Leg Ergometer for Blood Flow Studies Amy Weaver, Cali Roen, Lacey Halfen, Hyungjin Kim BME 201 March 9, 2007

Client:William Schrage Dept. of Kinesiology Advisor:Paul Thompson Dept. of Biological Systems Engineering

Overview Problem statement Background Design requirements Design alternatives Proposed Design Future work

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 Used to determine blood flow to the leg during exercise

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

Background Blood Flow Research Two research questions: 1. What are the neural, metabolic, and vascular signals controlling blood flow at rest and exercise? 2. 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 correlated with obesity, diabetics, and high blood pressure

Background: Existing Devices Current device in use at Mayo Clinic Used part of an exercise bike and a car seat Boot is a rollerblade boot with the toe cut out Device was unreliable, and had variable forces

Background: Existing Devices Cont.

Design Requirements Streamlined and compact with minimal loose parts Minimum lifespan of five years Easily portable (with wheels) 5’ long x 3’ wide Chair positioned at various angles from vertical and 3’ above ground Adjust for people of heights 5’4” to 6’4” Flexible range of motion for full leg extension while kicking

Design Requirements Passive return to rest position of the leg after kicking Set up for right leg testing Wattage (0-100 W) and kick rate (30-60 KPM) output to a laptop through an A/D converter Maintain a constant wattage throughout testing Adjustable force between tests Under $2,000

Design Alternatives: Seat for pateint Reclining Adjustable height “Boot” for foot Straps to hold shoe Adjustable force Wheels for movement Sensors Wattage Kicking rate

Design Alternatives: Gas Spring Shock Force from compression of gas in a cylinder Function of velocity Can be purchased in various sizes with variable force Use a cable, allowing for full range of kicking motion Disadvantages Springs back to initial position Stainless_Steel_Gas_Springs_/34982/0?fromSpotlight=1

Design Alternatives: One Way Clutch Allows rotation in only one direction When clutch locks, friction device is engaged When foot is returning, clutch freely rotates Clutch attached to boot by a bar with ball joints extbook/DataFiles/Appendix-B/Appendix-B.html

Design Alternatives: with Drum Brake Shoes push out against drum providing friction Force is constant Adjustable by altering force normal to drum Disadvantages Properties change with heat Brake pedals need to be replaced brake.htm/printable

Proposed Design: with Viscous Friction Viscous friction for force against kick Two pieces of metal with liquid between Force = μ*A*v / t Force altered by changing area Force remains constant through minor temperature changes Rotating Axle spring02/Viscosity.htm

Design Matrix Weight Gas Spring Shock One Way Clutch w/ viscous friction One Way Clutch w/ Drum Brake Overall Reliability Ease to Construct510.8 Maintenance Required Ease of Use Consistent Force Flexible Kicking Motion Passive Kicking Return Force Adjustability Total (Out of 100)

Future Work Finalize design Order components Construct design Test and modify

References Maximal Perfusion of Skeletal Muscle in Man (Per Andersen and Bengt Saltin) 1984 Professor Fronczak ADCATS at Brigham Young University 12_6.html 12_6.html