Figure 1.

(A) Chemical structure of sodium alginate and photos of un-cross-linked sodium alginate, cross-linked alginate with Ca²⁺, and Ca²⁺ cross-linked alginate with fat addition. (B) CT images of material variations: 2 wt % alginate cross-linked with 0.2 wt % CaCO₃ and with different coconut fat additions (0, 20, and 30 wt %). The window level and window width are set at 40 and 350, respectively. The increase in fat concentration leads to a lower contrast, i.e., lower CT attenuation. The numbers in front of the ingredients in the figures represent weight percentages (e.g., 2Alg/0.2Ca/10Fat represents 2 wt % alginate/0.2 wt % CaCO₃/10 wt % fat). (C) US images of material variations: 2 wt % alginate with different cross-linking degrees (0.2, 0.4, and 0.6 wt %) prepared in layers. The difference in shear wave velocity can be seen by the lower contrast of the less cross-linked middle layer in relation to the higher cross-linked upper and lower layers. (D) Filtered Raman images of material variation: 2 wt % alginate cross-linked with 0.2 wt % CaCO₃ and with different coconut fat additions (10, 20, and 30 wt %). The fat signal appears bright yellow with respect to the bending CH₂ vibration at 1445 cm^–1. (E) Demonstration of how the Hounsfield unit and elastic modulus of the hydrogel composites developed in this study can be adjusted independently to achieve the required values of human tissue and organs. The Hounsfield unit and elastic modulus of human tissue and organs were obtained from the previous studies.¹⁸⁻²⁴