A Resonant Pressure Microsensor with a Wide Pressure Measurement Range

Abstract

This paper presents a resonant pressure microsensor with a wide range of pressure measurements. The developed microsensor is mainly composed of a silicon-on-insulator (SOI) wafer to form pressure-sensing elements, and a silicon-on-glass (SOG) cap to form vacuum encapsulation. To realize a wide range of pressure measurements, silicon islands were deployed on the device layer of the SOI wafer to enhance equivalent stiffness and structural stability of the pressure-sensitive diaphragm. Moreover, a cylindrical vacuum cavity was deployed on the SOG cap with the purpose to decrease the stresses generated during the silicon-to-glass contact during pressure measurements. The fabrication processes mainly contained photolithography, deep reactive ion etching (DRIE), chemical mechanical planarization (CMP) and anodic bonding. According to the characterization experiments, the quality factors of the resonators were higher than 15,000 with pressure sensitivities of 0.51 Hz/kPa (resonator I), −1.75 Hz/kPa (resonator II) and temperature coefficients of frequency of 1.92 Hz/°C (resonator I), 1.98 Hz/°C (resonator II). Following temperature compensation, the fitting error of the microsensor was within the range of 0.006% FS and the measurement accuracy was as high as 0.017% FS in the pressure range of 200 ~ 7000 kPa and the temperature range of −40 °C to 80 °C.

A resonant high-pressure sensor based on dual cavities

“…In comparison to other resonant high-pressure sensors [16,20,27,28], this developed sensor possessed a wider pressure range, higher correlation coefficients of the pressure sensitivities, higher Q values, and more simple fabrication process (see table 1).…”

“…The intrinsic frequency f 0 of a H-shaped resonator in the first laterally vibrating modal can be approximately calculated by a double ended fixed beam as follows [20]:…”

“…In recent years, in order to compensate for the resonator's frequency variation over temperature, Roshan adopted the ratio of temperature coefficients of two resonators to obtain temperature information [18]. Besides, our previous works in the high pressure sensing areas, such as Lu [19] and Xiang [20], utilized the difference of the temperature sensitivities of the dual resonators to improve the temperature compensation precisions compared to off-chip temperature sensor compensation manners to a great extent in the high pressure sensing areas. Whereas, the linearity and the pressure sensitive range of the sensor were compromised due to difficulties of dual resonators layouts on a limited small-dimension pressure sensitive diaphragm.…”

Research on Integrated 3D Printing of Microfluidic Chips

“…To sum up, there are a variety of microfluidic chip fabrication methods at present that can realize the fabrication of microchannels with complex structures and the packaging of microchannels by bonding in the later stage. However, the manufacturing and packaging of microchannels at present have strict requirements on processing equipment and working conditions, and even pose certain risks [ 34 , 35 ]. Therefore, this paper proposes a microfluidic chip processing method that combines 3D-printing technology and polymer-dissolution technology that can form microchannels inside a PDMS substrate.…”

Effects of Resonator Shape on Nonlinear Resonant Frequencies of a Microresonant Pressure Sensor

“…Zhang et al introduced a micromechanical resonant pressure sensor with two resonators and solved the overload problem [16]. Xiang et al introduced a resonant pressure microsensor in which the silicon islands are deployed on an SOI wafer to improve the equivalent sti ness and structural stability of the pressure-sensitive diaphragm [17]. Zhao et al and Yan et al developed temperature-insensitive silicon resonant pressure sensors with very-low-frequency temperature coe cients [18,19].…”