An actively-powered temperature data logger patch with wireless data communication, comprising: a first substrate layer comprising a first end and an opposite second end; a sealed, flexible battery comprising a printed electrochemical cell with an anode and a cathode, at least one of said anode and cathode being formed of a cured or dried ink, and first and second battery electrode contacts (33A, 33B) that are each electrically coupled to one of the anode and cathode; a flexible circuit comprising a microprocessor, a temperature sensor configured to sense a temperature of a target subject, a wireless communication transmitter and an antenna, the flexible circuit further comprising first and second battery contact pads (35A, 35B) that are each electrically coupled to one of the first and second battery electrode contacts (33A, 33B) to thereby electrically power the microprocessor, wireless communication transmitter, and temperature sensor, a second substrate layer comprising an adhesive configured to be removably applied to a surface of the target subject, wherein the flexible battery and flexible circuit together define an electronics inlay that is arranged in a covering, stacked arrangement between the first and second substrate layers, and wherein all of the first substrate layer, electronics inlay, and second substrate layer are flexible and configured to conform to a curved surface of the target subject, and wherein all of the microprocessor, temperature sensor, and wireless communication transmitter actively receive electrical power from the flexible battery, characterized in that the temperature sensor is located at the first end of the first substrate layer, and the antenna is located at the second end of the first substrate layer, wherein the first substrate layer comprises a first edge extending along the first end, the temperature sensor being positioned along the first edge, and wherein the first substrate layer comprises a second edge extending along the second end, the antenna being positioned along the second edge, wherein the flexible circuit has a generally "L"-shaped geometry that extends along a longitudinal axis of the patch, and wherein the temperature sensor is located at a left-hand side of the patch, while the antenna is located on an opposite right-hand side of the patch, and wherein the flexible battery and an integrated circuit on the flexible circuit and in communication with the temperature sensor are located in between. a first substrate layer comprising a first end and an opposite second end; a sealed, flexible battery comprising a printed electrochemical cell with an anode and a cathode, at least one of said anode and cathode being formed of a cured or dried ink, and first and second battery electrode contacts (33A, 33B) that are each electrically coupled to one of the anode and cathode; a flexible circuit comprising a microprocessor, a temperature sensor configured to sense a temperature of a target subject, a wireless communication transmitter and an antenna, the flexible circuit further comprising first and second battery contact pads (35A, 35B) that are each electrically coupled to one of the first and second battery electrode contacts (33A, 33B) to thereby electrically power the microprocessor, wireless communication transmitter, and temperature sensor, a second substrate layer comprising an adhesive configured to be removably applied to a surface of the target subject, wherein the flexible battery and flexible circuit together define an electronics inlay that is arranged in a covering, stacked arrangement between the first and second substrate layers, and wherein all of the first substrate layer, electronics inlay, and second substrate layer are flexible and configured to conform to a curved surface of the target subject, and wherein all of the microprocessor, temperature sensor, and wireless communication transmitter actively receive electrical power from the flexible battery, characterized in that the temperature sensor is located at the first end of the first substrate layer, and the antenna is located at the second end of the first substrate layer, wherein the first substrate layer comprises a first edge extending along the first end, the temperature sensor being positioned along the first edge, and wherein the first substrate layer comprises a second edge extending along the second end, the antenna being positioned along the second edge, wherein the flexible circuit has a generally "L"-shaped geometry that extends along a longitudinal axis of the patch, and wherein the temperature sensor is located at a left-hand side of the patch, while the antenna is located on an opposite right-hand side of the patch, and wherein the flexible battery and an integrated circuit on the flexible circuit and in communication with the temperature sensor are located in between.