Hijack uses the iPhone headphone jack to create a cheap Sensor

It is not that easy to produce accessories that match the base connector of iOS devices: you need some parts provided by Apple, and you need to spend a lot of money to buy Apple's "made"
IPhone license. However, you can use the headphone jack as the entry point for two-way data communication with the iPhone, and use the power of the iPhone to drive small circuit boards. From secret receipt
A group of teachers and students from the department of electronic engineering and computer science at anuniversity invented a device called hijack to enable people without money to play with sensing devices.

Project hijack is a hardware and software platform for communication between small and low-power peripheral devices and iOS devices.
The system uses a 22 Khz audio signal and converts it into a 47% MW Power (conversion efficiency of), which can drive
The MSP430 microcontroller and other electronic components allow communication between hijack and iOS applications. When there are more than 10 thousand hijacks in batches, the cost of producing a hijack is only USD 2.34.

And Related to hijackSource codeCan be found on Google Code. If you are interested and understand welding technology, you may wish to do it yourself. Currently, the platform software only supports iOS, and the hardware supports almost all mobile devices with headphones/microphone jacks. The project team also plans to develop API services so that hijack can run on Android and Windows Phone 7.

Here are some demos. If you are going through the wall, you can also watch this video.

Via arstechnica