Transient electronics are an emerging technology. They can dissolve, disintegrate, or otherwise physically disappear in a controlled manner. Possible applications include resorbable/degradable biomedical implants. 2D materials are of interest due to their unique mechanical, thermal, electrical, and optical properties.

Kyung-Mi Lee, Korea University College of Medicine, Seoul, John A. Rogers, Northwestern University, Evanston, IL, USA, and University of Illinois at Urbana-Champaign, USA, Jong-Hyun Ahn, Yonsei University, Seoul, Republic of Korea, and colleagues have studied the bioabsorption and biocompatibility of monolayer molybdenum sulfide in biofluids and tissues of live animal models.

The team used monolayer MoS₂ grown by chemical vapor deposition (CVD) and measured its lifetime in phosphate-buffered saline solutions at different temperatures and pH values. The material completely dissolves in about two months. The lifetime can be controlled by tuning the material’s grain size and the number of defects in its structure. The researchers also determined the cytotoxicity of MoS₂ in the form of continuous films, nano-sized flakes, and in the dissolved state. In cell cultures and mice no cytotoxicity or tissue damage was found.

To demonstrate the potential of the material, the team developed implantable, degradable sensors based on MoS₂ that can measure pressure and temperature. This might be useful to monitor patients after a traumatic brain injury. The sensors were tested in mice. They gave very similar results compared to a commercially available non-degradable sensor device. According to the researchers, the results show the potential of 2D materials for biologically and environmentally resorbable technologies.

• CVD-grown monolayer MoS₂ in bioabsorbable electronics and biosensors,
  Xiang Chen, Yong Ju Park, Minpyo Kang, Seung-Kyun Kang, Jahyun Koo, Sachin M. Shinde, Jiho Shin, Seunghyun Jeon, Gayoung Park, Ying Yan, Matthew R. MacEwan, Wilson Z. Ray, Kyung-Mi Lee, John A Rogers, Jong-Hyun Ahn,
  Nat. Commun. 2018.
  https://doi.org/10.1038/s41467-018-03956-9