Polydimethylsiloxane (PDMS) is widely used in microfluidics and medical devices; however, its inherent hydrophobicity limits its applications. This can be resolved by the formation of polyethylene glycol (PEG)-based hydrophilic coatings. Here, we aimed to prove that PDMS surfaces modified with low molecular weight PEG (400) provided a more stable hydrophilic surface. The lowest contact angle achieved via using PEG400 and the “grafting from” approach was 8.6 ± 3.5°. Under perfusion conditions, imitating arterial and capillary flows, such coatings were considerably stable, and the contact angle was kept at 45.5° after 3 days. Moreover, the applied surface modifications preserved surface roughness, elastic modulus, and optical transparency. Thus, these findings confirmed that the “grafting from” approach with low molecular weight PEG could be the most effective strategy to form hydrophilic PDMS coatings with optimal performance in biomedical applications.

One of the common issues in the R&D of new drugs is the failure of clinical trials caused by the species-specific inadequacy of animal models to assess drugs’ efficiency and safety. Therefore, systems like organ-on-a-chip and, particularly, liver-on-a-chip (LOC) can be an efficient tool for recapitulating in vivo-like human physiology at the microscale. This review focuses on discussing LOC design, emphasizing its architecture and validation to reveal the trends in searching for a balance between biomimetics and functionality. We found that the huge variety of already published models can be divided into five groups based on their configuration complexity: flat one-channel, flat two-channel, vertically stacked multilayered, hexagonal-patterned, and multi-well chips. While researchers attempt to recapitulate the liver’s histology and its functions in detail by increasing the complexity of devices’ architectonics, industrial companies prefer to promote more simple and flexible solutions. Thus, the LOC designs of the future require neglecting some liver characteristics to make them standardizable and sustainable, which could facilitate their introduction into the market and clinics.