Demonstration of a joint power harvesting and communication technology for smartphone centric ubiquitous sensing applications

With the popularization of smartphones, various smartphone centric ubiquitous sensing applications have emerged, which use a smartphone in conjunction with external sensors for data acquisition, processing, display, communication, and storage. Because smartphones do not have a universal data interfaces, many ubiquitous sensing applications use the earphone and the microphone channels of the 3.5mm audio interface for data communications so that they can work with different types of smartphones. The earphone channels of the 3.5mm audio interface can only send AC signal out of a smartphone, and hence DC power needs to be harvested from the earphone channels. In this demonstration, a joint power harvesting and communication technology to harvest double or more power from both earphone channels (instead of one earphone channel) without affecting data communications is demonstrated with a prototype system, which can power external a microcontroller and sensors through the 3.5mm audio interface of a smartphone, display sensor measurement results on the smartphone, and control the outputs of the microcontroller from the smartphone.