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The Design of a Drug Delivery Micro-Device Utilizing the Soft

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									The Design of a Drug
Delivery Micro-Device
Utilizing the Soft
Lithography Process



            Michael Bradway
               Nicole Siems
                Steven Silva
Presentation Overview
•   Project Objective
•   Customer Needs
•   Other Drug Delivery Devices
•   Design Specifications
•   Material & Battery Choices
•   Actuation Mechanisms
•   Preliminary Design
•   Detailed Design
•   Prototype Investigation
•   Cost Estimation
•   Conclusion
Objective
• To use Soft Lithography to
  design a micro-scale device
• Due to inadequate facilities the
  design will be demonstrated on
  the macro-scale
Customer Needs & Function
         Matrix
Norplant
• Implantable birth control system as a
  alternative to the pill
• Uses a non-degradable polymer, called
  Silastic
• Six capsules are inserted
  subcutaneously into the upper arm
  each approximately 34mm long
• Each capsule contains 35 mg of
  levonorgestrel, which permeates the
  Silastic to direclty enter the blood
• Effective for up to 5 years
Implantable Drug
Delivery Micro-chip
• Uses MEMS
  Technology
• Several Micro-
  chambers hold
  one dose of
  medication
• Electrochemical
  reaction
  removes cap off
  of each chamber
Artificial Muscle
• Micro machined chamber
  covered by electrochemically
  activated metal valves
Integrated Drug Delivery
System
• Valve is a
  small pincher
  placed on an
  elastic tube
• Overall size
  50x15mm
• Does not
  utilize soft
  lithography
Extended Release
Capsule




• Once medication is released the
  dosage increases to combat
  tolerances created
• The tablet is coated with a semi
  permeable membrane that
  controls the transport of water
Health Conditions &
Treatments
• Diabetes
• HIV & AIDS
• High Cholesterol
• Allergies
Other Design
Specifications
•   Site of Implantation
•   Overall Size of the Device
•   Shape of the Device
•   Shape of delivery channel
•   Fluid Mechanics Calculations
    – Dimensions of Channel (10 x 100 x 650
      micrometers)
    – Velocity = .00088 m/s
    – ∆Pressure of Channel=58Pa
Material Options
Micro-Fabricated Valves
and Pumps
• Valves are
  created using
  crossed channel
  architecture
• A peristaltic
  pump is possible
  with three
  valves arranged
  on a single
  channel
Hydrogel
• Similar construction as
  the valves and pumps
• Hydrogel is
  polymerized anchored
  to the substrate where
  the channels meet,
  cross points
• The expanding or
  contracting of the gel
  restricts or enables the
  flow rate
Piezoelectric
• Converts
  electrical
  energy into
  mechanical
  energy
• Used as sensors
  or actuators
• Large actuation
  force, but a high
  drive-voltage
Thermo-Mechanic
• Consist of a
  heater,
  diaphragm and
  sealed cavity
• A voltage is
  applied to
  actuate the
  diaphragm
• Generates a
  large amount of
  heat
Electrostatic
• Is actuated by the electrostatic
  attraction force
• The deflection of the diaphragm can
  be easily controlled by the applied
  voltage, and the response time is
  fast
• The output pressure and the volume
  stroke are small compared with
  others because large volume stroke
  requires high voltage input
Electromagnetic
• Similar to the electrostatic
  concept
• More efficient on the macro
  scale rather then the micro
  scale
Decision Matrices
Battery Alternatives
• Lithium Iodine Cells
• Designed to deliver current drains in
  the microampere range
• Reliable over long periods of time
• Wilson Greatbatch Technologies, Inc.
  – Smallest standard is 4mm thick and has
    a nominal capacity of 0.42 ampere hours
• Seiko Instruments Inc. Micro-
  batteries
  – a range of diameters from 4.8 to 9.5 mm,
    height from 1.4 to 2.1 mm, and nominal
    capacity from 0.25 to 8.0 mAh
Preliminary Design
• Reservoir
  – 2,000 μmeters long by
    3,000 μmeters wide
    and 12,500 μmeters tall
• Channel
  – 650 μmeters long by
    100 μmeters wide and
    0 or 10 μmeters tall
• Size of Device
  – 2,700 μmeters long by
    3,100 μmeters wide
    and 12,600 μmeters tall
Schematic Diagram of
Preliminary Design
Assembly Drawing of
Detailed Design
• Addition of 4th
  Valve Set
• Steady state
  channel height =
  10 μmeters
• Device height =
  40,000 μmeters
• Electrostatic Force Generated
  • Fmax =4.8*10-7N   Fmin=4.8x10-19N
Schematic Diagram of
Detailed Design
      • Steady State

      • 4th Valve Opens to release fluid.
      1st Valve Closes to force fluid
      toward exit.
      •2nd Valve closes to force fluid along
      channel to exit.
      •3rd Valve closes to force fluid along
      channel to exit.
      •Returns to Steady State
Prototype Investigation
• Solenoids
• Dow Corning Material Kits
• Product Mold
 – Machine Shop
 – CNC machine
Cost Estimation
Engineering Consulting Firm
Cost Estimation
Engineering Consulting Firm
Cost Estimation
Engineering Economic Design
• Market Analysis
  – 4% of Allergy Sufferers = 4.5 million
    people
• Business Model
• Minimal Acceptable Rate of Return =
  20%
• Product Price = $125 + Surgery
  ($400)
• Net Present Value = $123,051,509
• Internal Rate of Return = 87.13%
Project Schedule
Deliverables
By the end of the semester:
• A specific actuation technique of
  soft lithography will have been
  chosen
• A specific health condition that the
  device will be applied to
• A schematic of the final product to
  allow for fabrication in the second
  semester of a macro-scaled device
• Prototype Investigation
Conclusions
• Pro/Engineering Problems
• Plans for Next Semester
 – Concentration of Medication in
   Solution
 – Finalized Prototype Design
Questions
Fluid Mechanics
Calculations
Fluid Mechanics
Calculations
Fluid Mechanics
Calculations

								
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