A flexible microfluidic sensor based on main-channel and branch-channels for aerodynamic pressure measurement

Aerodynamic pressure distribution on the surface of aircraft is the main basis for aerodynamic shape design. According to the aerodynamic pressure distribution, the minimum pressure position, the shake wave position and the air separation on the surface of aircraft can be determined, which is of great importance to the aircraft design. In this paper, a flexible microfluidic sensor for aerodynamic pressure measurement is developed. The sensor consists of a flexible substrate with cavities, conductive liquid and electrodes. The cavities in flexible material include two parts, one is the main channel and the other is the branch channel. When external pressure is applied on the sensor, the main channel will be deformed and the conductive liquid in the main channel is forced into the branch channels, which causes the resistance change of the sensor. When external pressure is released, the main channel returns to its initial shape, and the conductive liquid in branch channels will return to main channel due to the capillary force between the conductive liquid and the flexible substrate. The preliminary experimental results demonstrate that the main channel-branch channels design can improve the sensitivity of the sensor up to 2.15 x 10(-2) kPa(-1), and it can also avoid the leakage of conductive liquid. The developed sensor also exhibits fast dynamic response (29 ms), excellent cyclic loading/unloading stability (> 100 cycles). Moreover, experiments are also conducted to investigate the influence of the temperature and humidity. The flexible sensor brings a new opportunity for real-time aerodynamic pressure measurement due to its minor size, high sensitivity, durability and flexibility. (C) 2021 Elsevier B.V. All rights reserved.