High-performance miniature flat pressure sensor for 235°C environment enabled by process optimization

A passive substrate integrated waveguide (SIW) sensor based on the complementary split ring resonator (CSRR) is presented for pressure detection in high-temperature environments. The sensor pressure sensing mechanism is described through circuit analysis and the electromagnetic coupling principle. The pressure sensor is modeled in high frequency structure simulator (HFSS), designed through parameter optimization. According to the optimized parameters, the sensor was customized and fabricated on a high temperature co-fired ceramic (HTCC) substrate using the three-dimensional co-fired technology and screen-printing technology. The pressure sensor was tested in the high-temperature pressure furnace and can work stably in the ambient environment of 25−500 °C and 10−300 kPa. The pressure sensitivity is 139.77 kHz/kPa at 25 °C, and with increasing temperature, the sensitivity increases to 191.97 kHz/kPa at 500 °C. The temperature compensation algorithm is proposed to achieve accurate acquisition of pressure signals in a high-temperature environment.

A miniature all-fiber in-line tip pressure sensor fabricated by 157nm laser pulses is proposed and demonstrated, for the first time to our knowledge. Such a pressure sensor can be operated under high temperature due to its all silica structure. The sensor has been tested for pressure sensing over 0MPa~60MPa, showing a pressure sensitivity of ~83.3pm/MPa, an excellent linearity of 99.998%, and a long-term stability of ±0.03MPa, respectively. Such a miniature fiber-optic pressure sensor could find important applications in automotive and aerospace industries, and down-hole monitoring, etc, due to its extreme compactness, capability for operation at high temperature, easy fabrication, excellent stability, good potential for mass-production.

The passivation step used in the “Bosch” process (alternating etching and deposition steps) to perform deep anisotropic silicon etching has been examined in detail. The effect of pressure, inductively coupled plasma power, temperature, flow rate, and bias power on both deposition rate and film composition has been explored over a relatively wide range. Deposition rate was found to vary significantly as a function of temperature, power, and pressure. In contrast, only two film composition regimes were observed: high fluorine-to-carbon ratio (F:C) films (∼1.6) at low pressure∕high power versus low F:C films (∼1.2) at high pressure∕low power. Optical emission spectroscopy of the deposition plasmas also show only two regimes: C2, C3, and F emission dominated (high F:C films) and CF2 emission dominated (low F:C films). A two-step deposition mechanism is assumed: carbon deposition followed by fluorination. Low F concentration and deposition from large fluorine-deficient CxFy species in the CF2-rich plasmas result in the low F:C ratio films. Films deposited during an actual Bosch cycle generally mirror these bulk films, with slight differences. Analysis of etch:deposition rate ratios as a function of film F:C ratio indicates that, for the conditions studied here, a F:C ratio of 1.45 is optimal for Bosch processing (i.e., has the lowest etch:deposition rate ratio). Further analysis is needed to determine the effect of passivant F:C ratio on feature profiles.

At present, the follow-up platform in the guidance device is mostly the direct drive mode of the motor. in order to reduce the weight and save space The way of wire rope indirect transmission is proposed. In the high-temperature environment, the wire rope will be thermally expanded during the transmission process, resulting in reduced transmission accuracy or even failed due to slippage, and similar problems may occur in the low temperature environment. Since the pre-tensioning device is not easy to set up in a small space, in this paper, the deformation of steel wire rope and transmission wheel in high and low temperature environment is calculated. By calculating the elongation of the steel wire rope in the high and low temperature environment and the thermal expansion of the transmission wheel, the advantages and disadvantages of the automatic tensioning effect of the rope system in high and low temperature environment can be analyzed and compared, which lays a foundation for the improvement of the whole transmission system.

Evanescent-mode-resonator-based and antenna-integrated wireless passive pressure sensors for harsh-environment applications

Langasite microstructure etching and characterization method for high temperature devices

Deep etching of Zerodur glass ceramics in a fluorine-based plasma

The gut microbiome is vital to the physiological and biochemical functions of the host, and changes in the composition of these microbial communities may affect growth and adaptability to the environment. Pomacea canaliculata is an invasive freshwater snail which has become a serious agricultural pest. Temperature adaptation is considered an important reason for the widespread distribution of this species. To date, the contribution of the gut microbes to host fitness of P. canaliculata during long-term temperature stress is not well understood. In this study, the morphological changes and intestinal microbiome of P. canaliculata under long-term stress at low temperature (15°C) and high temperature (35°C) were investigated with laboratory experiments. Compared with control group (25°C), the alpha diversity increased and pathogenic bacteria enriched changed under high and low temperature stress. The effect of high temperature stress on the intestinal microbiome of P. canaliculata was more significant than that of low temperature stress. A sustained high temperature environment led to an increase in the abundance of pathogenic bacteria, such as Aeromonas and Enterobacter, and a decrease in the abundance of immune-related bacteria such as Bacteroidetes, Firmicutes, and Lactococcus. These intestine microbiome changes can increase the risk of diseases like intestinal inflammation, and lead to more deaths at high temperature environments. In addition, with the extension of stress time from 14 to 28 days, the beneficial bacteria such as Bacteroidetes, Firmicutes, and Lactococcus were significantly enriched, while potential pathogenic bacteria such as Pseudomonas, Acinetobacter, Shivalella, and Flavobacterium decreased, suggesting that intestinal microbiota may play an important role in host response to heat stress. These results are consistent with previously reported results that the survival rate of both male and female P. canaliculata no longer significantly reduced after 21 days of high temperature stress, suggesting that the surviving P. canaliculata had gradually adapted to high temperature environments under long-term high temperature stress.

