FIGURE 3.

Various bioink cross‐linking strategies that could be used in bioprinting through portable hand‐held bioprinters. (a) Ionic cross‐linking: A simplified schematic depicting the formation of electrostatic bonds among ions (green) and polymer chains with opposite charges, resulting in a branched network. (b) Enzymatic cross‐linking: A simplified schematic depicting the enzyme‐catalyzed formation of covalent bonds among polymeric biomolecules. (c) Light‐induced cross‐linking: A simplified representation of the cross‐linking process in the presence of a photo initiator (yellow). When exposed to UV light, the photo initiator produces free radicals, which start a polymerization process between the functionalized chains. (d) Thermal energy‐induced cross‐linking: A simplified diagram depicting the structural changes that occur as a result of temperature variations, resulting in the formation of polymer chains