Electrode connection monitoring

Apparatus comprising:

• an electrode assembly comprising three electrodes:
• a first, a second and a reference electrode, mounted on a common substrate in a fixed spatial relationship one to another wherein said reference electrode lies approximately equidistant from said first and second electrodes, said electrode assembly adapted for being applied to the skin of an individual,
• inputs for receiving signals from said electrodes,
• wherein the apparatus is operative to measure EMG signals from said electrode(s) when the electrodes are applied to the skin and provide an electrical stimulation feedback signal to the reference electrode such that current passes from the reference electrode to each of the first and second electrodes upon the detection of EMG signals indicative of a muscular activity relating to bruxism of the individual,
• said apparatus further comprising:
• a source of a monitoring signal having a frequency and outputs for use in applying said monitoring signal alternately to said first and second electrodes,
• wherein the apparatus is operative to determine the amplitude of the monitoring signal at said frequency at the input of said reference electrode,
• wherein the amplitude of the monitoring signal at said frequency at said reference electrode is measured to determine the quality of the connection via the skin between the first electrode and the reference electrode and the quality of the connection via the skin between the second electrode and the reference electrode, and wherein the intensity of the electrical stimulation feedback signal is modulated if the quality of the electrical connection between the electrodes is changed.