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Background: Blood Flow Research. Measure blood flow in femoral artery Examine how smaller blood vessels regulate upstream (femoral) blood flow Infuse drugs into the femoral artery. Two Research Questions.
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Background: Blood Flow Research • Measure blood flow in femoral artery • Examine how smaller blood vessels regulate upstream (femoral) blood flow • Infuse drugs into the femoral artery
Two Research Questions • What are the neural, metabolic, and vascular signals controlling blood flow at rest and exercise? • How do conditions like aging and cardiovascular diseases (obesity, high blood pressure, etc) alter the regulation of blood flow?
Wider Implications • Understanding blood pressure control • Correlation with obesity, diabetics, and high blood pressure
Problem Statement • Test subject will use the ergometer to maintain a constant kicking motion • Leg must passively return to original position • Femoral artery is imaged using an ultrasound • Ergometer used to determine blood flow to the leg during exercise
Background: Existing Devices • Current device in use at Mayo Clinic • Made of: • Exercise bike • Car seat • Rollerblade boot • Unreliable, variable forces • Other types of ergometers • Used in rehabilitation • Exercise bikes • Ellipticals
Design Requirements • Streamlined and compact • Minimum lifespan of five years • Easily portable • 5’ long x 3’ wide maximum • Chair positioned at various angles from vertical • Chair ~3’ above ground • Adjust for people of heights 5’4” to 6’4” • Wattage (0-100 W) and kick rate (30-60 KPM) output to a laptop through an A/D converter
Design Requirements • Maintain a constant wattage throughout testing • Adjustable force between tests • Set up for right leg testing • Boot to attach to patient foot • Flexible range of motion for full leg extension while kicking • Passive return to rest position of the leg after kicking • Under $2,000
Design Progress: • Frame • Iron plumbing pipes provide sturdy frame and adjustability • Seat • Car bucket seat reclines and can be moved back and forth • Boot for foot • Snowboard binding allows for multiple foot sizes • Wheels • Allow for ergometer mobility
Design Progress (Cont.): • Bike parts - temporary • Clutch provides one-way motion • Brakes provide variable force • Brakes adjusted by client • Sensors • Hanging scale to sense force prior to beginning of test • Hinges • Hinges and bar to connect boot to bike pedals
Testing Performed • Multiple test subjects • Size, compatibility, kicking pattern • Ten minute test • Strain, Heat of brakes • Variable force test • Strain, Heat of brakes, device stability
Budget Frame……………………..... $110 Chair & Cover……………… $55 Boot…………………………. $50 Bike…………………………. $90 Hardware…………………… $30 Total………………………… $335
Future Work • Implement new friction device • Multiple proposed designs • Build clutch housing • Received clutch from Formsprag Clutch • Research and purchase appropriate sensors • Add handles for test subject comfort • Attach fold-out table for client comfort • Test and modify
Future Work: One Way Clutch • Allows rotation in only one direction • Engages friction device when locked • Rotates freely when leg is returning to original position http://www.mie.utoronto.ca/staff/projects/cleghorn/Textbook/DataFiles/Appendix-B/Appendix-B.html http://adcats.et.byu.edu/WWW/Publication/94-1/Paper1-12_6.html
Future Work: Drum Brake • Shoes push out against drum providing friction • Easily adjustable Disadvantages • Force varies with temperature • Brake pedals require maintenance http://www.howstuffworks.com/drum-brake.htm/printable
Rotating Axle Future Work: Viscous Friction • Viscous friction for force against kick • Two pieces of metal with liquid between • Force remains constant through minor temperature changes Disadvantages: • Unable to find a model which provides the necessary torque http://galileo.phys.virginia.edu/classes/152.mf1i.spring02/Viscosity.htm
References: • Maximal Perfusion of Skeletal Muscle in Man (Per Andersen and Bengt Saltin) 1984 • ADCATS at Brigham Young University http://adcats.et.byu.edu/WWW/Publication/94-1/Paper1-12_6.html • www.sugatsune.net • www.acecontrols.com
Additional Thanks To: • Professor Frank Fronczak • Department of Mechanical Engineering • Mike Travis – Formsprag Clutch • Yashpal Subedi • Paul Tutabelli – Taylor Devices