Systems, devices, and methods for a two wire detection circuit powered system comprising: an electronic switch circuit configured to sense a pressure level above or below a predetermined value and indicate an open or closed switch condition, wherein the electronic switch circuit provides a contact resistance voltage of about 20 mV in the closed switch condition; and an energy harvester configured to convert 20 mV when the electronic switch circuit is in the closed switch condition to an operating voltage between 3.6 Volts and 5 Volts for the electronic switch circuit to operate without an additional power source.