GPS-ENABLED ASTHMA INHALERGPS-ENABLED ASTHMA INHALER Michael Alexander | Joseph Cabelka | Mollie Lange | Peter MaMichael Alexander | Joseph Cabelka | Mollie Lange | Peter Ma BME 402BME 402 March 8, 2008March 8, 2008

PROJECT SUPPORTERSPROJECT SUPPORTERS PhD, Medical Anthropology Population Health Sciences, focus in asthma and allergy Epidemic Intelligence Service officer for Centers for Disease Control Special projects with National Asthma Control Program Currently at UW as a Health and Society Scholar Biomedical Engineering Orthopedics and Rehabilitation UW-CREATe Advisor: Professor Mitch Tyler Client: David Van Sickle

CONTENT Problem Statement Background Motivation Design Constraints Design Solution Current Progress Future Work References

PROBLEM STATEMENTPROBLEM STATEMENT Create a device capable of: – Tracking the usage of asthma inhalers – Transferring between medication dispensers – Noting time, date, and location of exacerbations – Wireless transmission of subject data to database

Asthma – Chronic respiratory disease in which airways are blocked due to allergy or inflammation – Over 20 million Americans currently suffer from asthma Global Positioning System (GPS) – First developed for military – Widely used in communication, recreation, and safety – Uses signal transmission time to triangulate position BACKGROUND

PREVIOUS SEMESTERSPREVIOUS SEMESTERS 2nd Generation: Program PIC chip Created PCB Power: Cell phone Li-ion battery Housing case 1st Generation: Proof of concept Not portable Manual command prompt

THIS SEMESTERTHIS SEMESTER Goals/Priorities – Resolve power issues – Packaging (minimize size) – Web integration – Testing

RESOLVING THE POWER ISSUERESOLVING THE POWER ISSUE Li-ion Batteries – Obtained new, high-capacity batteries Can be internal or external to casing Come with connectors that will make charging simple Very low quiescent (non-use) current drain Battery life as a function of robustness – Need to decide how to handle usage issues without draining battery (more details later)

PACKAGING Completed: – New switch to control circuit Considered spring-loaded, momentary, FSR Obtained and tested Force-Sensitive Resistor (next slide) – Miniaturizing Printed Circuit Boards Chose surface-mounted elements to obtain decrease in surface area, depth; reduces chance of short circuits Rerouted pathways to utilize both sides of boards – Made caps w/flat surface to fit medicine canisters

FORCE-SENSITIVE RESISTORS (FSR)FORCE-SENSITIVE RESISTORS (FSR) Advantages – Have the ability to set a threshold that corresponds to desired force – Minimizes false-positives and threshold value can be easily controlled with a voltage divider – Rounded, non-obtrusive design Disadvantages – Need flat (instead of concave) surface – Need to test for best sensitivity ratio

FORCE-SENSITIVE RESISTORS (FSR)FORCE-SENSITIVE RESISTORS (FSR) Researched force required for actuation – Not perfectly standardized but average values are available – Approx force required for medicine to dispense: ~1500g – Set threshold resistance based on documentation for FSR

DEVICE COMPONENTS & TESTINGDEVICE COMPONENTS & TESTING Battery – How long will it last? FSR/PIC Chip – Is it reliable? Wear and tear – Patient use – Weakest component(s) GPS Connection – Can we always get GPS coordinates?

BATTERY Obtain current (I) information – Quiescent – Pinging GPS – Transmitting to website Calculate maximum use time Finalize program – Determines how often our device is in each stage Suggested battery life

FSR/PIC CHIPFSR/PIC CHIP Will pressing the FSR reliably activate the device? – Standard force Reliably activate inhaler – Human finger tests Will using a finger distribute force unevenly enough to not activate the PIC chip?

WEAR AND TEARWEAR AND TEAR Simulate patient use – Patient usage profiles – 7 days Determine the weakest component of device Preliminary test group – Gather data from user questionnaire

LOCATION TESTINGLOCATION TESTING Test indoors – Different floors – Different buildings Test outdoors – Urban environment – Rural environment Compare GPS output with actual coordinates Helps determine how to handle lack of fix

GPS SIGNALGPS SIGNAL Overcoming urban environment – Need to account for lack of satellite signal inside most building – Possibilities: Incorporate code to “wake-up” and get GPS coordinates at set time intervals (dependant on battery). If at time of patient activation, GPS coordinates cannot be retrieved, send reserve coordinates Send coordinates next time it can get signal Send dummy string and ask patient to input location when they log in online – Probably will combine all three to make program as effective as possible

PROGRAMMING Multiple Application Handling – Program distinguishes between single/multiple ascerbations based upon timing GPS Fix Acquisition Profile – Periodic Fix vs. Push to Fix – Event time vs. fix/database time – Affects position accuracy, validity – Parameters to be determined through testing

PRIVACY ISSUES/IRBPRIVACY ISSUES/IRB Robust program – polling frequently – High poll frequency raises issues of “tracking” – Reliability may have to be sacrificed to protect patient privacy Patient information online – Can be set up as normal, blind, or double blind for studies – Patients receive ID number based on device given – Statistics are reported with regard to ID number

REFERENCES Asthma and Allergy Foundation of America American Academy of Allergy Asthma and Immunology Trossen Robotics Community

QUESTIONS? Thank you for your time! Any questions?