Micromachined Thermopile Based High Heat Flux Sensor

Transient heat flux sensors are widely used in unsteady thermal analyses. Commercial sensors currently available for high heat flux, however, have relatively low sensitivity. Micromachined thermopile based sensors with advantages of high sensitivity and small size, have been used for the measurement of heat flux produced by black body (usually in the level of W/m
²
), but not been tried to measure a heat flux on the order of MW/m
²
. In this paper, a high heat flux sensor based on structure-enhanced micromachined thermopile is careful designed and fabricated. Experiments using a powerful laser were conducted at ambient temperature to study the general performance, as well as the limit heat flux, of the sensor. The results show that the output signals have a linear characteristic with heat flux from 0.12 to 1.10 MW/m
²
. The sensitivity and response time of the sensor are $1.50\times 10^{-6}$ Vm
²
/W and 14 ms at 0.12 MW/m
²
, respectively. The sensor exhibits excellent repeatability in more than 200 laser pulses at 0.44 MW/m
²
. Limit check reveals that the sensor remains a good repeatability at 0.77 MW/m
²
and can survive at 1.10 MW/m
²
. The designed sensor shows a high performance and will provide a new effective path for measuring high heat flux fast and sensitively. [2019-0160].