A flowmeter with piezoresistive metal layer deposited with focused-ion-beam system

In this paper, we fabricated and evaluated a flowmeter with a sub-micron sized piezoresistive layer for the measurement in the small area. For the small area detection, the sensing material should be reduced as well as sensor body. We use the FIB system to reduce the size of the sensing material and obtain the sub-micron sized line width. The device is fabricated with the standardMEMS process, and the platinum layer is selected as the piezoresistive material considering the electrical conductivity. The 0∼4m/s air flows are applied to the flowmeter and the experimental results shows the negative sensitivity output with -3.22E^-5/ms^-1. This negative value is due to the additional materials like carbon and gallium. The various experiments including stability and repeatability are performed, and the repeated operation shows stable output signals with less than 9.6% variation. Through those experiment results, the FIB assisted platinum layer is suitable for the piezoresistive detection and a flowmeter can be applied to measurement of flow rate in the small area.