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

2. 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. 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. 4 Design Goals SpecificationTargetActual Power Consumption61.67 mW 13.1mW Supply Voltage3.7 V Battery Life1 day of normal operation Battery Capacity400 mAh110 mAh Weight50 g 14.5g/ 46.2g with glasses SizeLess than 4 x 0.6 x 0.2 inches L x W x H 3.4 x 0.7 x 0.35 1.45 x 0.5 x 0.22 Acceleration Range±100g in all three axes±16g in all three axes Acceleration Recording Threshold 10g Acceleration Alert Threshold50g10g Sampling Rate (Idle)2 kHz 3.2KHz Sampling Rate (Active)6 kHz 3.2KHz Wireless Transmission ProtocolANT+Bluetooth Transmission Power0 dBm Transmission Range10m Data StorageStores the value of acceleration and time elapsed since the impact occurred. Stores the value of acceleration GUIDisplays the acceleration data graphically

5. 5 Device mounted on a pair of sunglasses

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8. 8 TB-Eye System-Level Diagram

9. 9 Device Operation

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

11. 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. 12 Microcontroller ATMega328 microcontroller with Arduino libraries –Power consumption slightly higher than competition –Well-supported libraries Power consumption is 4mA while sampling

13. 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. 14 Microcontroller Flowchart

15. 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. 16 Graphical User Interface (GUI)

17. 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. 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. 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. 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. 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. 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. 23 Questions?