Disposable Drug Pump

TeamCullen Rotroff, Malini Soundarrajan,

Kailey Feyereisen, Tyler Allee

BME 200/300October 14, 2005

Client Michael J. MacDonald, M.D.

Head, Pediatrics Diabetes and Endocrinology Division

Director, Children’s Diabetes CenterUW Hospital and Clinics

AdvisorProfessor 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 10-50 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