disposable drug delivery system
TRANSCRIPT
-
8/3/2019 disposable drug delivery system
1/26
Disposable Drug
Delivery SystemRoss Gerber, Aman GhotraKarim Mahamud, & Prakash Rao
Client: Michael MacDonald, MDDept. of Pediatrics UW Hospital & Clinics
Adv isor : William Murphy, PhDDept. of Biomedical Engineering
-
8/3/2019 disposable drug delivery system
2/26
O utline
BackgroundInsulin, Type I diabetes, drug delivering devices
Problem StatementDesign Constraints, Motivation
Proposed Design Solutions : Reaction PumpMicrofluidic Pump
Motor Driven PumpEvaluation
Future Work
-
8/3/2019 disposable drug delivery system
3/26
BackgroundInsulinProduced in Pancreas
Essential protein for glucoseregulationLow insulin levels can lead to
coma or deathType I Diabetes Autoimmune Disease that stopsinsulin production
Affects children and youngadultsPatients must inject insulinperiodically
-
8/3/2019 disposable drug delivery system
4/26
Background (cont.)
Current InsulinDelivering Devices :
Syringes
Insulin PensInsulin jet injectorsInsulin pumps
Have a small reservoir,syringe, programmablehand padCommonly used by TypeI diabetics
-
8/3/2019 disposable drug delivery system
5/26
Problem Statement
Develop a small, automatic,inexpensive (and possibly disposable)
drug delivery system that can give acontinuous flow of a protein-baseddrug over period of twenty-four hours.
-
8/3/2019 disposable drug delivery system
6/26
Design Constraints
A new insulin drug pump must :Deliver solutions at a constant rate for over aperiod of 8-24 hours at 10-100 L/hr Hold up to 0.5 ml of total solutionNot be bulky or heavyBe cost-efficient (maximum cost : $1000.00)
Be user friendlyBe easily sterilized
-
8/3/2019 disposable drug delivery system
7/26
Motivation
Current insulin pump users are dissatisfied,as they :
Do not provide constant flow rates Are expensive ($5,000-7,500)
-
8/3/2019 disposable drug delivery system
8/26
Design 1 : Reaction Pump
Spring generates force As solid organiccompound dissolves,spring is allowed to workReaction is initiatedwhen glass membrane isbrokenRate of reactiondetermines the rate of delivery
-
8/3/2019 disposable drug delivery system
9/26
Progress of Dissolution
Compoundsbefore reaction
t=0
Compounds atbeginning of
reaction
t=1hr
Compoundsnear end of
reaction
t=8hr
View of diffusion
grate
-
8/3/2019 disposable drug delivery system
10/26
Reaction Pump : Components
Spring (1)Liquid Reactant (2)
Solid Reactant (3)Plunger and Grate (4)Insulin (5)Chamber (6)
Start Pin (7)
-
8/3/2019 disposable drug delivery system
11/26
Reaction Pump : Mechanism
Button (7) is pushed tobrake thin membrane (9)Water layer (2) is exposedto dissolvable organiccompound (3)
As the compound dissolves,it passes through the grate(9) at the top of the plunger (4)
Allows plunger (4) to move
down to push insulin (5) outof chamber (6) into therecipient
-
8/3/2019 disposable drug delivery system
12/26
Reaction Pump : Evaluation
AdvantagesVery smallConstant rate
DisposableNo electronicsEasy to useCan vary amount of insulin delivered byconcentration
DisadvantagesMust determine chemicalreaction
No feedback mechanismInsulin can possibly beforced in if an externalforce is appliedCould fall off
-
8/3/2019 disposable drug delivery system
13/26
Microfluidic System
ComponentsMicro-pump
Reciprocating Displacement type
Passive micro-valveControl Circuit
Can precise and controllable amount of fluid
in the range of L/min mL/min
-
8/3/2019 disposable drug delivery system
14/26
Reciprocating Micropump O peration
Moving surface doespressure work on workingfluid in periodic manner
Force-applying movingsurface deformable plate(pump diaphragm)
Basic components pumpchamber (on 1 side of pumpdiaphragm), actuator mechanism, and 2 passivecheck valves
-
8/3/2019 disposable drug delivery system
15/26
Piezoelectric Actuator MechanismPiezoelectric Excitation
If material subjected tomechanical tension,electrical polarizationproportional to extensionwould occur
O pposite also holds true,where material deformationoccurs as a result of applied electric field(inverse piezoelectriceffect)
PZT, Zn OCan be used to benddiaphragm
-
8/3/2019 disposable drug delivery system
16/26
Piezoelectric Actuator Mechanism (cont.)
