Ultrasound elastography of fibrous non-woven PGA scaffold in compression

A. W T Shum, Yongping Zheng, A. F T Mak

Research output: Chapter in book / Conference proceedingConference article published in proceeding or bookAcademic researchpeer-review

Abstract

The biomechanical properties of the fibrous non-woven poly(glycolic acid) (PGA) scaffolds were studied before and after 14 days of in vitro degradation using ultrasonic measurement. The sample scaffolds were tested in phosphate buffer saline (PBS, pH 7.4) for 10% compression followed by a period of force relaxation. An ultrasound beam of 2kHz was transmitted into the fibrous scaffold, and the reflected ultrasound echoes were captured to calculate the non-uniform deformation field. Force was measured by a low profile compressive load cell connected in series to the specimen and the ultrasound transducer. The initial modulus, equilibrium modulus and equilibrium depth-dependent strains were then evaluated by selecting the dominant ultrasound signals at different depths within the PGA scaffold, where the displacement of each different layer was derived using a cross-correlation echo tracking method. Results showed that the initial modulus was higher than the equilibrium modulus for both scaffold samples. At equilibrium, the moduli determined at 0 day and 14 days degradation were quite similar, being 14.2kPa and 12.6kPa respectively (Table 1). The depth-dependent deformation field was also noted in the fibrous nonwoven scaffolds (Figure 1 and 2), while the evenly distributed deformation by averaging the strain from different layer was shown in Figure 3 and 4. From the equilibrium depth-dependent deformation, it was observed that the fibrous scaffolds before and after 14 days of degradation were quite soft near the surfaces and suffer in the middle zone. Results showed that both the initial moduli measured by ultrasound-compression method in PBS at 0 day and 14 days of in vitro degradation were about four times stiffer than the results obtained in air using conventional mechanical testing (Table 1). The results revealed that the compressive biomechanical properties of the fibrous nonwoven PGA scaffolds were highly depth-dependent. It is suggested that ultrasound elastography appears to be a valuable tools for biomechanical properties measurements.
Original languageEnglish
Title of host publicationTransactions - 7th World Biomaterials Congress
Pages1223
Number of pages1
Publication statusPublished - 1 Dec 2004
EventTransactions - 7th World Biomaterials Congress - Sydney, Australia
Duration: 17 May 200421 May 2004

Conference

ConferenceTransactions - 7th World Biomaterials Congress
CountryAustralia
CitySydney
Period17/05/0421/05/04

ASJC Scopus subject areas

  • Engineering(all)

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