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FLEXIBLE ELECTRONICS VITALS SENSOR

FLEXIBLE ELECTRONICS VITALS SENSOR. Group #15 Matt Frank Russell Geschrey. Introduction.

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FLEXIBLE ELECTRONICS VITALS SENSOR

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  1. FLEXIBLE ELECTRONICS VITALS SENSOR Group #15 Matt Frank Russell Geschrey

  2. Introduction • This project was chosen because of an interest in wireless communication systems, namely BAN's (body area networks) and their recent integration with flexible electronics research here at the University of Illinois. This area of research, if successful, has the potential to greatly change health care and advance the field of bioinformatics. Pictured above: A flexible electronics project created by Rogers Research Group.

  3. Goal The goal is to create a small flexible electronics vitals sensor, about the size of an average bandage, which can measure a person's vitals such as ECG (heart rate), body movement and core body temperature. It will relay this information over the air in real time to a receiver, where it will be displayed in a graph format and stored for later analysis (such as for medical studies).

  4. Benefits • Allows for mobility while still being able to monitor patients. • Less intrusive and more seamlessly integrated into everyday tasks. • Capable of being used where previous rigid devices were unable to operate. • Allows for studies that could not normally be performed with wired devices. • Does not require battery replacement, which means it is reusable and not harmful to the environment.

  5. Design Overview • Major components • PaLFI/Microcontroller Development Board • Power Supply RF harvesting system • Accelerometer • Temperature Sensor • ECG

  6. Design Overview

  7. Design Logic Overview • Once RF power is transmitted via the “battery charge” command, the device will make sensor measurements using the harvested energy continuously until another command is received. All devices wait in their lowest power mode until addressed and turned on by the microcontroller. • When the “MSP access” command is received, the microcontroller will stop measurements, and transmit the latest sensor measurements to the RFID transponder.

  8. PaLFI/Microcontroller Development Kit Requirements Verification Procedure • The Base Station Reader can communicate required commands to the development board in battery-less mode. • With the software and firmware installed for the device, the base station demo program reports a CRC correct after receiving data from the EZ430 PaLFIdevelopment board

  9. Development Board Verification

  10. Supporting Data • The development board’s self test command is able to flash it’s LED’s without a battery. • PaLFI memory can be remotely read and written to without a battery by test code in the microcontroller. This was tested through the RFID demo software command to read the raw transponder memory.

  11. Power Supply System Higher Level Verification Requirements Verification procedure • The diode and DC/DC converter must be able to convert the rectified RF signal from the antenna to a constant 3.3 V DC. • When the battery check confirms the device is in range, a "charge" command will be given and a voltmeter will be used to measure the potential across the capacitor to ensure a voltage of 3.4V with no more than a 10% error.

  12. Power Supply System Quantitative Verification At a distance of 1 cm, we see that the time constant of the capacitor is 290ms.

  13. Power Supply System Quantitative Verification At a distance of 4 cm, we see that the time constant of the capacitor is 236ms.

  14. Power Supply System Quantitative Verification Currently, measurements are being taken, alternating every 200ms.

  15. Power Supply System Quantitative Verification One measurement takes a maximum of 2.4ms, with a maximum voltage drop of 200mV.

  16. Accelerometer Higher Level Verification Requirements Verification Procedure • The sensor must be able to determine the acceleration within 10% accuracy and transmit the data along the I2c bus • Test by recording data over time when accelerating the sensor. Be sure the time, magnitude, and direction of the acceleration reported is accurate.

  17. Accelerometer Verification

  18. Temperature Sensor Higher Level Verification Requirements Verification Procedure • The sensor must be able to determine the temperature within 10% accuracy and transmit the data along the I2c Bus • Test by recording data over time when changing the temperature using a soldering iron. Be sure the time and magnitude of the temperature data reported is accurate.

  19. Temperature sensor verification

  20. Distance and reliability

  21. Testing Results • Using the RF harvesting and capacitor storage to power the sensor system, the same distances of communication and reliability were possible as the datasheet indicates for an unloaded RFID transponder. • Reliability was 87% over 100 measurements at 4cm distance.

  22. Failed Verifications • Due to time constraints, we were unable to successfully solder, mount and test ECG. • Communication with the RFID reader over USB was not possible due to lack of software support for this device.

  23. Future work • Development of ECG sensor • PCB development and mounting • Embedded software to interface with USB reader directly (as compared to the current GUI script method currently employed). • Purchase and test of a high power reader • Development of hardware on flexible substrate.

  24. Questions?

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