O perationDriver acts on diaphragm to alternate increase & decrease of pump
chamber volumeFluid drawn into pump chamber during fluid intake stroke (diaphragmexpands), and force out during discharge stroke (diaphragm contracts)Check valves @ inlet and outlet favor bidirectional flow, therebyrectifying the flow over a two-stroke pump cycle
-
8/3/2019 disposable drug delivery system
17/26
Evaluation - Microfluidic Pump
Adva nt ag es
Very small Accurate deliveryWould essentially actas an artificial pancreas
D is adva nt ag es
Too expensive for disposable use
Closed loop feedbackcontrol with glucosesensor is still yearsaway
Very difficult tofabricate
-
8/3/2019 disposable drug delivery system
18/26
Design 3 : Motor Driven Pump
Components :SyringeTubing
Programmable Electronic CircuitPC can change flow rates
A circuit is responsible for converting step and directionsignals into winding energized patterns
Stepping motor Rotates counter-clockwise and clockwiseVariable steps (, , etc.)Smaller steps provide more torque
-
8/3/2019 disposable drug delivery system
19/26
Motor Driven Pump
Components (cont)Converter :
Converts rotationalmotion into linear motionDrives the syringe whichdelivers insulin
-
8/3/2019 disposable drug delivery system
20/26
Evaluation : Motor Driven Pump
AdvantagesInexpensive ($350)Small
SizeEasy to sterilizeProvides constant rate
DisadvantagesNot waterproof
Bathing, swimming
Not effective during mealtimes
-
8/3/2019 disposable drug delivery system
21/26
Decision Matrix
R e ac tion Mi c roflui d ic Motor D ri ven
Cost 4 2 5
Flow Rate 4 4 4
Performance 3 5 4
Size/Appearance 5 4 3
Ease of Use 5 3 4
Programmable 2 4 5
Totals 23 22 25
-
8/3/2019 disposable drug delivery system
22/26
Future Work Motor Driven Pump
Purchase componentsFabricate circuit
Design and produce casingTry to make waterproof Identify feedback mechanism
Minimize size
-
8/3/2019 disposable drug delivery system
23/26
Future Work Reaction Pump
-
8/3/2019 disposable drug delivery system
24/26
Future Work Reaction Pump
Want this to happen as quicklyas possible
A=A0e -kt
-
8/3/2019 disposable drug delivery system
25/26
-
8/3/2019 disposable drug delivery system
26/26
References Adair, T. H. and A. C. Guyton. 1985. Measurement of subcutaneous tissue fluid pressure using a skin cup method. Journal of Applied
Physiology, 58 :1528-1535.Combining Chemistry with O ptics. 2005. The Whitaker Foundation. .Diabetes - The Disorder. 2005. Columbia Encyclopedia. .Haggerty, Michael, et al. Insulin Drug Pump. 27 Dec. 2004. UW-Madison, Dept. of Biomedical Engineering.
.How to Take Insulin. 2005. dlife.com.
.Johnson, Jason. How Stepper Motors Work. 2005. .Jones, Douglas W. Stepping Motor Physics. 2005. University of Iowa - Dept. of Computer Science.
.Laser, D. J. and J. G. Santiago. 2004. A review of micropumps. J Micromech Microengineering 14 :35-64.Liepmann, D., A. P. Pisano, and B. Sage. 1999. Microelectromechanical Systems Technology to Deliver Insulin. Diabetes Technology &
Therapeutics 1 :469-476.MacDonald, Michael M. Personal interview. 26 Jan. 2005.Stepper Motors. 2004. ERNTEC Pty Ltd. .Stepper Motors. 2005. AllMotion Inc. .Tay, F. E. H., W. O . Choong, H. Liu, and G. L. Xu. 2000. An intelligent micro-fluidic system for drug delivery, p. 70-5. I n Anonymous
Proceedings of IEEE International Conference on Industrial Technology 2000, 19-22 Jan. 2000. Jaico Publishing House, Goa,India.
Treating Complications. 2005. The Whitaker Foundation. .what is diabetes? 2005. Juvenile Diabetes Research Foundation International. .