Abstract
The present invention discloses a kind of thermal pulsed micro flow sensor, comprising a flow channel used for test fluid pass through; a heater, located upstream of the flow channel and heating the fluid passing through the channel; and at least three thermal sensors located downstream from the heater in the flow channel, used for sensing thermal pulses carried by the fluid flowing the thermal sensors. The distance relations among at least three heat sensors are the distance L1 between the first thermal sensor (S0) at the relatively most upstream of flow channel and the third thermal sensor (S10) at the most downstream is: dF=(A*L13)*{1/T1}-1/(T1+dT)}; wherein dF is the resolution required by the system in units of micro seconds; A is the cross-sectional area of the flow channel; T1 can be expressed as T1= (A*L1)/F1, wherein F1 is the maximum flow rate allowed in the testing parameter in units of sccm; and dT is thermal pulse signal distortion resolution in units of micro seconds; and the distance L2 between the first thermal sensor (S0) at the relatively most upstream of flow channel and the second thermal sensor (Sz) at the relatively next downstreamd is dF=(A*L2)*{1/T2}-1/(T2+dT)}, wherein, dF, A, dT have the same definition above, T2 is expressed by T2=(A*L2)/F2, wherein F2={(A*L1)/R}+<alpha>1; R is the response time required by the flow meter, <alpha> is a predetermined adjustment value to overlap the sensing ranges of S1 and S2. The present invention also discloses a flow rate measurement method using said thermal pulsed flow meter.