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MECH 500: Bionic Implants and Devices

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MECH 500: Bionic Implants and Devices Sumitra Rajagopalan sumitra.rajagopalan_at_polymtl.ca Office Hours: 5pm 5:30 pm Mondays 4 pm- 5pm Fridays Bionic Implants ... – PowerPoint PPT presentation

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Title: MECH 500: Bionic Implants and Devices


1
MECH 500Bionic Implants and Devices
  • Sumitra Rajagopalan
  • sumitra.rajagopalan_at_polymtl.ca
  • Office Hours
  • 5pm 530 pm Mondays
  • 4 pm- 5pm Fridays

2
Bionic Implants Devices Overview
  • Layout of Course
  • Evaluation Expectations
  • What is the course really about?
  • Course Prologue

3
Course Layout
  • Basic Notions in Medical Devices
  • Functional Biomaterials for Bionic Implants
  • Design of Soft-Tissue vs. Hard Tissue Implants
  • Implant Surfaces and Interfaces
  • Bioactive and Bioresponsive Implants
  • Functional Tissue Engineering and Bioartificial
    Organs
  • Bioelectrodes, Artificial Muscles and
    Neuroprosthetics
  • Brain-Machine Interface and Cortical Prosthetics
  • Implantable Devices for Minimally-Invasive
    Surgery
  • Biosensors, Bioelectronics, Closed-Loop
    Management

4
Course Evaluation
  • Class Participation 15
  • Critical Review of Article(s) OR Case Study 1
    20 (Assigned)
  • Third week of September, due early November
  • Case Study 2 25 (Assigned or Chosen)
  • Third week of October, due at the end of semester
  • Take-Home Exam (5 questions) 40
  • December 1st, due December 10th

5
What you will get out of the course
  • A broad, comprehensive overview of the field
  • Study the human body from a materials/mechanical
    engineering perspective
  • Understand and appreciate differences between
    living and man-made materials and structures
  • Custom-design materials and structures to suit
    biological function Biomimicry
  • Design appropriate material surface and interface
  • Identify optimal control feedback system for
    implant
  • Understand and appreciate factors governing
    behaviour in-vivo
  • Basic design of biosensors and bioelectronic
    implants including Bio-mems and nems
  • Getting medical device to market
  • Apply knowledge of human factors engineering to
    extreme enviroments outer space

6
So, what is this course really about?
7
Medical Devices A Multidisciplinary Enterprise
biology, physiology, biochemistry, immunology
Life Sciences
BIOMATERIALS BIOIMAGING BIONICS BIOMECHANICS BIO
INSTRUMENTATION
electronics, image processing, mechanics,
chemistry, physics, materials, mathematics
Physical Sciences
Engineering
8
What is a Medical Device?
  • "an instrument, apparatus, implement, machine,
    contrivance, implant, in vitro reagent, or other
    similar or related article, including a component
    part, or accessory which is
  • recognized in the official National Formulary, or
    the United States Pharmacopoeia, or any
    supplement to them,
  • intended for use in the diagnosis of disease or
    other conditions, or in the cure, mitigation,
    treatment, or prevention of disease, in man or
    other animals, or
  • intended to affect the structure or any function
    of the body of man or other animals, and which
    does not achieve any of it's primary intended
    purposes through chemical action within or on the
    body of man or other animals and which is not
    dependent upon being metabolized for the
    achievement of any of its primary intended
    purposes."

www.fda.gov
9
Why Bionic ?
1973
1976
1990
2000
10
Bionics Inspired by Nature
  • Coined by Jack Steeles of the U.S. Air Force in
    1960
  • Studying Nature from an Engineering/ Design
    Perspective
  • Extracting Structural, Design Paradigms.
  • Adopting these paradigms to solve a range of
    engineering problems.
  • Other names Biomimicry,Biomimetics

11
Bionic Implant Device
  • Implant that mimics as far as possible the
    structure AND function of the body part it
    replaces.
  • Interacts with the human body in a bidirectional
    fashion
  • Examples of Bionic Devices Artificial Heart,
    Artificial Muscle, Cochlear Implant,
    Bioelectrodes, Mechanoactive Cartilage
  • Towards seamless integration of implant with
    physiological environment
  • Closed-loop system Example of artificial
    pancreas.