Optical fibre pressure sensors have potential performance advantages over electrical sensors in measuring rapid transients such as shock waves from explosive blasts. We report the development of micromachined optical fibre Fabry–Pérot pressure sensors using a silicon dioxide or nitride diaphragm and detail the fabrication stages of the sensor body and diaphragm. The planar technology used is based on silicon deep etching and direct fusion bonding of silicon wafers. Test results for both types of diaphragm are presented. Sensors with rise times better than 3 µs, range 0.1 to 1 MPa and resolution ∼500 Pa have been demonstrated in explosives trials. Despite the difference in the sign of stress for the two diaphragm types, both demonstrated excellent high-speed response to explosively generated air shocks.

High reliability of piezoresistive pressure sensors by wafer to wafer direct bonding at room temperature

Prolonged exposure to high humidity and high temperature environment can aggravate influenza virus infection through intestinal flora and Nod/RIP2/NF-κB signaling pathway

Recent investigation of single crystal cubic zirconia fiber optic pressure sensor for high temperature environment application is reported in this paper. A fiber optic pressure sensor utilizing single crystal cubic zirconia as a structure material has been designed, developed and tested. The sensor head is a birefringence-based fiber optic sensor in which the will change with the pressure. The pressure response of the sensor has been measured from 0 to 1700Psi. Additional experimental results from room temperature to 1026 /spl deg/C show that cubic zirconia could be used for pressure sensor at high temperatures. Experiment results illustrate the feasibility to apply the designed single crystal cubic zirconia sensor for pressure measurement at high-temperature harsh industrial environments with further development.

A novel all-silica fiber optic Fabry-Perot (FP) pressure sensor with pressure leading-in tube based on microbubble structure is developed and experimentally demonstrated. The FP cavity is formed by fixing the end face of the single-mode fiber (SMF) parallel to the outer surface of the microbubble, in which the microbubble with a diameter of about 318 μm is constructed at the end of silica hollow tube. When external pressure is transmitted on the inner surface of the microbubble by the pressure leading-in tube, the FP cavity length changes with the diameter of microbubble. Experimental results show that such a sensor has a linear sensitivity of approximately 4.84 nm/MPa at room temperature over the pressure range of 1.1 MPa; the sensor has a very low temperature coefficient of approximately 2 pm/°C from room temperature to 600°C. The sensor has advantages of extremely low temperature coefficient, compact structure, and small size, which has potential applications for measuring pressure in high-temperature environment.

The optical fiber Fabry-Perot interferometer (FPI) has been widely investigated as a potential temperature sensor. To function as a temperature sensor, the cavity of the FPI is typically constructed from either silica fibers or polymers. The silica cavity FPIs can function at temperatures exceeding 1 000 °C. However, their temperature sensitivity is constrained by their relatively low thermal optical coefficients and thermal expansion of silica materials. Although the polymer cavity FPI exhibits high temperature sensitivity, its cavity is susceptible to deterioration in high-temperature environments. Here, to overcome this challenge and achieve high-sensitivity temperature sensing in a high-temperature environment, we propose a new type of temperature FPI sensor by inserting and sealing a section of Cr20Ni80 metal microwire inside a section of a silica hollow core fiber (HCF) spliced to a standard single-mode fiber (SMF). The FPIs exhibit a high degree of temperature sensitivity due to the high thermal expansion of the Cr20Ni80 metal microwire. Since the Cr20Ni80 metal has a high melting temperature of 1 400 °C, such FPIs can function in high-temperature environments. Moreover, the temperature sensitivity of this FPI can be modified without affecting its reflection spectrum by changing the length of the metallic microwire within the hollow core fiber. The experimental results indicate that the proposed FPIs exhibit temperature sensitivity of greater than −0.35 nm/°C within the temperature range of 50 °C to 440 °C. Our proposed metal microwire-based FPIs are economical, robust, simple to fabricate, and capable of functioning in high-temperature environments, rendering them appealing options for practical applications.

A non-sequential pulsed-mode deep reactive ion etching of silicon is reported that employs continuous etching and passivation based on SF6 and H2 gases. The passivation layer, as an important step for deep vertical etching of silicon, is feasible by hydrogen pulses in proper time-slots. By adjusting the etching parameters such as plasma power, H2 and SF6 flows and hydrogen pulse timing, the process can be controlled for minimum underetch and high etch-rate at the same time. High-aspect-ratio features can be realized with low-density plasma power and by controlling the reaction chemistry. The so-called reactive ion etching lag has been minimized by operating the reactor at higher pressures. X-ray photoelectron spectroscopy and scanning electron microscopy have been used to study the formation of the passivation layer and the passivation mechanism.