A position sensing apparatus includes a position sensor, a voltage/current detector, and an alarm. The position sensor is coupled to the body part and includes a capsule, and first and second electrodes. The capsule has an interior volume configured to contain a liquid with a first density, and a contact member having a second density different from the first density. The first and second electrodes are fixed to the capsule to define a sensor meridian that is coupled to a tilt angle of the body part, with each electrode having a distal portion in the interior volume of the capsule, and the distal portions being configured to form a circuit with the liquid or the contact member. The voltage/current detector is configured to detect a change in a state of the circuit, and the alarm is configured to respond to the voltage/current detector.
