Applied Biomaterials

At Southwest Research Institute (SwRI), multidisciplinary teams of scientists and engineers work with industry and government to develop and bring to the market advanced biomaterials and implants for demanding medical applications. For more than 30 years, SwRI has been recognized internationally as a leader in biomaterials, materials science, computational engineering/mechanics, and biomechanics. The Institute applies advanced engineering and computational capabilities and unique laboratories to solve specific material- and mechanics-related problems.

Expertise includes:

• Materials development and qualification
  
  
• Materials characterization
  
  
• Device failure analysis
  
  
• Component design and analysis
  
  
• Biomechanics and micromechanics
  
  
• Tissue engineering
  
  
• Customized materials and component testing

SwRI's state-of-the-art facilities offer integrated solutions to biomaterials-related problems. Facilities include:

• Materials processing and synthesis laboratories
  
  
• Materials testing equipment
  
  
• Microscopy and characterization laboratories
  
  
• Advanced computational systems
  
  
• Specialized mechanics and micromechanics test facilities
  
  
• Surface modification facilities

Materials Development & Qualification

To address critical biomaterials issues for the medical device, implant, and tissue engineering communities, SwRI engineers and scientists modify and develop ceramics, polymers, metals, and composites with tailored properties. Using state-of-the-art laboratory equipment, specialists in materials processing work closely with testing and characterization experts to rapidly develop new materials for a variety of implant and device applications. SwRI materials development capabilities include:

• Monomer and polymer synthesis
  
  
• Ceramic and glass processing
  
  
• Composite design and fabrication
  
  
• Ion implantation, plasma source ion implantation, and ion beam-assisted deposition (IBAD)

Specialty materials processing facilities, such as this furnace used to process glass and glass ceramics, allow SwRI engineers to formulate, process, and improve bioceramics and other biomaterials.

Institute programs have developed or synthesized:

• Biocompatible coatings for reduced friction and increased wear resistance (e.g., diamond-like carbon)
  
  
• Biocidal and antithrombogenic coatings
  
  
• Ultrahigh molecular weight polyethylene
  
  
• Specialized biopolymers (e.g., protein and dental)
  
  
• Ceramic, polymeric, and metallic composites
  
  
• Implantable controlled release materials
  
  
• Molecularly imprinted polymers
  
  
• Specialized silicone polymers

SwRI capabilities include:

• Ceramic powder processing (e.g., Al2O3)
  
  
• Bioactive glasses and glass-ceramic processing (e.g., HA, AW)

SwRI evaluates biomaterials, providing:

• Standardized testing for new suppliers
  
  
• New materials qualification
  
  
• Mechanical, abrasion, and wear testing
  
  
• Regulatory approval consulting
  
  
• Standards and regulation compliance, including FDA-QSR, ANSI, IEC, FCC, CISPR, and ASTM

Materials Characterization & Device Failure Analysis

SwRI has extensive experience characterizing implants and explants under Good Laboratory Practice guidelines. Independent device-failure analyses are routinely performed.

Biomaterials evaluated include:

• Al₂O₃, ZrO₂, and quartz
  
  
• Bioactive glass-ceramics
  
  
• Biocompatible polymers and metals
  
  
• Dental composites
  
  
• Bone, dentin, and soft tissues

The Institute is particularly adept at implementing novel approaches in:

• Mechanical and micromechanical testing
  
  
• Microstructural characterization
  
  
• Chemical analysis
  
  
• Coatings characterization
  
  
• Explant and failure analysis
  
  
• Special test development and validation

SwRI scientists obtained the first atomic force microscope images of in vivo-generated submicrometer polyethylene wear debris, which is considered a major cause of artificial hip implant failure.

SwRI's facilities complement those of more product-focused biomedical companies. Institute capabilities include:

Testing

• Multiaxial mechanical testing
  
  
• Controlled-environment fatigue testing
  
  
• Experimental and analytical fracture mechanics

Microscopy

• Optical
  
  
• Scanning and transmission electron
  
  
• Atomic force

Chemical analysis

• X-ray diffraction
  
  
• Gel permeation chromatography
  
  
• Scanning Auger, energy dispersive, Raman, and Fourier transform infrared spectroscopy
  
  
• Particle size analysis

Customized Materials & Component Testing

New biomaterials and medical devices must be evaluated under intended service conditions to determine their performance. To meet client requirements, SwRI applies its extensive design, instrumentation, and mechanical test experience to develop unique and/or customized test devices. To test biomaterials, biological materials, and implants, engineers have developed special equipment and protocols.

SwRI designs, assembles, and qualifies specialized measurement tools, such as this customized strain gage, which measures both normal and shear forces simultaneously.

Using an Institute-designed miniature compact tension test, engineers measure the fracture toughness of a novel dental composite material. Intact and failed specimens of dental composite material are shown in the on the right.

Specific examples include:

• Custom friction and wear test machines
  
  
• Special strain gages
  
  
• Heart valve quality assurance test equipment
  
  
• Implant abrasion and fatigue machines
  
  
• Advanced sensors
  
  
• Special biological material multiaxial test methods
  
  
• SEM loading stages for micromechanical characterization
  
  
• Brachytherapy device testing
  
  
• In vitro bench testing of medical devices and components
  
  
• Biocompatibility and hemocompatibility testing
  
  
• Electromagnetic compatibility and interference testing

Component Design & Analysis

SwRI engineers and scientists use a broad range of computational and analytical tools to assess the actual versus desired functional performance of new biomaterials and devices in both current and new applications. These iterative design and analysis methods provide faster, more cost-effective product designs and refinements.

SwRI design and analysis expertise includes:

• 3-D parametric computer-aided-design modeling
  
  
• Advanced finite element analysis
  
  
• Probabilistic mechanics and reliability analysis
  
  
• Reliability-based design optimization

Integrating these capabilities while working closely with client technical experts, SwRI engineers can efficiently evaluate the impact of design changes on device function and performance.

Experienced SwRI engineers use Institute-developed or commercially available software tools to:

• Evaluate component reliability
  
  
• Optimize device design
  
  
• Reduce reliability testing requirements

Specific applications for these probabilistic tools include:

• Probabilistic orthopedic implant design
  
  
• Cervical spine risk-of-injury analysis

Biomechanics & Micromechanics

The mechanical interaction of an implant or device with surrounding hard and soft tissue often determines its long-term success in the body. Institute staff members characterize the structural and micromechanical behavior of biological materials and biomaterials, providing clients with critical information that enables them to improve the design and efficiency of their devices. Understanding the mechanical environment of bone and cartilage cells enables engineers to optimize the design of tissue-engineering scaffold materials used to repair and regenerate musculoskeletal tissues.

Advanced in situ microscopy testing devices allow biomaterials and biological materials to be observed at high magnification with the atomic force microscope while being subjected to controlled levels of stress or deformation.

Using an atomic force microscope, SwRI staff members image cortical bone at ultrahigh magnification. With an understanding of how microstructural damage occurs in bone, scientists may gain insight into advanced treatments for bone diseases such as osteoporosis.

Using SwRI's multidisciplinary capabilities, Institute engineers provide a wide range of services, including:

• Whole-bone structural property evaluations
  
  
• Biological and biomaterial micromechanical  testing and analyses
  
  
• Micromechanical strain and displacement measurements
  
  
• Tissue scaffold micromechanical evaluations

Laboratory facilities include sophisticated instrumentation such as:

• In situ microscopy mechanical testing devices
  
  
• Atomic force microscopy (AFM)
  
  
• AFM in situ loading stage

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