Switch circuitry for a fluid monitoring device

A switch circuitry for controlling power supplied to a fluid monitoring unit, the switch circuitry comprising:

• a sensor configured to detect fluid derived from the skin of a user and to generate a detection signal in accordance with detection of fluid;
• and
• a controller configured to receive the detection signal, to generate a wake-up signal in accordance with the detection signal, and to supply the wake-up signal to a switch controlling the power supply to the fluid monitoring unit so as to activate the switch and wake the fluid monitoring unit,
• wherein
• the sensor is configured to:
• detect a first amount of fluid at a first time point;
• detect a second amount of the fluid at a second time point occurring after the first time point;
• calculate a difference between the first amount of fluid and the second amount of fluid;
• and
• generate the detection signal when the difference between the first amount of fluid and the second amount of fluid exceeds a predetermined threshold.