Transcutaneous plasma stress: from soft-matter models to living tissues

This review critically examines the multiple effects of low-temperature, atmospheric pressure plasma stress on the “on top” (collectively termed cutaneous) materials, to reveal the effects of this stress on the materials that lay underneath, collectively termed sub-cutaneous materials. Plasma generated reactive agents presents stress and trigger relayed effects within the cutaneous layers, leading to transcutaneous penetration of the plasma-induced stress into sub-cutaneous materials. Among the many possibilities from the areas spanning soft matter and life sciences, the effects of reactive plasma agents help improve the outcomes of cutaneous wound healing, reduce skin cancer tumors, and eradicate biofilms on biomedical implant materials. Cutaneous materials include animal skin or laboratory models using soft matter such as liquid media, gels, and cell cultures. Here we examine permeable interfaces of cutaneous materials and sub-cutaneous living tissues subjected to low-temperature atmospheric-pressure plasmas as a multi-modal reactive system producing stress on materials through multiple reactive agents including radicals, excited atoms and molecules, ions, heat, UV, and electric fields. Interaction of plasma-radiative stress with cutaneous materials leads to the unexpected, yet effective transmission of the reactive agents through to sub-cutaneous tissues, potentially systemically through the body. We examine the penetration of plasma-generated stress through the skin or skin models leading to the many interesting effects. In a broader context, this knowledge is relevant to several fields of materials science and engineering from soft matter to biomaterials and may help advance diverse applications ranging from non-thermal processing of soft and flexible materials for flexible electronics and soft robotics to direct skin disease treatment in vivo. Refereed/Peer-reviewed