Superwettable Microchips as a Platform toward Microgravity Biosensing.

The construction of the Space Station provides a spaceflight laboratory, which enables us to accomplish tremendous short- and long-duration research such as astronomy, physics, material sciences, and life sciences in a microgravity environment. Continuous innovation and development of spaceflight laboratory prompted us to develop a facile detection approach to meet stringent requirements in a microgravity environment that traditional experimental approaches cannot reach. Here we introduce superhydrophilic microwells onto superhydrophobic substrates that are capable of capturing and transferring microdroplets, demonstrating a proof-of-concept study of a biosensing platform toward microgravity application. The capability of manipulating microdroplets originates from the capillary force of the nanoscale dendritic coating in superhydrophilic microwells. Based on theoretical modeling, capillary forces of the superhydrophilic microwells can dominate the behavior of microdroplets against the gravity. Direct naked-eye observation monitoring of daily physiological markers, such as glucose, calcium, and protein can be achieved by colorimetric tests without the requirement of heavy optical or electrical equipment, which greatly reduced the weight, and will bring a promising clue for biodetection in microgravity environments.