Minimum Detectable Air Velocity by Thermal Flow Sensors

Issa, Safir; Lang, Walter

doi:10.3390/s130810944

Cited by 16 publications

(6 citation statements)

References 17 publications

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“…With this approach, it is possible to precisely control the injected volume and to alternate suction and injection phases. Another method allowing generation of very small flow rate and precise monitoring of the injected volumes is based on using a gravity-driven water flow to displace the desired airflow [ 26 ]. This second approach produces much smoother airflow than a syringe pump, but the flow is less controllable.…”

Section: Resultsmentioning

confidence: 99%

Precise Measurement of Gas Volumes by Means of Low-Offset MEMS Flow Sensors with μL/min Resolution

Piotto

Cesta

Bruschi

2017

Sensors

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Experiments devoted to evaluate the performance of a MEMS thermal flow sensor in measuring gas volumes are described. The sensor is a single-chip platform, including several sensing structures and a low-offset, low-noise readout interface. A recently proposed offset compensation approach is implemented obtaining low temperature drift and excellent long time stability. The sensor is fabricated by applying a simple micromachining procedure to a chip produced using the BCD6s process of STMicroelectronics. Application of a gas conveyor allowed inclusion of the sensing structure into a channel of sub-millimeter cross-section. The results of measurements performed by making controlled air volumes pass through the sensor channel in both directions at rates from 0.1 to 5 mL/min are described.

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Section: Resultsmentioning

confidence: 99%

Precise Measurement of Gas Volumes by Means of Low-Offset MEMS Flow Sensors with μL/min Resolution

Piotto

Cesta

Bruschi

2017

Sensors

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“…2c, demonstrating that the differential output of P1 can be monitored as a linear function in the flow velocity range of 0-1.25 m•s −1 with a sensitivity of 1.817 V•m −1 s. The minimum detectable velocity was calculated to be 0.11 mm•s −1 based on the noise level of the P1 (9.8 × 10 −5 V) (Supplementary Fig. 6A) and 2σ criterion 34 . However, the differential output of P2 (D = 320 μm) is higher than that of P1 (D = 120 μm) when the flow velocity is less than 0.2 m•s −1 (see the inset in Fig.…”

Section: Sensing Characteristics Of the Fcf Sensormentioning

confidence: 88%

Flexible calorimetric flow sensor with unprecedented sensitivity and directional resolution for multiple flight parameter detection

Gong,

Di,

Jiang

et al. 2024

Nat Commun

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The accurate perception of multiple flight parameters, such as the angle of attack, angle of sideslip, and airflow velocity, is essential for the flight control of micro air vehicles, which conventionally rely on arrays of pressure or airflow velocity sensors. Here, we present the estimation of multiple flight parameters using a single flexible calorimetric flow sensor featuring a sophisticated structural design with a suspended array of highly sensitive vanadium oxide thermistors. The proposed sensor achieves an unprecedented velocity resolution of 0.11 mm·s−1 and angular resolution of 0.1°. By attaching the sensor to a wing model, the angles of attack and slip were estimated simultaneously. The triaxial flight velocities and wing vibrations can also be estimated by sensing the relative airflow velocity due to its high sensitivity and fast response. Overall, the proposed sensor has many promising applications in weak airflow sensing and flight control of micro air vehicles.

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“…The standard deviation of the noise voltage is estimated at nearly 0.002 mV. Considering the sensitivity, the minimum detectable flow rate[17] of the type A and type B sensors are 0.53 and 0.26 sccm, respectively.Micromachines 2020,11, 205 9 Output noise of the type B sensor plotted as a function of time in the zero-flow case.…”

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confidence: 95%

A Front-Side Microfabricated Thermoresistive Gas Flow Sensor for High-Performance, Low-Cost and High-Yield Volume Production

Xue

Wang

2020

Micromachines

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In this paper, we present a novel thermoresistive gas flow sensor with a high-yield and low-cost volume production by using front-side microfabricated technology. To best improve the thermal resistance, a micro-air-trench between the heater and the thermistors was opened to minimize the heat loss from the heater to the silicon substrate. Two types of gas flow sensors were designed with the optimal thermal-insulation configuration and fabricated by a single-wafer-based single-side process in (111) wafers, where the type A sensor has two thermistors while the type B sensor has four. Chip dimensions of both sensors are as small as 0.7 mm × 0.7 mm and the sensors achieve a short response time of 1.5 ms. Furthermore, without using any amplification, the normalized sensitivity of type A and type B sensors is 1.9 mV/(SLM)/mW and 3.9 mV/(SLM)/mW for nitrogen gas flow and the minimum detectable flow rate is estimated at about 0.53 and 0.26 standard cubic centimeter per minute (sccm), respectively.Micromachines 2020, 11, 205 2 of 10 insulation membrane is formed by potassium hydroxide (KOH) anisotropic etching from the wafer backside. The anisotropic etching-induced inclined sidewalls cause the chip size to be quite large and the back-sided KOH etching is time-consuming, which yield a higher batch-fabrication cost [10]. Thus, developing a new strategy to minimize the chip size for realizing batch-fabrication with a lower cost is an important issue. Recently, a commercial 0.35 µm 2P4M microelectromechanical systems (MEMS) process was used in [11] to fabricate a sensor from the front-side of a (100) wafer. The approach decreased the chip-size and fabrication cost. However, the insulation membrane was released through XeF 2 isotropic etching, Thus, a depth-limited insulation cavity was formed, which would increase the heat loss, lower the thermal resistance and cause a relatively lower sensitivity of the sensor. Here, this paper expands on preliminary research presented in [12] and explores a tiny-sized ultrasensitive thermoresistive gas flow sensor that is single-side processed in an ordinary single-polished (111) silicon wafer. By changing the number of thermoresistive sensors, we developed two types of differential thermoresistive gas flow sensors, a half-bridge type and a full-bridge type.

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Minimum Detectable Air Velocity by Thermal Flow Sensors

Cited by 16 publications

References 17 publications

Precise Measurement of Gas Volumes by Means of Low-Offset MEMS Flow Sensors with μL/min Resolution

Precise Measurement of Gas Volumes by Means of Low-Offset MEMS Flow Sensors with μL/min Resolution

Flexible calorimetric flow sensor with unprecedented sensitivity and directional resolution for multiple flight parameter detection

A Front-Side Microfabricated Thermoresistive Gas Flow Sensor for High-Performance, Low-Cost and High-Yield Volume Production

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