A disc pump system comprising: a pump body having a substantially cylindrical sidewall closed at both ends by a first end wall and a driven end wall having a central portion and a peripheral portion extending radially outwardly from the central portion; an internal sidewall disposed within cylindrical sidewall to define the diameter of a cavity formed by the internal sidewall, the first end wall, and the driven end wall the diameter of the internal sidewall being changeable in response to a change in temperature; an actuator operatively associated with the central portion of the driven end wall to cause oscillatory motion of the driven end wall at a frequency ( f), thereby generating displacement oscillations of the driven end wall in a direction substantially perpendicular thereto resulting in a change in temperature, the diameter of the internal sidewall being responsive to the change in temperature; an isolator operatively associated with the peripheral portion of the driven end wall to reduce dampening of the displacement oscillations; a first aperture (27, 31) disposed at any location in either one of the end walls other than at the annular node and extending through the pump body; a second aperture (27, 31) disposed at any location in the pump body other than the location of the first aperture (27, 31) and extending through the pump body; a valve (29, 32) disposed in at least one of the first aperture (27, 31) and the second aperture (27, 31); whereby the displacement oscillations generate corresponding pressure oscillations of the fluid within the cavity of the pump body causing fluid flow through the first aperture (27, 31) and second aperture (27, 31) when in use. a pump body having a substantially cylindrical sidewall closed at both ends by a first end wall and a driven end wall having a central portion and a peripheral portion extending radially outwardly from the central portion; an internal sidewall disposed within cylindrical sidewall to define the diameter of a cavity formed by the internal sidewall, the first end wall, and the driven end wall the diameter of the internal sidewall being changeable in response to a change in temperature; an actuator operatively associated with the central portion of the driven end wall to cause oscillatory motion of the driven end wall at a frequency ( f), thereby generating displacement oscillations of the driven end wall in a direction substantially perpendicular thereto resulting in a change in temperature, the diameter of the internal sidewall being responsive to the change in temperature; an isolator operatively associated with the peripheral portion of the driven end wall to reduce dampening of the displacement oscillations; a first aperture (27, 31) disposed at any location in either one of the end walls other than at the annular node and extending through the pump body; a second aperture (27, 31) disposed at any location in the pump body other than the location of the first aperture (27, 31) and extending through the pump body; a valve (29, 32) disposed in at least one of the first aperture (27, 31) and the second aperture (27, 31); whereby the displacement oscillations generate corresponding pressure oscillations of the fluid within the cavity of the pump body causing fluid flow through the first aperture (27, 31) and second aperture (27, 31) when in use.