A Capacitive Pressure Sensor Seamlessly Embedded in the Microchannel

Monitoring the fluid pressure within microchannels is crucial for the research of microfluidics and the development of microfluidic devices. Existing pressure sensors embedded within silicon microchannels commonly require drilling holes on the wall surface to install tap lines, which not only alters the microchannel structure but also makes the measurement susceptible to interference from factors such as residual bubbles. In addition, existing methods may also have drawbacks such as poor stability, complex testing systems, assembly difficulties, and low processing reliability. This article presents a capacitive pressure sensor that can be seamlessly embedded in silicon microchannels for monitoring dynamic pressure. The sensor has minimal impact on microchannel morphology, making it suitable for pressure measurement in microchannels of various shapes. The manufacturing of the sensor based on micro-electromechanical systems (MEMS) technology is simplified by the application of adhesive bonding. The sensor can monitor microchannel dynamic pressure within 0-120 kPa. The response and recovery times of 68 and 79 ms, respectively, highlight the sensor's excellent dynamic capabilities. Moreover, its stable response over 500 pressure square wave cycles, coupled with the consistency of the response calibration on day 1 and day 63, affirms the sensor's exceptional stability. Its successful application for the measurement of liquid pressure at various locations within microchannels further attests to its efficacy. These attributes underscore the significant potential of the sensor in the study of the microscale flow.