Client: Ken Campbell, Ph.D. Advisor: Glennys Mensing Team Mouse Heart: Michael Kosir Ankur Sharma Steve Trier

Problem Definition To design a device that can rapidly pump saline into a catheter for stiffness measurements during specific intervals in the cardiac cycle. Inject 3 L of saline in less than 5 ms Remove injected portion Stiffness = ∆P/∆V -Already a device to measure ∆P -Need a device to cause a ∆V

Background/Motivation Diastolic Dysfunction: Impaired ventricular filling Decreased stroke volume from LV Greater end-diastolic pressure Cause: Delayed ventricular relaxation and stiffness of ventricular walls Implicated in more than 70% of heart failure patients that are 80+

Design Specifications Inject a fixed quantity (3-5 µl) of saline through a catheter into a left ventricular balloon Operate in less than 5 ms Attach to a catheter with 200 µm diameter opening Must operate with an electrical logic pulse Length of catheter from fluid injector to end of tube is at least 2-3 cm

Design Overview Source: Campbell, 2003

Size Comparison Mouse Heart Catheter: Inserted Into Left Ventrical

Previous Design Circuit Micro Solenoid Valve Pressure Source To Catheter

Previous Design Advantages: Disadvantages: Rapid response time Simple circuitry required Compact Cheap Disadvantages: Less Accurate No Retraction Mechanism

(dVs/dt)ds+P+1/2Vs2+gz=C Flow Analysis (dVs/dt)ds+P+1/2Vs2+gz=C A1V1=A2V2 Unsteady Bernoulli’s Equation and Continuity Principle Cross sectional area of the plunger based on the area of the tubing used 6.0 mm diameter

Piezoelectric Stack Source: Physik Instrumente, Part 239.90

Piezoelectric Stack Sub-millisecond Response High Force Generation 4500 N Push, 500 N Pull Extreme Reliability Max displacement=180 µm High voltage input Maximum operating voltage = -1000 V Cost: $2,940.00

Current Difficulties LEMO to BNC connector on order Current amplifier incompatible Does not handle capacitance of piezo stack Impedance too large Requires a relay controlled by TTL trigger to fire stack Two possible solutions

High Voltage Piezo Amplifier -3 to -1100 V output Up to 50 W peak power 0 to ±11 V control input 50 mA peak output current Designed for use with piezo actuator Source: Physik Instrumente, Part 507.00

Alternate Circuitry 1000V power supply Charge capacitor Acts as voltage supply Close transistor with TTL pulse Capacitor drives piezostack 1000V stack capacitor transistor TTL input

Current Device Source: http://www.physikinstrumente.de

What’s Next Ordering piezo stack parts Fabricating piston and nozzle Syringe Connecting catheter and nozzle Operating on logic pulse Testing

Acknowledgments Ken Campbell Burke O’Neil Naomi Chesler John Webster Glennys Mensing Machine shop

References Physik Instrumente online tutorial of Piezoelectrics. Available at: http://www.physikinstrumente.de/products/section4/content.php Klabunde, R. (2003). Cardiovascular Physiology Concepts: Diastolic Dysfunction. Retrieved September, 2003, from www.cvphysiology.com/Heart%20Failure.HF006.htm Campbell, K. (2003). Glassey, S., Stockner, A., (2002), HEUI—A New Direction for Diesel Engine Fuel Systems. Developed by Caterpillar Inc. SAE paper (930270). Arnold, C., (2003). Hydraulically-actuated, Electronically-controlled Unit Injectors. The Power Shop Inc., retrieved October, 2003, from www.thepowershop.com/HEUI.htm. Biomedical Technical Support Center. “MicroInjection System”, University of Calgary [Electronic Version] Retrieved September 10, 2003 URL:http://www.ucalgary.ca/md/BTSC/MInj_Sys.htm Parker Hannifin Corporation. “Picospritzer: Operating Manual” [Electronic Version] Retrieved September 16, 2003 URL:http://www.lamers-gmbh.de/picospritzer3.htm “Eppendorf FemtoJet Microinjections System” Northwestern University Cell Imaging facility. [Electronic Version] Retrieved October 6, 2003 URL:http://www.feinberg.northwestern.edu/cif/femtojet.htm “What Is a Solenoid?” Detroit Coil Company. [Electronic Version] Retrieved October 6, 2003 URL: http://www.detroitcoil.com/whatis.htm The Lee Company. Essex, CT. http://www.theleeco.com