A sensor module (46, 110, 112) for sensing characteristics of a fluid flowing through a fluid conduit, comprising: a sample probe adapted, in use, to be at least partially positioned within the fluid conduit with an upstream facing side and a downstream facing side, the sample probe comprising: at least one hollow sample arm (140, 142) having a radially outer end and an inner end and that, in use, extends radially inwardly from a sidewall portion of the fluid conduit to a center portion of the fluid conduit, the at least one hollow sample arm (140, 142) including a fluid flow channel formed therein and comprising a plurality of upstream facing inlet apertures communicating with the fluid flow channel; and a sensor well located at the radially outer end of the at least one sample arm (140, 142), the sensor well having an interior volume in fluid communication with the fluid flow channel, the sensor well comprising a closed upstream facing front portion and a downstream facing back portion having a discharge aperture formed therein; and a sensor positioned at least partially within the interior volume of the sensor well: characterized in that: the front portion of the sensor well has a blunt, rounded front surface; and in that: a volume per unit length of the fluid flow channel is smaller than a volume per unit length of the interior volume of the sensor well, such that the at least one hollow sample arm (140, 142) has a width less than a width of the sensor well. a sample probe adapted, in use, to be at least partially positioned within the fluid conduit with an upstream facing side and a downstream facing side, the sample probe comprising: at least one hollow sample arm (140, 142) having a radially outer end and an inner end and that, in use, extends radially inwardly from a sidewall portion of the fluid conduit to a center portion of the fluid conduit, the at least one hollow sample arm (140, 142) including a fluid flow channel formed therein and comprising a plurality of upstream facing inlet apertures communicating with the fluid flow channel; and a sensor well located at the radially outer end of the at least one sample arm (140, 142), the sensor well having an interior volume in fluid communication with the fluid flow channel, the sensor well comprising a closed upstream facing front portion and a downstream facing back portion having a discharge aperture formed therein; and at least one hollow sample arm (140, 142) having a radially outer end and an inner end and that, in use, extends radially inwardly from a sidewall portion of the fluid conduit to a center portion of the fluid conduit, the at least one hollow sample arm (140, 142) including a fluid flow channel formed therein and comprising a plurality of upstream facing inlet apertures communicating with the fluid flow channel; and a sensor well located at the radially outer end of the at least one sample arm (140, 142), the sensor well having an interior volume in fluid communication with the fluid flow channel, the sensor well comprising a closed upstream facing front portion and a downstream facing back portion having a discharge aperture formed therein; and a sensor positioned at least partially within the interior volume of the sensor well: characterized in that: the front portion of the sensor well has a blunt, rounded front surface; and in that: a volume per unit length of the fluid flow channel is smaller than a volume per unit length of the interior volume of the sensor well, such that the at least one hollow sample arm (140, 142) has a width less than a width of the sensor well.