Liquid level sensor

A method of maintaining a liquid level in a nebuliser cup during operation, the method comprising:

• providing a first element at or below a position corresponding to a filled liquid level in a nebuliser cup;
• providing a second element electrically isolated from the first element to contact a liquid at a position corresponding to a filled liquid level in the nebuliser cup;
• providing sufficient liquid to the nebuliser cup to reach said fill level thereby to complete an electrically coupled circuit between the first element, the liquid and the second element;
• and whereby a drop in the liquid level to below the fill level triggers a break in the circuit between the first element, the liquid and the second element;
• and
• whereby the break in the circuit triggers dispensation of further liquid in the nebuliser cup.