Negative pressure wound therapy apparatus

A pump assembly apparatus for applying negative pressure to a wound, comprising:

• a magnetic circuit comprising:
• an upper pole;
• a lower pole spaced apart from the upper pole;
• and
• a magnet positioned between at least a portion of the upper pole and the lower pole;
• an electrically conductive voice coil, at least a portion of which is disposed between the upper pole and the lower pole, the electrically conductive voice coil being configured to move within at least a portion of the magnetic circuit;
• a wound dressing configured to sealingly surround a wound;
• a diaphragm;
• and
• one or more valves configured to control a flow of fluid through the pump assembly;
• wherein:
• the voice coil is configured to move the diaphragm to pump a fluid through the pump assembly in response to a drive signal applied to the voice coil.