RESEARCH ON MEASUREMENT METHOD FOR INTERNAL DEFORMATION OF POROUS HYDROGEL SCAFFOLDS

As a temporary extracellular matrix in tissue engineering, porous hydrogel scaffolds not only provide spatial support for the survival of seeded cells but also redistribute external mechanical stimuli through their own structures, thereby constructing a mechanical microenvironment that can regulate the physiological activities of cells. However, how to quantitatively characterize and regulate the mechanical microenvironment within tissue engineering porous hydrogel scaffolds is the key to achieving in situ tissue regeneration. In this paper, aiming at the "semi-continuous" problem in the internal deformation measurement of porous hydrogel scaffolds, a semi-continuous optical coherence elastography (SC-OCE) deformation measurement method is proposed. This method includes a material component identification algorithm, an improved semi-continuous digital volume correlation (SC-DVC) method, and semi-continuous structural strain calculation, which solves the shape function under-matching error caused by the discontinuous deformation of cross-interface sub-blocks and the problem of discontinuity of the strain fitting window across interfaces in the measurement of the semi-continuous structure of porous hydrogel scaffolds. The simulation experiment results based on the backward mapping method show that the mean absolute error of displacement measurement by the SC-OCE method is less than 0.0025 voxels, and the mean absolute error of strain measurement is less than 0.0008, proving that this method has a high theoretical accuracy. Based on the SC-OCE deformation measurement method, the deformation field of the porous silk fibroin and type II collagen tissue engineering scaffold was quantitatively characterized. The experiment found that the discontinuous structure exhibited a nonlinear and non-uniform strain field. The mechanical microenvironment constructed by porous hydrogel scaffolds plays an irreplaceable role in in situ tissue regeneration. The SC-OCE method can provide a quantitative basis for the regulation of the mechanical microenvironment and further guide the in situ regeneration of tissue engineering.