1. Embedded Biomaterial Failure Detection
Client: Raj Ambay, MD, DDS.
Advisor: Willis Tompkins, PhD.
Rexxi Prasasya, Hyungjin Kim, Tu Hoang Anh Mai
Design Requirement
Abstract
Design Requirement
Biomaterials are widely used for medical applications, especially as implantable materials. The wear and tear of these devices cause changes to their intrinsic properties. Currently, there exists no perfect method to detect failure in embedded biomaterials. The goal of our project is to determine a technique that takes advantage of the change in a specific property of the biomaterial as it reaches failure. After conducting mechanical testing for viscoelasticity of the biomaterial, we hypothesized that the materials’ stiffness will change due to failure. In the future we will quantify the correlation between the changes in viscoelasticity and the level of biomaterial failure. Elastography will then be used to detect the changes in stiffness with high sensitivity.
Biomaterial failure determination
Properties changes
Quantification
Non-invasive detection
Clinical utility
Cost: less than $500
Design Proposal
Build phantoms
Conduct strain – time dependent testing
Compare stiffness of intact and failed materials
Quantitatively determine viscoelastic property of failed materials
Conduct viscoelastic testing for specific components
Incorporate viscoelastic properties to elastography
Perform ultrasound-based testing
Determine the minimum sensitivity of elastography
Human testing
Eliminate image dependency
Build a hand-held device
Integrate into clinical setting
Background
Background
Figure 4. Stress and relaxation testing set up
Materials
Metal, polymer, biologically derived, ceramics
Combination of materials
Biocompatible
Applications
Repair
Replacement
Drug delivery system
Limitation
Developing ultrasound transducer with integrated force sensor
Limited access to ultrasound
Highly multidisciplinary project
Unavailable information on basic properties of material
Required long term research
Fig. 1. Degraded artery and valve replacement(Kao, 2008)
Figure 5. Load vs. time graph showing viscoelasticity of biomaterial
Competition
Reference
MRI
Structural changes
Non-metal
Expensive
X-ray
Detect density difference
Low cost
Ambay, R Persomal communication.
“A-Medic 500 Radiographic X-ray Unit.”
Accessed March 06, 2008.
Guerquin-Kern. J.L, et al. “Active microwavetomographic imaging of isolated, perfused animal
organs.” Bioelectromagnetic 1985, p
“How elastography works.” Accessed March 03, 2008.
Itoh, K. et al. “Breast Disease: Clinical Application of US Elastography for Diagnosis.” Radiology 2006; p. 239:341.
Kao, J. “BME 430 lecture notes”
Lakes, R Personal Communication.
Accessed March 03, 2008.
Testing and Result
Stress and relaxation test
Displacement controlled
15% elastic deformation
Variable forces
Structural stiffness: N/m
Materials exhibit viscoelastic properties
Acknowledgement
Prof. Timothy Hall, Prof. Roderic Lakes, Prof. Ray Vanderby, Hirohito Kobayashi, Prof. Tomy Varghese, Susan Lezebnik
Fig. 2. MRI
Fig.3. X-ray