Posted by Debbi Cohen on Wed, Jul 21, 2010 @ 03:20 PM
ASTM F2256 describes in detail how to prepare and test tissue adhesives. This standard describes the methods used to compare and characterize different types of adhesives and for manufacturing quality control of the tissue adhesive based medical devices.
Medical professionals are now using tissue adhesives in place of, or in addition to, the standard sutures or staples to close wounds, surgical openings, and other bandage or wound applications. Defining the adhesive strength of these products determines where, how, and when the adhesive can be used in a medical procedure.
Sample preparation for test substrates; frozen or split bovine, porcine, or ovine tissue freshly harvested from the target organ of a domestic animal. Sample preparation guidelines discussed in detail in section 6, 7, and 8. ASTM F2256
Test Procedure
- Sample specimen width 2.5 +-0.1 cm
- Sample specimen length 15 +-0.2cm (2.5 unbonded, 12.5cm bonded)
- 10 specimens - individual tests and results accumulate with a statistical summary. In some cases, more samples may be needed to obtain a more accurate measure of mean strength.
- Condition specimens for 1 hour +-15 min.A)Tissue Adhesive -internal use-37 degrees Celcius in phosphate buffered saline. B)Tissue Adhesive- external use-30 degrees Celcius and 50%+-5% relative humidity. C)For quality control- 23 degrees celcius and 50%+-5% relative humidity.
- Secure the specimen according to the diagram above.
- Pull sample at a constant rate of 250mm/minute until break.
- Plot load vs. displacement and record observation on reason for bond area failure. (ie; adhesive, substrate)
- The specification asks the user to set up the testing profile in a particular way. Using an ADMET Testing System and MTESTQuattro PC based servo control data acquisition, analysis, and reporting software the following profile can be established.
- Specimen geometry- bonded length 12.5cm.
- Specimen ID with auto increment for data file and results file names.
- Grip separation- 2.5cm
- Logging threshold set to 2.5cm displacement.
- Calculate Average Load between extension points- 2.5cm and 22.5cm
- Calculate T-Peel strength- Divide average load (n) by width of specimen (cm)
- Show statistical summary report(high, low, mean, st. dev, range,+-3 sigma) This report is found in a results file compiled of all specimens tested with this profile and meeting the substrate description defined earlier in sample preparation section.
For reference to ASTM D1876 blog post and testing video.
Recommended equipment
Single Column Universal Testing System or Dual Column Universal Testing System equipped with MTESTQuattro, load cell, vise grips and inserts.
Optional Bath fixture available from ADMET in many sizes for Tissue Samples that must remain in solution throughout the testing. Grips are specially coated to maintain integrity in solution.
Contact ADMET 1-800-667-3220 or info@ADMET.com for more information.
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