High-Sensitivity Fully Printed Flexible BaTiO₃-Based Capacitive Humidity Sensor for In-space Manufacturing by Electrohydrodynamic Inkjet Printing

Long-duration exploration missions require a paradigm shift in the design and manufacturing of space architectures. Humidity is a basic but crucial parameter of the environment and human health that needs to be monitored. Flexible sensors are considered consumable and current manufacturing techniques are not applicable due to limits of the technology in a space environment, the operation cost, and the allowable space. In this paper, we demonstrated a case study of “In Space Production Applications (InSPA)”. Electrohydrodynamic (EHD) inkjet printing technology is capable of manufacturing circuits in micro-gravity due to its unique mechanism, to fabricate a high-sensitivity flexible humidity sensor. The sensor shows very competitive sensitivity and response time compared to other previous work. The wireless human respiratory monitoring circuits were built based on the sensor and showed good accuracy and sensitivity to monitor the respiratory rate and amplitude for humans.