Traumatic Brain Injury Eyewear “TB-Eye”

1. Traumatic Brain Injury Eyewear “TB-Eye” Todd Biesiadecki, Matthew Campbell, Matthew Vildzius ECE4007 L03 EM1 Advisor: Erick Maxwell December 14, 2011

2. Overview • Glasses to alert user of potential head injury • Approximately 50,000 people die and 85,000 suffer long term injuries due to Traumatic Brain Injury(TBI) per year • For non-contact sports such as skiing and cycling • Head impacts infrequent • specialized helmets not justified or practical • Unit development cost: $234

3. Design Objectives • Lightweight, unobtrusive device • Battery powered • Data recording and storage • Wireless communication • Alert the user to get medical attention • Computer based graphical interface

4. Design Goals

5. Device mounted on a pair of sunglasses

8. TB-Eye System-Level Diagram

9. Device Operation

10. Physical Dimensions • Size: • Main Board: 3.4” long • Power Board: 1.45” long • Weight: 14.5 g • With Glasses: 46.2 g

11. Accelerometer • 16G accelerometer • Analog Devices ADXL345 • 145uA max. current • Measurements of 10G or more will trigger an alert • Utility of recorded data more limited vs. full range device • Using built-in interrupts for threshold and data ready

12. Microcontroller • ATMega328 microcontroller with Arduino libraries • Power consumption slightly higher than competition • Well-supported libraries • Power consumption is 4mA while sampling

13. Bluetooth Transceiver • Acts as a cable replacement between device and computer • Only sends data when requested by GUI • ANT wireless protocol difficult to work with, BLE not yet available • Increased size • led to delay

14. Microcontroller Flowchart

15. Saving Serial Data • Python script • No standalone programs available • Difficulties with serial functions in MATLAB • Read binary data from the Bluetooth serial port • Format data as floating points in terms of g • Save data to a text file to be read by MATLAB • Called using the “Read Data From Device” button in GUI

16. Graphical User Interface (GUI)

17. Integration with Glasses • Not allowed to modify given glasses for prototype • Prototype board is larger than desired • In production the circuit could be molded into the glasses frame

18. Battery Life in Monitoring Mode • 110mAh battery • Microcontroller: 4mA max • Accelerometer: 0.15mA • Max current: 4.15mA • Worst-case battery life: 26 hours • Optimization could not be completed in time for demo • Slight additional power reduction should be possible • Notification LED adds additional 2mA • Peak of 45mA when Bluetooth is transmitting

19. Acceptance Testing • Device placed on simulated head • Impact head with calibrated amount of force • Short impact similar to those expected to cause TBI • Used GUI to wirelessly receive, display data • Compare measured data to calibrated impact • Demonstrated LED turns on when threshold is exceeded

20. Prototype PCB problems • Problems getting microcontroller to work (power, wrong frequency, wrong way of programming bootloader) • Resolved with third microcontroller • Bluetooth must be temporarily disconnected for programming

21. Final Budget • Total budget: $405.00 • Total spent: $234 • Expenditures: • Development: $69.85 • Components for one board: $45.94 + PCB ($33) = $78.94 • Unused parts: $85.21 • Spare capacitors, resistors, etc. • ANT modules • Alternate EEPROM module • Oakley M-Frame MSRP: $129.00

22. Future Work • Use ±100g accelerometer for full TBI detection • Low cost size reduction: • Use 4 or more layer board technology • Thinner PCB • Use 0402 and resistors and capacitors, QFN MCU • Eliminate headers, use smaller headers • High cost: Custom integrated circuits • Better integration with glasses frame • Method to more securely attach to the head • Smartphone application

23. Questions?