µA • Off Mode (RAM Retention): 0.1 µA PDR – Apparatus for the Analysis of Heart Sounds

  19. Key Features (cont.) • 6 µs Wake-Up From Standby Mode • 16-Bit RISC Architecture • 12 General Purpose 16-Bit Registers • 32 kB of FLASH Program Memory • 1 kB of Random Access Memory • Direct Memory Access Controller • Three Independent 16-Bit Sigma-Delta A/D Converters PDR – Apparatus for the Analysis of Heart Sounds

  20. Key Features (cont.) • One 16-Bit Timer and Two 8-Bit Timers • Integrated LCD Driver for 128 Segments • Serial Communication Interface (USART), Asynchronous UART or Synchronous SPI • Flash Memory can be Programmed by JTAG Port, Bootstrap Loader, or In-System by the CPU • Brownout Detector • Instruction Set Consists of Fifty-One Instructions • Can Operate on Word and Byte • Seven Address Modes PDR – Apparatus for the Analysis of Heart Sounds

  21. TI MSP430F427 Pin Layout and Chip Dimensions 64 Pin Quad Flat Pack Chip 12.2 mm 12.2 mm PDR – Apparatus for the Analysis of Heart Sounds

  22. Analog To Digital Converters 16-Bit Sigma Delta ADC • Sampling Frequencies • Low Power Mode Disabled • 1Mhz • Low Power Mode Enabled • 500Khz • Analog Input Range with Gain = 1 • ±500mV and 650 to 950 uA • Gain = 1 has highest Signal to Noise Distortion Ratio • Input Impedance = 200 kΩ PDR – Apparatus for the Analysis of Heart Sounds

  23. Power • Li-Ion Battery Charger solution using the MSP430 PDR – Apparatus for the Analysis of Heart Sounds

  24. Li-Ion ideal for portable applications High capacity-to-size ratio low self discharge characteristic. Battery charging power management ICs MCU controlled logic devices MCU controlled safe charging time efficient low cost Li-lon battery Features PDR – Apparatus for the Analysis of Heart Sounds

  25. Battery Features (cont.) • Battery capacity, C, mA hours • Battery current, C-Rate • 500 mA-h battery, C-Rate 500mA • 1C, 500 mA • 0.1C is 50 mA. • Li-Ion battery charging, three stages: • Slow Charge: current of 0.1C • Fast Charge: current of 1C • Constant voltage PDR – Apparatus for the Analysis of Heart Sounds

  26. Current vs Voltage for Li-lon Battery Charging PDR – Apparatus for the Analysis of Heart Sounds

  27. Risks of Li-Ion batteries • explosion due to outgassing of electrolyte • Severe reduction in battery life • sensitive to overcharging • final voltage, ±50 mV of 4.1 or 4.2V. • Fully charged • constant voltage, current 0.1C • Observe temperature • safe timing method • charging time longer than a predetermined time Typical Cell Phone Li-Ion batteries rated at ~850 mAh PDR – Apparatus for the Analysis of Heart Sounds

  28. PDR – Apparatus for the Analysis of Heart Sounds

  29. buck converter constant current, constant voltage step down voltage converter inductor as a current source output load impedance, i.e. the battery PNP and NPN transistors switch via PWM switch closed current flows through inductor capacitor is charged switch open inductor maintain current flow Inducing voltage current flows through diode inductor charges capacitor LC network low-pass filter PWM frequency > cut-off capacitor voltage is constant equal to the mean value of input voltage to buck converter PDR – Apparatus for the Analysis of Heart Sounds

  30. Inductor at 75 mH is sufficient • PWM 15 kHz • PWM resolution 8-bits • Capacitor is 220 mF, cutoff frequency of LC network 1.2 kHz • helps capacitor reduce the output voltage ripple • maintain DC voltage level • Three channels on A/D converter on MSP430 to measure battery • battery voltage • battery temperature • battery current PDR – Apparatus for the Analysis of Heart Sounds

  31. Power • Thermistor connected to negative pole of battery • resistance decreases with temperature and thermistor voltage • Risk of design • Complex • Fall back plan • Alkaline batteries • Bench Power PDR – Apparatus for the Analysis of Heart Sounds

  32. Ultralow-Power Keypad Interface With the MSP430 draws 0.1 µA waiting interrupt driven no polling Max 2 µA at 3 V if all keys are pressed and held simultaneously No crystal required Minimum external components Suitable for any MSP430 device Device UI - Keypad PDR – Apparatus for the Analysis of Heart Sounds

  33. Device UI - Keypad • Normal mode • wait-for-press mode • rows driven high • column pins as inputs • interrupt on a rising edge • 4.7 MΩ pull down resistors • inputs low • MSP430 low-power mode • MSP430 current consumption 100 nA. • Maintained indefinitely until key is pressed PDR – Apparatus for the Analysis of Heart Sounds

  34. PDR – Apparatus for the Analysis of Heart Sounds

  35. Device UI - Keypad • Risk of design • Moderate Complexity • Fall back plan • Individual hard-wired buttons PDR – Apparatus for the Analysis of Heart Sounds

  36. Use Case Diagram Revisited PDR – Apparatus for the Analysis of Heart Sounds

  37. Improvement upon current methods • Range of human ear: 20 – 20kHz • May be important info beyond audible range • Objective teaching tool • Time-saving • More accurate medical records and diagnoses PDR – Apparatus for the Analysis of Heart Sounds

  38. Possible extensions • Diagnostic software • Analyze dependence on respiratory phase • Integrate EKG leads and stethoscope • Input patient data from computer rather than keypad • Barcodes PDR – Apparatus for the Analysis of Heart Sounds

  39. Division of Labor • Luke – Design power source, user-interface • Ryan – Systems integration leader, implement microcontroller • Min Dong – Design of memory stick, EKG amplifier • Sarah – Team lead, assist team in technical undertakings • All – Write user’s manual PDR – Apparatus for the Analysis of Heart Sounds

  40. Schedule PDR – Apparatus for the Analysis of Heart Sounds

  41. Thank you! Questions? PDR – Apparatus for the Analysis of Heart Sounds

More Related