Design And Fabrication Of Sound Particle Velocity Sensor For Fabrication Of Micro-Flown

Normally, micro-flown consist of two thin and suspended metal wires made of platinum with a close distance of about ۱ mm in length and about ۳ to ۶ micro-meters in width, which are heated to a temperature of ۴۵۰ °C and simultaneously act as a sensing element and heater. When there is fluid flow, the temperature distribution around these resistors changes asymmetrically and a temperature difference occurs between the two wires. The difference in their resistance quantifies the speed of the particles and can be measured. Therefore, this thermal acoustic sensor measures the speed of particles instead of sound pressure. In this article, an acoustic sensor for measuring the speed of particles or the direction of sound is investigated. To implement this goal, after designing the manufacturing process, the final structure was made on the silicon substrate using the micromachining process, and then the reading circuit was designed according to the built sensor in order to fully identify the signal and send it to the system for digital processing. To reduce the coupling between wires and body the wires in this structure have been floated from the silicon surface using a wet etching process, which has significant effects. This sensor has the ability to measure the sound in the range of ۱۰۰ to ۲۰۰۰ Hz and the sensitivity of the sensor is ۳ microvolts, which can be used to measure the direction of sound waves in most processes.

کلیدواژه ها:

Micro-flown ، Acoustic sensor ، Micromachining ، MEMS devices ، Wet etching