6.3 Biomimetic Skin

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Figure 6.14: Approaches for self-healing structural materials (adapted from [39]).

the healing process needs to operate at physiological conditions, i. e., 37 °C and a neutral

pH. An example of such a system is zwitterionic hydrogels [43] (Figure 6.15). Basically,

the healing process is based on charge attraction; charged polymers are flexible and

have a large driving force to recombine with the opposite charge. Therefore, healing

is automatic and fast. It is important, though, to create a material that is stable at a

temperature above body temperature.

So far, the important properties of skin, its function as a platform for sensors, its re-

sponsiveness to the environment, and its self-healing abilities, have been investigated

separately. But is there a material that is as complex in its structure and functions as

skin that can do all of this at the same time, as skin can? The short answer is: not yet.

There are a lot of examples of biocompatible hydrogels in the tissue engineering litera-

ture (e. g., [44] and references therein) that encourage the redevelopment of the tissue

structure. Water and chemical transport in hydrogels [45–47] and the exact mechanical

properties [48] have been investigated as well. However, these are just platforms that the

other properties (sensing and responsiveness to the environment) can be built upon. In

addition, as materials go, scaffold hydrogels are not yet self-healing.