Fabrication and evaluation of a graphene oxide-based cantilever-type flow-meter for subsonic gas flow rate measurement

Abstract

In this paper, a cantilever-type flow meter was fabricated to measure the rate of air flow in turbulent subsonic regimes such as purged gases. In the fabrication process, a piezoresistive material was coated on an interdigitated electric board as a substrate. The piezoresistive layer was a blend of latex as the polymeric matrix and graphene oxide as the sensing nanomaterial agent, which was reduced by solvothermal reduction method. The piezoresistive blend was dip-coated on a substrate with dotted pattern and was then reduced at 240 °C for 1 h in every coating step. When an air flow passed over the surface of the cantilever beam, the beam was bent in the downward direction, resulting in small variations in the resistance of the piezoresistive layer and a change in the bending angle of the cantilever which were measured simultaneously. The air flow rate was acquired via calibrating electrical resistance changes by Arduino and Wheatstone bridge circuit. The blending angle of the substrate caused by the interaction between the airflow and the cantilever and recorded by the camera and image processing was ultimately compared with the simulation results. The flow meter accuracy as a percentage of full scale (% FS) was calculated to be ±5.8%, and mean deviation was equal to 2.1 (% FS) with the appropriate response time of 0.70 s at the air flow range of 100−240 m s−1. Highlights • A cantilever-type flow meter was fabricated to measure the high-speed air flow rate. • The sensitive piezoresistive material was composed of GO and latex. • The dip-coating method was used to deposit the piezoresistive layer on the fiberglass substrate. • The impact of effective parameters on the performance of the flow meter was investigated. • A simulation study was performed and the results were compared with the experimental data.

Wall Shear Stress Sensors Based on Carbon Nanotube Pillars

“…2,13 They can be designed to resolve low-speed flows and can directly measure wall shear stress. 2,3,14,15 Drag-based sensors have also been designed to imitate sensory structures on bats, seals, and fish, taking the form of slender hairs extending from a surface. 16−19 However, drag-based flow sensors are intrusive measurement instruments in that the sensor is placed in the flow to be measured, which could disturb flow development.…”

“…Fluid flow sensors have been developed that operate by registering a signal based on thermal or deformation changes, − , with each category of flow sensor having advantages. By avoiding fluid heating, sensors that operate by deforming due to drag forces often boast low power requirements and better compatibility with explosive gases and sensitive biological fluids. , They can be designed to resolve low-speed flows and can directly measure wall shear stress. ,,, Drag-based sensors have also been designed to imitate sensory structures on bats, seals, and fish, taking the form of slender hairs extending from a surface. − …”

A suspended polymeric microfluidic sensor for liquid flow rate measurement in microchannels

“…Image analysis was employed to determine the cantilever's deflection. Hamdollahi et al 15 also studied a cantilever-based air flowmeter that calculates gas flow rate through image processing.…”

An internal miniature diversion channel-integrated piezoelectric airflow sensor

“…For instance, thermal airflow sensors and ultrasonic wind sensors are highly sensitive to the environmental temperature and humidity [1], and piezoresistive airflow sensors are easily disturbed by a magnetic field or an electric field [25]. In addition, since that piezoresistive airflow sensors commonly operate by measuring resistance changes of a cantilever, measurement of bending and deformation of the cantilever is indirect [23,25,31]. However, via the piezoelectric principle, measurement of bending and deformation of a cantilever can be obtained in a more direct and accurate way [32] because mechanical movements can be directly converted into electric signals in piezoelectric sensing elements.…”