Hector Carmona

ERC for Revolutionizing Metallic Biomaterials ‐
Biodegradability & Microfluidics Test Bed
Leon White (PhD ‐ NC A&T)
Hector Carmona (REU – Cal State LA)
November 16, 2012

TEAM
Leon White: PhD Student – North Carolina A&T State University
• Macro level corrosion testing of Mg alloys
• Development of Coatings for Mg alloys
Hector Carmona: REU – California State University, Los Angeles
• Microfluidic chip fabrication
• Micro-level corrosion study
Aditya Abadve: High School Student – Greensboro Day School
• Corrosion of Mg alloy in Simulated Body Fluid
• Hydrogen Evolution Tests
Aebeyo Abraha: RET- Smith High School Greensboro, NC
• Studied how different aqueous solutions affect the corrosion of Mg alloys

Center Vision
“Revolutionizing Metallic Biomaterials”
Research Innovation (Technology/ Devices)
The Vision is to Revolutionizing Metallic Biomaterials and underlying
sciences and technologies leading to engineered systems that will interface
with the human body to prolong and improve quality of life
Coupled with the development of a vibrant, diverse workforce wellprepared
for the multidisciplinary and global challenges and opportunities
of the new millennium.
Workforce of Tomorrow (Educating Next Generation)

NSF-ERC for Revolutionizing Metallic Biomaterials
National Priority to become the Global Leader
Craniofacial and Orthopedic Applications
Cardiovascular Devices
Responsive Biosensors
“Imagine Implants with their own intelligence that
adapt to biological changes of the patient and are
automatically eliminated from the body after healing”
TRAUMA Medical spending: Close to $250 billion
mini plate surgeries led to infection . Ti plate fixations need to be
removed due to complications, infections, pain
stents are difficult to remove and additional stents must be
inserted (elicit an immune response that can lead to the growth of
scar tissue and the formation of blood clots)
Value of regenerative implants, Degradable metal anchors,
screws, plates, stents and drug eluting stents, staples,
sutures, sternal wires, and meshes
PRICELESS
Cleft Lip
Malformations
Complex fractures of the Tibia
and Femur: Need for Resorbable
Fixation Plates, Pins and Screws
Before After

Bone
Fracture
The Teams’ Dream
Screws, pins,
plates and etc

Corrosion – Complex Interplay
“Corrosion is deterioration of metal and is caused by the
metal’s reaction with environment.” (Joe H. Payer).
3. 주요 설문 내용
1. Metal
Metal’s Properties
(Electrode’s Potential)
3. Interface dynamics
Electrochemical reaction kinetics
2. Environment
Complex In Vivo Environment

Biodegradability Test Bed
MACRO Scale MICRO Scale
Various Mg Alloys Used
Microfluidics Channels

Optical Images (10 day Immersion test)
Same Alloy, Different Immersion Solution

MicroCT Images: Corrosion
Corrosion propagation
Hydrogen evolution, stress generation, and crack propagation
Corrosion product formation in pitting area

Microfluidics Approach
• Must understand the microenvironment and role of grain
boundaries and alloy elements in corrosion.
• Behavior and precise control and manipulation of fluids
that are geometrically constrained in micro‐channels.
• Develop a 4 channel magnesium gradient into different
cell culture chambers and observe their behavior.
• This allows us to test 4 different magnesium
concentrations using only nano‐liters of fluid and cell
cultures.

Dynamic cell culture
Microfluidics
• Develop novel micro-devices which can study cell/tissue
behavior on corroding Mg surface
• This device can provide spatiotemporal behavior of
cell/tissue under the corrosion controlled parameters
including surface area, volume of media, surface to
volume ratio, pH change, osmolality, Mg ion concentration,
hydrogen gas evolution, surface passivation.

Inlet
Syringe pump
Velocity
Profile(cm/s)
Q=500e-6L/min
Microfluidic chip
Outlet
COMSOL simulation
Microfluidics Approach
Mg
Cross-section
Mg alloy
PDMS-PDMS bonding
- Microfluidic chips are successfully fabricated
- Platelet solution flow
- More severe corrosion in flow environment
- Less platelet adhesion on toxol-coated surface
AZ31B AZ31B
Static Incubation (1hr) (1hr, 50 µL/min)
- Platelet adhesion test using platelet-rich plasma
- Sodium Citrate (3.2 %)

Coating Development –A Possible Answer
Immersion Test

6.35mm
2mm
In Vivo Testing

Strategic Plan of the ERC‐RMB

•16‐year teaching experience at Smith High School
•Selected for US Dept of State Teachers for Global
Curricula (TGC) Program
•Only 65 teachers selected for 2012 TGC program
•Visited India in July 2012 as State Dept Scholar
Aebeyo & Aditya
•Young Scholars Participant 2011 & 2012
•Selected for Center for Creative Leadership
Program
•Applying for top Universities in Biomedical
Engineering

THANK YOU