A system, comprising: a housing comprising a base portion and a cap portion attached to the base portion; a dipstick portion attached to the base portion of the housing and having a distal tip spaced from the housing, wherein the dipstick portion includes an interior chamber and a plurality of vent apertures, the vent apertures disposed along the length of the dipstick portion, and wherein the dipstick portion also defines at least one fluid entry aperture that is located proximate to the distal tip, each of the at least one fluid entry aperture being configured to provide an access opening that allows fluid into the interior chamber of the dipstick portion, the housing and dipstick portion configured for removable attachment to a reservoir such that when the housing is attached to the reservoir the dipstick portion contacts the fluid in the reservoir; a sensor disposed in the interior chamber of the dipstick portion and configured to contact a fluid and measure a characteristic of the fluid; one or more processors operably coupled to the sensor, the one or more processors configured to generate one or more data signals representative of the characteristic of the fluid that is measured by the sensor; a transmitter operably coupled to the one or more processors, the transmitter configured to wirelessly communicate the one or more data signals to a remote reader wherein the one or more processors and the transmitter are disposed within the housing; and a capacitance control plate configured to reduce the capacitance of the one or more processors relative to the sensor capacitance of the sensor or to isolate the sensor capacitance of the sensor from the one or more processors the capacitance control plate disposed between at least a part of the housing and the dipstick portion. a housing comprising a base portion and a cap portion attached to the base portion; a dipstick portion attached to the base portion of the housing and having a distal tip spaced from the housing, wherein the dipstick portion includes an interior chamber and a plurality of vent apertures, the vent apertures disposed along the length of the dipstick portion, and wherein the dipstick portion also defines at least one fluid entry aperture that is located proximate to the distal tip, each of the at least one fluid entry aperture being configured to provide an access opening that allows fluid into the interior chamber of the dipstick portion, the housing and dipstick portion configured for removable attachment to a reservoir such that when the housing is attached to the reservoir the dipstick portion contacts the fluid in the reservoir; a sensor disposed in the interior chamber of the dipstick portion and configured to contact a fluid and measure a characteristic of the fluid; one or more processors operably coupled to the sensor, the one or more processors configured to generate one or more data signals representative of the characteristic of the fluid that is measured by the sensor; a transmitter operably coupled to the one or more processors, the transmitter configured to wirelessly communicate the one or more data signals to a remote reader wherein the one or more processors and the transmitter are disposed within the housing; and a capacitance control plate configured to reduce the capacitance of the one or more processors relative to the sensor capacitance of the sensor or to isolate the sensor capacitance of the sensor from the one or more processors the capacitance control plate disposed between at least a part of the housing and the dipstick portion.