BME 4301 Final Exam Questions with 100% Correct Answers
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Course
BME
Institution
BME
Define the working principle, probe depth (surface sensitivity) and information
provided by AFM and optical profilometry - ANSWER AFM - measure surface
roughness (tip moves across surface, movement tracked by laser, info captured by
computer), micron level probe depth, requires contact
Optical ...
BME 4301 Final Exam Questions
with 100% Correct Answers
Define the working principle, probe depth (surface sensitivity) and information
provided by AFM and optical profilometry - ANSWER AFM - measure surface
roughness (tip moves across surface, movement tracked by laser, info captured by
computer), micron level probe depth, requires contact
Optical Profilometry - high precision, optical method to measure surface topography,
roughness and height, non-contact, non-destructive, capable of nm level resolution
across large fields of view - measure interference between reference and sample light
beams (recombining = travel different distances)
***SEE FIGURES
Differentiate between the concepts of bioinertness and bioactivity with regard to a
surface coating - ANSWER - Bioinert: optimize surface properties, minimize toxicity
(change surface roughness to reduce slip)
- Bioactive: more biologically based approach to cause specific
response (hydroxyapatite on orthopedic implants)
List and describe the characteristics that are unique to the surface of a biomaterial -
ANSWER - Surface Topography
o AFM
o Profilometry
- Microstructure
o Stereomicroscope
o Light microscope
o Polarized, fluorescent, interference contrast microscope
,o Scanning electron microscope
- Composition
o EDX
o ESCA/XPS
o TOF-SIMS
o IR microscopy
- Surface Energetics
o Contact angle
Scanning Electron Microscopy (SEM) - ANSWER - 2D image with 3D visual perspective
- 20x to 30,000x
- surface morphology, chemical composition
- electrons produced at top column, accelerated down through lenses/apertures to
produce focused beam, scans surface of sample (IN VACUUM)
- requires sample prep (dry and conductive - sputter coating)
- peaks brighter, pits darker
- Depth: 0 - 400Å
IR Spectroscopy (FTIR) - ANSWER - Probe in/out: infrared radiation
- Info: structures and types of covalent bonding, functional groups
- Principle: IR radiation is adsorbed and excites molecular vibrations
- Depth: 10-15 microns
EDX/EDS - ANSWER - Probe in: electrons
- Signal out: characteristic X-rays
- Info: elemental analysis or chemical characterization
- Depth greater than 1 micron
- ***added to SEM
X-ray Photoelectron Spectroscopy (XPS or ESCA) - ANSWER - Probe in: X-ray
- Signal Out: photoelectrons
,- Info: elemental composition and chemical bonding
- Principle: photoelectric effect
- Depth: 100Å
Secondary Ion Mass Spectroscopy (SIMS) - ANSWER - Probe in: ions
- Signal out: secondary ions
- Info: elemental and molecular composition
- Principle: release of secondary ions, mass spec
- Depth: 10Å
What is the difference between the terms "adsorption" and "absorption"? - ANSWER -
Adsorption: accumulation and adhesion of molecules or larger particles to a surface
without surface penetration
- Absorption: taking up of a solvent and molecules by a material, penetrates material
surface
How is water as a solvent involved during protein adsorption to a biomaterial? -
ANSWER Very polar/covalent, hydrogen bonding in water direct interaction with
surfaces (loves other charged species)
- Hydrophobic/hydrocarbon surface: water tries to minimize interaction with surface
- Hydrophilic surface
Globular protein shaped by environment
Provide two examples of surface dynamics - ANSWER - Changing geometry
- Dynamic rearrangement
- Adsorption to surface
Describe what is meant by "excess surface free energy" - ANSWER Atoms at
surface have some unbound components - can react more readily
, Is protein adsorption energetically favorable? Why or why not. - ANSWER Non-specific
protein adsorption reduces free energy = energetically favorable
Why is non-specific protein adsorption an important topic in the study of biomaterials? -
ANSWER Protein adsorption creates a new surface that triggers the foreign body
response and initiates blood clotting --- important to consider in biomaterial design and
application
Understand the fundamental nomenclature of polymeric structure. - ANSWER "poly" =
many, "mero"= parts
'mer' - repeating unit
Synonym = macromolecules
*** Shorthand Form
homopolymers
copolymers
With a random coil model sketch, compare and contrast the structures of an amorphous
thermoplastic to a semi-crystalline thermoplastic to a thermoset. - ANSWER Amorphous
thermoplastic: overlap
Semicrystalline thermoplastic: greater areas of adjacent interaction between chains
* Thermoplastics used most as biomaterials
Thermoset: covalent cross-links between chains, "cured" (forms cross-links), adhesives
* Used as load-bearing adhesives or precision joining of electronics
** SEE FIGURES
Areas of crystallinity = Areas of stronger chain interaction
Semicrystalline = harder because of more tight interactions(?)
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