Design, Simulation, and Fabrication of a Copper–Chrome-Based Glass Heater Integrated into a PMMA Microfluidic System

In this paper, the development of a copper–chrome-based glass microheater and its integration into a Polymethylmethacrylate (PMMA) microfluidic system are presented. The process highlights the importance of an appropriate characterization, taking advantage of computer-simulated physical methods in the heat transfer process. The presented system architecture allows the integration for the development of a thermal flow sensor, in which the fluid flows through a 1 mm width × 1 mm length microchannel across a 5 mm width × 13 mm length heating surface. Using an electrothermal analysis, based on a simulation and design process, the surface heating behavior curve was analyzed to choose a heating reference point, primarily used to control the temperature point within the fluidic microsystem. The heater was characterized using the theory of electrical instrumentation, with a 7.22% error for the heating characterization and a 5.42% error for the power consumption, measured at 0.69 W at a temperature of 70 °C. Further tests, at a temperature of 115 °C, were used to observe the effects of the heat transfer through convection on the fluid and the heater surface for different flow rates, which can be used for the development of thermal flowmeters using the configuration presented in this work.

Adaptive Measurement Control of a Thermal Flow Sensor

In the present work, an adaptive gain switching control strategy and a digital temperature compensation technique are integrated with a hot-thermistor anemometer to achieve sensor speed and accuracy improvement. The limitation of the Wheatstone bridge technique for temperature thermistors is compensated to achieve accuracy improvement. The feedback control gains are adapted to the particular range of airflow rates to achieve faster response. Simulation results have confirmed the response speed and accuracy improvement with the proposed digital sensor system. The proposed design has been implemented, and experiments have been conducted. Compared to an original thermal flow sensor with analog circuit, the measurement speed is significantly improved at low airflow rates with adaptive feedback control gains implemented in the prototype digital sensor system. The developed digital sensor system possesses desirable features such as a direct interface to the computer through a serial port, easy change of operational parameters and sensor configurations, and energy conservation, as well as simpler control design with the use of Pulse Width Modulation (PWM) to control the probe heater power.

Adaptive Measurement Control of a Thermal Flow Sensor

In the present work, an adaptive gain switching control strategy and a digital temperature compensation technique are integrated with a hot-thermistor anemometer to achieve sensor speed and accuracy improvement. The limitation of the Wheatstone bridge technique for temperature thermistors is compensated to achieve accuracy improvement. The feedback control gains are adapted to the particular range of airflow rates to achieve faster response. Simulation results have confirmed the response speed and accuracy improvement with the proposed digital sensor system. The proposed design has been implemented, and experiments have been conducted. Compared to an original thermal flow sensor with analog circuit, the measurement speed is significantly improved at low airflow rates with adaptive feedback control gains implemented in the prototype digital sensor system. The developed digital sensor system possesses desirable features such as a direct interface to the computer through a serial port, easy change of operational parameters and sensor configurations, and energy conservation, as well as simpler control design with the use of Pulse Width Modulation (PWM) to control the probe heater power.

Design of high-resolution flow sensor used in cold gas micro propulsion system

Cold Gas Micro Propulsion (CGMP) is a reliable technology for spacecraft attitude and orbit control used in drag-free control system to compensate the environmental disturbance from the aerospace. The CGMP requiring a very fine control resolution and low noise is desired to be used on TAIJI mission for gravitational wave detection which is supported by Chinese Academy of Science (CAS). One of CGMP’s key technologies is high-resolution Gas Mass Flow Sensor (GMFS). In this paper, calorimetric thermal flow sensor characterized with miniaturization, high sensitivity and low noise is studied by simulation method and manufacturing process. By simulating the influence of heating power, electrode distance, temperature, etc. on sensor response, the methods on optimizing sensitivity and accuracy have been proposed. The sensitivity is about 2.53 mV/(m/s)/mW. An amplifier circuit with ultra-low noise of 7.29 nV/[Formula: see text]Hz for reading out has been designed, which is essential for high resolution. The sensor was fabricated and preliminary tests have been conducted. The sensitivity of the sensor is about 100 mV/(m/s).