The humble smartphone stylus may soon be gaining new features, thanks to a seemingly simple piece of technology. Developed by Korea Advanced Institute of Science and Technology (KAIST) PhD student Sungjae Hwang, the MagPen is essentially just a plastic tube covered in conductive tape, with conductive rubber tips at either end and a coin-shaped magnet inserted half-way down its length. Via a custom app, however, magnetometers already present in the phone are able to determine where that magnet is in relation to the screen, and respond with a variety of drawing and writing functions.
Any existing smartphone or tablet should be compatible, as long as it already contains the magnetometers and associated electronics that most such devices use as a compass.
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By sensing the proximity of the pen's magnet, the magnetometer-enabled app is able to tell not only how close the pen is to the screen, but also where its tip is on the screen, the angle at which it’s being held, and even the amount of finger pressure that’s being exerted on the glass. Different “ink” colors can even be chosen by going off the screen, and dragging the pen’s tip across the phone’s frame.
Because the app can differentiate between the magnetic qualities of multiple MagPens, users could alternately change colors by using different pens.
The app can also tell when the magnet (and thus the pen) has been spun around, by detecting which pole is closest to the phone. This allows for extra functionality, letting one end of the pen be used for writing and the other for erasing, as an example. In another mode, turning the pen around allows users to change between different line widths – this can also be done simply by pressing harder when drawing. In fact, the pen can be spun in three different fashions, each of which allows the user to access different functions.
Hwang was advised by KAIST’s Prof. Kwang-yun Wohn, and worked in collaboration with master’s student Myung-Wook Ahn and Sungkyunkwan University’s Prof. Andrea Bianchi. He has filed patents for the technology, which is demonstrated in the video below.