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
- 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 resultsfile names.
- Grip separation- 2.5cm
- Logging threshold set to 2.5cm displacement.
- Calculate Average Load between extension points- 2.5cmand 22.5cm
- Calculate T-Peel strength- Divide average load (n) by widthof specimen (cm)
- Show statistical summary report(high, low, mean, st. dev,range,+-3 sigma) This report is found in a results filecompiled of all specimens tested with this profile andmeeting the substrate description defined earlier in samplepreparation section.
For reference to ASTM D1876 blog post and testing video.