A microsensor housing having a structure with at least one inlet at one end and a thermal property sensor at the other end. Situated between the inlet and the sensor is a convection shield. Sampled fluid is taken in the inlet from a channel carrying the fluid to be sampled. The convection flow lines of the fluid are barred by the convection shield. The fluid is diffused into a cavity between the shield and sensor. The sensor detects a thermal property of the diffused fluid. One preferred shield has holes about its perimeter with a solid center part of the shield covering at a distance the sensor. The channel carrying the fluid may have screens to reduce turbulence noise and to aid in fluid transport to and from the sensor housing.