Broad problem statement:

Design, implement and characterise a smart-phone based instrument to measure ambient temperature.

Background and more details:

Smart phones are packed with sensors that make it possible to measure a number of other variables that don't necessarily have anything to do with the original purpose of a phone.

Your task is to make use of the onboard sensors available on your smart phone to design an instrument to measure the ambient temperature in an environment (e.g. a room).

Some smart phones have sensors to monitor the temperature of their battery and is used by some apps to monitor ambient temperature. You are not allowed to use this sensor in your design, although this sensor can be used as part of your calibration procedure.

Similarly using existing thermal sensors (e.g. thermistors, RTDs or thermocouples etc.) to measure temperature and importing such a measurement via an electronic interface is also not allowed, since the mobile phone sensors then become redundant in your design. The principal here is that your mobile phone sensors should be necessary for your design to be able to measure temperature.