Disposable Drug Pump Team Cullen Rotroff, Malini Soundarrajan, Kailey Feyereisen, Tyler Allee BME 200/300 October 14, 2005

Client Michael J. MacDonald, M.D. Head, Pediatrics Diabetes and Endocrinology Division Director, Children’s Diabetes Center UW Hospital and Clinics Advisor Professor William L. Murphy, PhD Department of Biomedical Engineering

Problem Statement Alternative method of drug delivery Disposable Small Light Inexpensive Comfortable Discrete while in use

Overview Background on Diabetes and Insulin Competition Design requirements Alternative designs –Hydraulic design –Square wave actuation –Hydrogel Valve and Actuator Future work

Type I Diabetes Background Autoimmune response attacks beta cells in pancreas Beta cells make insulin for body Insulin converts glucose in blood into useable form of energy or glycogen for storage in liver, muscle, or fat High glucose levels cause blurry vision, blindness, nerve damage, kidney failure, heart disease Low glucose can cause weakness, irritability, headaches, and seizures

Insulin Large protein, cannot pass transdermally Can’t be ingested via pills Two necessary delivery forms –Bolus injection Given just after meals and snacks Onset, peak time, and duration –Basal rate Rest of day, basic metabolic needs Our focus for design

Competition Hydrogel Microfluidic Dispenser –Valve actuator interaction –Research phase Microspheres –Slow release capsules –Research phase MiniMed Paradigm 712 –Glucose meter with responsive pump –$6,195

Design Requirements Delivers insulin at a constant flow rate (between micro liters) For use between 8-24 hrs Size of a quarter Disposable Minimal error

Design 1 Fluid driven plunger J-shaped tube Fluid height determined by flow rate from reservoir tube Reliant on Gravity

Design 2 Microprocessor –Powered by 9 V battery –I/O voltage outputs Hydrogel Actuator –Electrically stimulated by electrodes Drug Reservoir –1.2 mL capacity 50 µL/hr flow rate

Design 3 Uses electrically driven Hydrogels –Contracting valve –Expanding actuator Delivers 50-1 µL doses/hr Powered by Parallax BS1 Microprocessor

Future Work Actuating System –Hydrogels Which Ones? Expansion Rate? Surrounding Fluid? –Piezoelectric System Cost? Size? Prototype –Final Dimensions? –How often will it inject How much? –Production –Testing