Proprietary oximeter sensors and modules are expensive. To reduce cost, we are proposing to develop a simple audio pulse oximeter sensor (AudioOx) that that does not require a sensor module and interfaces via the audio jack of any standard cell phone. By utilizing the audio jack for transmission of data from the sensor to phone, we can ensure that cell phone types most common in various areas of the world are universally supported. Preliminary laboratory tests showed that oximetry data from the AudioOx has sufficient signal strength and resolution for extraction of heart rate and SpO2.