12
Living vs. Man-Made Reflections
13
Living Materials, Structures and Machines
  • Multifunctional Materials
  • Heirarchical, built through self-assembly
  • Ordered, patterned, nano-structured
  • Graded properties and functions throughout
    structure
  • Seamless integration of materials and structures
    of varying properties
  • Control feedback integrated into structure
  • Adaptive
  • 3Rs renewing, repairing, replicating
  • FORM FOLLOWS FUNCTION
  • FORM FITS FUNCTION

14
FORM FITS FUNCTION Reflection
  • Cartilage?
  • Muscle?
  • Bone?
  • Skin?

15
Anatomy of an Implant Design Fabrication
Considerations
  • Biomaterial
  • Bulk Structure
  • Interface
  • Implant Anchoring
  • Sterilisation Method
  • Power Issues in Implant Design
  • Wireless Monitoring of Implant

16
Biomaterials
  • Material intended for implanting in human body

17
Smart Materials Bridging Materials to Life
  • Shape-memory foams
  • Shape-memory alloys
  • Polyelectolyte Hydrogels
  • Piezoelectric Ceramics
  • Electroactive Polymers
  • Self-healing composites
  • Supramolecular Chemistry

18
Bionic Devices Behaviour in-vivo
  • Biocompatibility/Cytotoxicity
  • Ability to function in-vivo with no adverse
    immune reaction
  • Biodegradability
  • Break-down of biomaterial through action of body
    enzymes into non-toxic byproducts.
  • Biostability
  • Resistant to break-down in the human body
  • Biofunctionality
  • Functions as structure intended to replace

19
Inflammation Immune System Host Response
  • Inflammation occurs through foreign body
    response, movement of implant
  • Protein layer formed on implant surface
  • Even "inert" materials cause inflammation
  • Inflammation reaction can adversely affect both
    patient the functioning of implant
  • Engineered biological tissue can cause adverse
    immune reaction
  • Still empirical

20
Solution? Surface Engineering
  • Biorecognisable implant surface
  • Designing templates with cell-adhesion molecules
  • Micro- and nano-texturing of surface
  • Porous Structures Why?
  • Drug-eluting surfaces

21
Functional Tissue Engineering
  • Engineering Living Tissue on Synthetic Scaffolds
  • Scaffolds porous, biodegradable, mimic the
    extracellular matrix
  • Several parameters at play ?
  • Role of Mechanical Engineering Develop
    mathematical models to describe tissue growth on
    scaffolds through these parameters
  • Whats the difference between tissue engineering
    and functional tissue engineering?

Boccafoschi, F et al. Biomaterials 26 (2005)
74107417
22
Interface with Excitable Tissue Toward
Neuromuscular Prosthetics
  • Excitable TissueNerve, Muscle
  • Bioelectronic Devices are either stimulate/record
    biosignals (or both)
  • Electronic Implant consists of
  • Power Source
  • Controller
  • Stimulator
  • Electrode
  • Used in a wide range of pathologies spinal cord
    injuries, parkinsons disease, epilepsy, stroke
    etc.
  • Nerve-electrode interface remains the weakest
    link
  • Study of bioelectric phenomena crucial to
    developing biocompatible electronic implants.

23
Notions in Bioelectricity
  • Equivalent circuits used to model intefacial/
    bioelectric phenomena
  • Impedance Analysis used to calculate parameters
    affecting charge transfer from device-tissue
  • Capacitance
  • Inductance
  • Resistance
  • Models derived used to design medical
    instruments, biosensors and other bionic devices

Zhu, F., Leonard,.E Levin,. N Physiol. Meas. 26
(2005) S133S143
24
Wrap-up Points to Remember
  • Highly multidisciplinary field drawing in on
    chemistry, biology, physiology, mechanics,
    electronics .
  • Unlike the man-made world, Nature SEAMLESSLY
    integrates different components and functions
    into a working unit.
  • Biological materials vastly differ from man-made
    materials and that has to bet aken into account
    when designing implants
  • Bionic Implants emerge ONLY in response to a
    clinical PULL (need)
  • Bionic Implants to be designed with Clinical and
    Market Realities in mind.
  • Role of Mechanical Engineer Interfacing with
    multiple disciplines, interacting with multiple
    professionals.

25
Carbon Nanotube Sheets for use as Artificial
Muscles Discussion Questions
  • Differing requirements for robotic vs. prosthetic
    applications
  • What are the advantages of carbon nanotubes?
  • What are their drawbacks?
  • Predict behaviour in-vivo
  • Follow-up to this work?
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