A negative pressure wound therapy system comprising: a wound dressing configured to be placed over a wound of a patient; a source of negative pressure disposed on or within the dressing, the source of negative pressure configured to provide negative pressure to the wound; and an electronic circuit disposed on or within the dressing, the electronic circuit comprising: a controller configured to operate the source of negative pressure; a power source configured to supply power to the electronic circuit; and an isolation circuit in electrical communication with the power source and the controller, the isolation circuit configured to operate in a first state in which the isolation circuit prevents application of power to the controller and in a second state in which the isolation circuit permits application of power to the controller, the isolation circuit comprising an activation switch configured to be activated and to cause the isolation circuit to operate in the second state, wherein the isolation circuit comprises a latching circuit, wherein the latching circuit is configured to cause the isolation circuit to remain in the second state in response to an initial activation of the activation switch. a wound dressing configured to be placed over a wound of a patient; a source of negative pressure disposed on or within the dressing, the source of negative pressure configured to provide negative pressure to the wound; and an electronic circuit disposed on or within the dressing, the electronic circuit comprising: a controller configured to operate the source of negative pressure; a power source configured to supply power to the electronic circuit; and an isolation circuit in electrical communication with the power source and the controller, the isolation circuit configured to operate in a first state in which the isolation circuit prevents application of power to the controller and in a second state in which the isolation circuit permits application of power to the controller, the isolation circuit comprising an activation switch configured to be activated and to cause the isolation circuit to operate in the second state, wherein the isolation circuit comprises a latching circuit, wherein the latching circuit is configured to cause the isolation circuit to remain in the second state in response to an initial activation of the activation switch. a controller configured to operate the source of negative pressure; a power source configured to supply power to the electronic circuit; and an isolation circuit in electrical communication with the power source and the controller, the isolation circuit configured to operate in a first state in which the isolation circuit prevents application of power to the controller and in a second state in which the isolation circuit permits application of power to the controller, the isolation circuit comprising an activation switch configured to be activated and to cause the isolation circuit to operate in the second state, wherein the isolation circuit comprises a latching circuit, wherein the latching circuit is configured to cause the isolation circuit to remain in the second state in response to an initial activation of the activation switch. <EOS>