A single use, self-contained, self-powered disposable oximeter, in the form of a patch or a bandage strip, has mounted thereto a light emitter and a light sensor that together measure at least the SpO2 of the patient. Mounted to an electronics layer of the patch is an application specific integrated circuit (ASIC) that has electronics integrated thereto that controls the operation of the light emitter and light sensor, and the algorithm for calculating from the data collected by the sensor at least the SpO2 of the patient. Optionally, a display and an alarm may also be mounted or embedded onto the patch for respectively displaying at least the SpO2, and for informing the caregiver/patient that at least the SpO2 is not within an acceptable range, if such is the case. Also provided in the patch is a battery that powers the operation of the ASIC circuit and the emitter, as well as the display and alarm if such optional components are provided on the patch. An attachment mechanism is also provided on the patch. Such mechanism may be in the form of an adhesive layer that can removably attach the patch to the patient in either a transmissive mode or a reflective mode. The patch oximeter may also be equipped with a transceiver, and the appropriate electronics, for wirelessly transceiving information to/from a remote device or another wireless patch oximeter. In place of a self-contained power source, the power for operating a wireless patch oximeter may be retrieved from a remote power source, provided that the patch oximeter is within a given distance from such remote power source.